Prepared in cooperation with the 

Statewide Water-Quality 

Network for Massachusetts

Water-Resources Investigations Report 01-4081

U.S. Department of the Interior 

U.S. Geological Survey

MASSACHUSETTS DEPARTMENT OF ENVIRONMENTAL PROTECTION

DIVISION OF WATERSHED MANAGEMENT
Cover photo is the Konkapot River at Ashley Falls,

Sheffield, Massachusetts. Photo by Gardner Bent.
U.S. Department of the Interior

U.S. Geological Survey

Statewide Water-Quality 

Network for Massachusetts

By LESLIE A. DESIMONE, PETER A. STEEVES, and 

MARC J. ZIMMERMAN

Water-Resources Investigations Report 01-4081

Prepared in cooperation with the

MASSACHUSETTS DEPARTMENT OF ENVIRONMENTAL 

PROTECTION, DIVISION OF WATERSHED MANAGEMENT

Northborough, Massachusetts

2001
U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

The use of trade or product names in this report is for identification 

purposes only and does not constitute endorsement by the 

U.S. Government.

For additional information write to: Copies of this report can be purchased 

Chief, Massachusetts-Rhode Island District U.S. Geological Survey

U.S. Geological Survey Branch of Information Services

Water Resources Division Box 25286

10 Bearfoot Road Denver, CO 80225-0286

Northborough, MA 01532

or visit our Web site at

http://ma.water.usgs.gov
Con

CONTENTS

Executive Summary...........................................................................................................................................................

Abstract .............................................................................................................................................................................

Introduction .......................................................................................................................................................................

Design Considerations for a Statewide Monitoring Network ...........................................................................................

Monitoring Objectives.............................................................................................................................................

Monitoring Approaches...........................................................................................................................................

Ongoing Monitoring Activities by State Agencies in Massachusetts......................................................................

Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assessment...............................................

Tier I Monitoring Program Objectives and Approaches .........................................................................................

Tier I Monitoring Design for the Neponset River Basin .........................................................................................

Definition of Water Resources in the Basin ..................................................................................................

Data Sources........................................................................................................................................

Streams ................................................................................................................................................

Lakes ...................................................................................................................................................

Sampling Designs..........................................................................................................................................

Exhaustive Approach...........................................................................................................................

Sampling Sites, Parameters, and Frequency .............................................................................

Resource Requirements.............................................................................................................

Analysis of the 1994 Neponset Water-Resource Assessment ................................................................................

Combined Probabilistic-Deterministic Approach ...................................................................................................

Sampling Sites, Parameters, Frequency, and Resource Requirements for Streams ......................................

Probabilistic Sampling Program..........................................................................................................

Deterministic Sampling Program ........................................................................................................

Sampling Sites, Parameters, Frequency, and Resource Requirements for Lakes .........................................

Statewide Implementation of the Combined Probabilistic-Deterministic Approach for Tier I 

Basin-Based Monitoring .................................................................................................................

Tier II: Fixed-Station Monitoring Program for Contaminant Loads in Major Rivers.......................................................

Sampling Sites, Parameters, and Frequency ...........................................................................................................

Resource Requirements...........................................................................................................................................

Tier III: Targeted Monitoring Programs............................................................................................................................

Tier V: Strategies for Compliance-Based Ambient Monitoring ........................................................................................

Summary and Conclusions................................................................................................................................................

References .........................................................................................................................................................................

Appendix: Geographic Information System (GIS) and other computer-based procedures used in

the monitoring design for the Neponset Basin ....................................................................................................

FIGURES

1. Diagram showing types of monitoring ..............................................................................................................

2. Map showing the Neponset Basin in eastern Massachusetts.............................................................................

3. Diagram showing criteria for segmenting stream hydrography for Tier I monitoring in the 

Neponset Basin ..................................................................................................................................................

4. Maps showing perennial streams by stream order and lakes inventoried for Tier I monitoring in the 

Neponset River Basin ........................................................................................................................................

5. Diagram showing total perennial stream miles in the Neponset Basin and assessed miles by stream 

order and designated use from the 1994 Neponset water-resource assessment ................................................

6–8. Maps showing:

6. Locations and watershed-drainage areas of proposed sites for Tier II monitoring ...................................

7. Sites sampled for bacteria for hot-spot monitoring in the 1994 Neponset water-resource 

assessment and generalized land use in the basin .....................................................................................

8. Locations and watershed-drainage areas of permitted major discharge sites within the National 

Pollutant Discharge Elimination System in Massachusetts for potential water-quality monitoring.........
IV Contents

TABLES 

1. Ongoing water-quality monitoring in Massachusetts by State agencies and programs......................................

2. Selected surface-water quality standards and criteria for determining use-support status in 

Massachusetts streams ........................................................................................................................................

3. Discharges permitted under the National Pollutant Discharge Elimination System that were used in 

defining stream segments for Tier I monitoring in the Neponset Basin .............................................................

4. Summary statistics for stream miles and segments inventoried for Tier I monitoring in the 

Neponset Basin ...................................................................................................................................................

5. Physical characteristics of lakes inventoried for Tier I monitoring in the Neponset Basin ................................

6. Sampling parameters and frequency for an exhaustive approach to Tier I monitoring in the Neponset 

Basin ...................................................................................................................................................................

7. Resource requirements for an exhaustive approach to Tier 1 monitoring in the Neponset Basin ......................

8. Sampling parameters and frequency for a combined probabilistic-deterministic approach to Tier I 

monitoring in the Neponset Basin.......................................................................................................................

9. Resource requirements for a combined probabilistic-deterministic approach to Tier 1 monitoring in the 

Neponset Basin ...................................................................................................................................................

10. Sampling sites and drainage areas for Tier II monitoring to determine loads carried by major rivers in 

Massachusetts .....................................................................................................................................................

11. Distribution of major discharge sites within the National Pollutant Discharge Elimination System among 

major river basins and stream orders in Massachusetts ......................................................................................

CONVERSION FACTORS AND WATER-QUALITY INFORMATION 

CONVERSION FACTORS

WATER-QUALITY INFORMATION

Concentrations of chemical constituents are given in milligrams per liter (mg/L). Milligrams per liter

are units expressing the concentration of a chemical constituent in solution as weight (milligrams) of

solute per unit volume (liter) of water. For concentrations less than 7,000 mg/L, milligrams per liter is

equivalent to “parts per million.” 

Multiply By To obtain

acres 0.4047 hectares

feet (ft) 0.3048 meters

miles (mi) 1.609 kilometers

square miles (mi2) 12.590 square kilometers

Temperature is given in degrees Fahrenheit (oF), which can be converted to

degrees Celsius (oC) by the following equation: oC = (oF-32)/1.8
Executive Sum

EXECUTIVE SUMMARY

Problem

Public agencies tasked with protecting and 

managing water resources need information from 

water-quality monitoring for many purposes. 

Information is needed to assess the current “health” 

of water bodies with respect to water-quality standards, 

to design and evaluate remediation programs, to 

document compliance with regulations, to detect 

trends in water quality, to identify emerging problems, 

and to increase community awareness of waterresource protection. In Massachusetts, several State 

and Federal agencies and many volunteer groups 

conduct water-quality monitoring, but their programs 

do not always provide data at the spatial or temporal 

scales necessary to meet these information needs. For 

example, only 18 percent of total stream miles and 48 

percent of lake acres were reported as assessed in the 

State’s 1998 Summary of Water Quality [305(b)] 

report, and statewide trends cannot be determined from 

the existing data (Commonwealth of Massachusetts, 

1997, 1998). Previous statewide data-collection 

programs have been biased towards larger rivers, 

known problem areas, and point pollution sources; in 

this way, the programs have provided limited spatial 

coverage and have not adequately depicted waterquality conditions throughout the State. A statewide 

strategy for water-quality monitoring is needed to 

provide consistent and comprehensive water-quality 

data on waters throughout the Commonwealth. 

Overview

The U.S. Geological Survey worked with 

the Massachusetts Department of Environmental 

Protection, Division of Watershed Management 

(DEP/DWM) to design a water-quality monitoring program for Massachusetts. The program design was 

guided by the information needs of the DEP/DWM, 

which include mandates of the Clean Water Act (CWA) 

and activities of the Massachusetts Watershed Initiative 

(MWI), and by input from many organizations 

involved in water-quality monitoring in the Stat

be effective, a monitoring program must be des

to fulfill the purposes for which the data will be 

Thus, the proposed program for Massachusetts’ 

ple information needs has several components o

that are defined by specific monitoring objectiv

• Tier I—Basin-Based, Statewide Water-Qualit

Assessment: To provide a periodic assessm

the water-quality status of the State’s surfa

waters, as required by section 305(b) of the 

implemented on a 5-year, rotating-basin ba

the MWI basin assessments;

• Tier II—Contaminant Loads: To determine lo

of contaminants carried by major rivers in 

Massachusetts at strategic locations, such a

mouths of major rivers and at State bounda

• Tier III —Targeted Monitoring, Spatially or b

To identify impaired water bodies required 

section 303(d) of the CWA, to determine c

and sources of impairments for purposes of 

and 305(b) requirements, to identify pollut

sources or “hot-spots,” and other site-speci

objectives;

• Tier IV—TMDLs: To develop Total Maximum 

Loads for specific water bodies.

• Tier V—Compliance monitoring: To meet reg

requirements and permits.

The program as described in this report is most 

developed for Tiers I and II, which are statewid

scale, and resource requirements for implement

these tiers are discussed. Strategies for Tier III “

spot monitoring,” an objective of the MWI team

are investigated. Strategies for Tier IV, TMDL 

development and monitoring in Massachusetts, 

being developed separately and are not discusse

this report. Finally, a network is investigated tha

use compliance monitoring under the National 

Pollutant Discharge Elimination System as a po

fifth Tier in the program. 

Statewide Water-Quality Network for Massachusett
VI Executive Summary

Design Considerations

To guide the monitoring program design, a 

review was conducted of general principles of 

network design, including monitoring objectives and 

approaches, and of ongoing monitoring activities of 

Massachusetts State agencies. A clear definition of 

objectives for the monitoring program is a first and 

necessary step in network design. Monitoring 

approaches, which comprise the details of how waterquality measurements will be made, are chosen to 

answer the water-quality questions posed by the program objectives. Monitoring approaches can be defined 

in terms of the time period of the measurements (shortterm, long-term, or rotating), the method of site selection (targeted or probabilistic), the types of measurements made (for example, physical, chemical, or 

biological), the type of water resource being monitored 

(for example, stream, lake, or ground water), and the 

use of the monitoring results. Monitoring methods 

include fixed-station monitoring, which is a type of 

monitoring in which the same sites are repeatedly 

sampled at regular intervals, for a long period of time. 

Fixed-station monitoring and flow data typically are 

needed to estimate mass fluxes or constituent loads, as 

in Tier II of the proposed monitoring program; this is 

not the best approach for a large-scale assessment of 

water-resource conditions, as is needed for Tier I of the 

proposed program. Short-term (synoptic) surveys that 

incorporate probabilistic designs are more appropriate 

for large-scale assessments. 

Ongoing monitoring programs by State agencies 

include (1) lake sampling, fish-toxics monitoring, 

benthic macroinvertebrate measurements, and some 

water-chemistry monitoring by DEP/DWM, (2) lake 

monitoring by DEM in State parks, (3) reservoir, reservoir tributary, and coastal river sampling for bacteria 

and water-chemistry by the Metropolitan District 

Commission and the Massachusetts Water Resources 

Authority, (4) bacteria and physical monitoring in 

coastal waters by the Division of Marine Fisheries and 

fish community surveys by the Division of Fisheries 

and Wildlife of the Department of Fisheries, Wildlife, 

and Environmental Law Enforcement, (5) groundwater monitoring for highway-runoff contaminants 

by the Massachusetts Highway Department, and 

(6) diverse monitoring activities of many local volunteer groups. Many of these activities would provide 

useful data for components of the statewide monitoring 

program, but none has the monitoring approach, 

geographic coverage, sampling density, or sampling 

parameters that would provide information to m

the information needs of DEP/DWM, the MWI 

and the U.S. Environmental Protection Agency. 

review of ongoing monitoring programs demon

the need for the development of a statewide mon

program. 

Statewide Water-Quality 

Network Design

Tier I—Basin-Based, Statewide 

Water-Quality Assessment

The proposed monitoring program develo

Tier I objectives consists of a basin-based asses

of existing surface-water-quality conditions wit

respect to State water-quality standards and the 

nated uses of water bodies. Requirements for a 

program, reflecting CWA mandates, are that it b

wide in scale, comprehensive (all water bodies 

Commonwealth are assessed), and repeated at r

intervals. Another goal is that the program lead 

improvements in the 305(b) assessment, by incr

the number of stream miles and lake acres asses

reducing the historical bias toward problem are

Monitoring for Tier I objectives would be imple

on a 5-year, rotating basin basis, reflecting the S

strong commitment to the watershed approach. 

approaches for this tier were investigated by use 

information collected in the Neponset Basin in 

Massachusetts. This basin was also used as a pi

for the MWI in the early 1990s. The Neponset B

a 117-square-mile watershed with urban (19 pe

residential (35 percent), and forested or undeve

(48 percent) land uses that drains to Boston Har

Geographic Information System (GIS) pr

dures were developed to inventory streams and 

the Neponset Basin for a comprehensive assess

using the 1:25,000-scale centerline hydrography 

Watershed Tools of the Massachusetts Office of 

graphic and Environmental Information (MassG

The basin contains 152 miles of perennial strea

46 lakes larger than 5 acres for inclusion in the 

ment. About 50 percent of stream miles were fir

order, or small headwater, streams; about 35 pe

were second- or third-order streams, many of w

drain major tributary subbasins; and about 15 p

were fourth- and fifth-order streams, primarily p

the mainstem Neponset and East Branch Nepon

Rivers. 
Executive Sum

In order to investigate an exhaustive approach to 

assessment, stream miles in the basin were segmented 

on the basis of physical features (confluences with tributaries, lakes, and point discharges) that could potentially alter water quality. Lakes were assessed as 

discrete water bodies. Resources required for an 

exhaustive approach, in which all stream segments and 

lakes in the Neponset Basin are assessed and data are 

collected to evaluate nearly all applicable water-quality 

standards, were estimated to be about 2,660 personneldays or 12 full-time equivalents (FTEs) for field sample 

collection and processing and about 4,700 laboratory 

analyses. The Neponset Basin, areally less than onehalf of the Boston Harbor Watersheds Basin, is small 

compared to the 27 major basins in Massachusetts, 

which average about 300 mi2 in area (about 400 mi2

when basins are combined for MWI teams). Thus, the 

resource estimates for the Neponset Basin probably 

represent at best about one-half of the resources needed 

for an exhaustive assessment of a typical major basin. 

For statewide implementation with the MWI, in which 

five major basins are assessed per year, perhaps 10 

times the Neponset estimates would be needed, or 

about 120 FTEs for sample collection and processing 

and about 47,000 analyses; in all likelihood, more than 

double the personnel resources would be needed when 

project planning, field preparation, data management 

and analysis are included. Thus, resource requirements 

for a comprehensive assessment of all water bodies 

using this exhaustive approach are much greater than 

could be realistically expended.

The monitoring program and results of the 1994 

Neponset assessment were reviewed for comparison 

with the goals and requirements of a comprehensive 

assessment, such as the exhaustive approach described 

above. The 1994 study was an in-depth assessment of 

water resources in the Neponset River Basin, with multiple objectives in addition to that of a basin-wide 

(though not comprehensive) use-support assessment 

for the CWA. During that study, about one-half of the 

total stream miles in the basin were assessed for their 

designated uses, with a sampling density that was considerably less than that proposed for a systematic, 

exhaustive assessment of streams and lakes in the 

basin. All fourth- and fifth-order streams were assessed 

for most designated uses; the fraction of third-order 

streams assessed varied from 15 to 85 percent, by use; 

and less than one-half of second-order streams and less 

than one-third of first-order streams were assessed for 

any use. About one- to three-fourths of significant 

(larger than 5 acres in area) lakes in the basin were 

assessed for designated uses; lake assessments 

based on limited data that resulted in only impa

being assessed for important uses of aquatic life 

primary contact recreation. 

Analysis of the Neponset Basin hydrograp

1994 study demonstrated that resource-limitatio

lems will always be posed by the large number 

needed in order for all the small streams in a bas

sampled and the need for repeated site visits to 

some uses. Thus, a monitoring program is prop

which (a) probabilistic monitoring of small stre

combined with the deterministic or targeted mon

of large streams and (b) deterministic or probab

monitoring of lakes may be supplemented with 

intensive sampling in lakes of special interest. S

streams, including first-, second-, and third-ord

streams, are assessed probabilistically for the aq

life and recreational uses with biomonitoring an

bacteria sampling. This approach is proposed to 

the CWA requirement of 100 percent coverage 

small streams. Estimates of use support would b

vided for all small streams as a group, rather th

definitive information for individual streams, an

causes or sources of impairments could not be i

fied. Depending on the resources expended, com

hensive estimates of these uses for small stream

be made on a statewide basis only or for individ

basins. For large streams, including fourth-, fift

some third-order streams, nearly all designated 

would be assessed, with biomonitoring and sam

for water chemistry, bacteria, sediment, and fish 

All large streams in a basin would be assessed u

fixed sampling distance of about 5 miles per sam

This approach is proposed to meet DEP/DWM’

for information on water-quality conditions on 

reaches of these streams. Lakes greater than 10 

are assessed for aquatic life use and trophic statu

field parameters, macrophytes, Secchi-disk, nut

and chlorophyll-a sampling. 

The combined probabilistic-deterministic 

gram would provide information to meet CWA 

ments and provide data for other information ne

Massachusetts regulatory agencies and MWI te

would be implemented on schedule with the 5-y

rotating-basin cycle of the MWI, probably in th

MWI’s research and assessment years. Manage

level decisions would be needed with respect to 

gram objectives and sampling density for the pr

listic component of the program, about whether 

estimates of use support are needed for small st

on the statewide scale only or for individual bas
VIII Executive Summary

also. These decisions would affect resource requirements, but with the statewide estimate for small 

streams only, about 30 FTEs for field sample collection 

and processing and about 10,500 laboratory analyses 

would be needed; this assumes that five basins, each of 

which requires about twice the effort as the Neponset, 

are assessed per year. Additional time for field preparation and data management could double these requirements to about 60 FTEs, with several additional FTEs 

needed for program administration, planning, site 

selection, and obtaining permissions.Although they are 

much less than the requirements for the exhaustive 

approach, these resource requirements are substantial. 

They could be reduced by eliminating or reducing 

assessment of some designated uses that require intensive sampling, such as the recreational use for small 

streams or frequent sampling of lakes for trophic status, 

or by using a probabilistic approach for lakes. 

Volunteer monitoring could be used in several 

ways to enhance the proposed program for Tier I monitoring or to offset the resource requirements for field 

data collection. Volunteer monitoring, coordinated 

through the MWI teams, could be used to conduct 

biomonitoring or collect bacteria samples at additional 

sites in basins where individual status estimates for 

small streams are needed; these estimates could be less 

rigorous if less sophisticated biomonitoring protocols 

were followed by the volunteer groups than by agency 

personnel. Volunteer monitoring of additional sites on 

large streams could be used to increase the number of 

third-order streams that are deterministically monitored, or to increase the sampling density on mainstem 

reaches, most likely for aquatic life (water chemistry 

sampling) or recreational (bacteria sampling) uses. For 

lakes, volunteer monitoring could be used to increase 

or maintain the measurement frequency for trophicstatus indicators, to conduct more intensive assessments for some lakes, or to sample lakes of special 

interest deterministically if a probabilistic approach for 

lakes generally is taken. 

Tier II—Contaminant Loads in Major Rivers

Tier II is a fixed-station sampling network to 

determine contaminant loads carried by major rivers. 

Nineteen sampling sites, in 17 of the 27 major basins in 

Massachusetts, are proposed. Because continuous 

streamflow records are needed for accurate loads calculations, the sites are located primarily at or near existing streamflow gages. The proposed sampling sites are: 

near the mouths of the Merrimack, Aberjona, Charles, 

Ipswich, Neponset, and Taunton Rivers, which 

tively drain to Boston Harbor, the Gulf of Main

Narrangansett Bay; at the mouths of the Millers

field, Chicopee, and Westfield Rivers, which dis

to the Connecticut River; at the mouths of the C

and Nashua Rivers, which discharge to the Mer

River; and at locations on the Quinebaug, Frenc

Blackstone, West Branch Farmington, Housaton

Connecticut Rivers near where they enter and(o

the State. Sampling at these sites would provide 

mation on contaminant loads from 67 percent o

total land area of the State. The remaining unsa

areas of the State would be primarily coastal ar

which are drained by numerous small streams. 

Resource limitations would preclude including 

these streams in a loads network. A limited num

sites in small coastal watersheds also could be s

for a sufficient time (several years) to character

loads from the watersheds, however, and then d

tinued and re-located elsewhere in the coastal a

Loads from some areas, between the coast and 

inland limit of tidal influence, will not be determ

without developing site-specific, non-standard m

for flow measurement (through dams, for exam

or modelling. Sampling parameters for Tier II m

ing, proposed to provide information on the wa

quality issues of concern for receiving waters o

specific site locations, include field parameters, 

ria, nutrients, suspended sediment, and possibly 

at some sites. Sampling frequency is determined 

need to characterize adequately the range of hyd

and seasonal conditions for loads calculations. T

about 15 samples per year are proposed, at abou

monthly intervals but also during high and low 

The sampling frequency could be enhanced by 

use of volunteers or paid observers. Volunteer m

ing would be particularly useful for sediment an

sediment-borne contaminants, because frequent 

sampling is needed to adequately quantify sedim

loads. Resource requirements for Tier II of the n

were estimated at about 2 FTEs for water-quali

sample collection, with additional time needed f

preparation, data analysis and management, and 

resources for the installation, operation, and ma

nance of any new streamflow gages. 
Executive Sum

Tier III—Targeted Monitoring 

Programs

Targeted programs of Tier III of the proposed 

network are described primarily in terms of strategies 

for hot-spot monitoring, that is, monitoring to identify 

pollution sources. These strategies are investigated 

using an analysis of the bacteria sampling program of 

the 1994 Neponset Basin assessment. In that study, 

data from 41 sites were used to identify leaking sewer 

lines and failed septic systems, as well as stormwater 

runoff, as general sources of bacteria contamination in 

the basin and to confirm that bacteria were a basinwide problem. The bacteria source for a specific 

impaired reach was identified in only one instance out 

of 29 impairments, using infrastructure investigation 

by a town rather than by additional water-quality 

sampling. An analysis of watershed areas of the 

sampling sites found little relation between bacteria 

concentrations and land uses expected to be bacteria 

sources. These analyses illustrate the difficulties that 

can arise when a single monitoring design is used to 

address multiple, sometimes partly conflicting, monitoring objectives. They also demonstrated that effective 

programs for hot-spot monitoring are based on substantial knowledge of suspected problem areas and on site 

and contaminant characteristics, information that commonly is compiled by MWI teams and also could be 

provided to some extent by Tier I of the monitoring 

program. Monitoring data at all quality levels and the 

local knowledge of volunteer groups also could be very 

effective for site selection or source identification. 

Once known or suspected hot spots are identified, sitespecific sampling programs in terms of sampling 

parameters and density can be designed. Because 

these programs are issue-, site-, and basin-specific, 

resource requirements for an effective program for this 

component of Tier III of the network cannot be defined 

in advance. 

Tier V—Strategies for Compliance-Based 

Ambient Monitoring

The distribution of major National Pollutant 

Discharge Elimination System (NPDES) sites in 

Massachusetts was evaluated to determine the usefulness of these sites for the collection of ambient waterquality data. Locations of 155 sites were reviewed. 

The sites were well distributed geographically among 

basins, but were located primarily on large rivers, 

with two-thirds or more on fourth- or higher order 

streams. Use of these sites for a statewide assessment 

of stream-water quality, such as needed for Tier 

monitoring program, would yield estimates of u

port that were biased towards large streams. Th

geted approach to site selection also would mea

monitoring could not be extrapolated to unsamp

streams. Thus, with assumptions of 3 miles of a

stream per site for first- through third-order stre

and 5 miles per site for fourth- and higher order 

streams, a total of 553 miles, or less than 10 per

of the perennial stream miles in the State, woul

assessed by sampling major NPDES sites. NPD

sites might be more suited to sampling for loads 

II objectives than for a statewide status assessm

Watersheds of major NPDES sites, where they 

be determined, account for about 70 percent of t

land area of Massachusetts. These sites may no

optimally located in terms of the loads objective

ever, and would require review; the isokinetic d

and flow-integrated sampling needed for loads c

tions also generally is best implemented by exp

enced water-quality personnel. Moreover, it mig

difficult to adequately design and implement pr

for sample collection, handling, and analysis by 

ple private entities to ensure data of sufficient co

bility and quality to meet statewide information 

Summary

The water-quality monitoring program de

in this report contains several components that 

provide information to meet many of the water-

information needs of the Massachusetts state ag

and others concerned about water resources in t

State. The components are complementary in m

ways but are not interchangeable, and each com

requires a substantial investment of personnel ti

laboratory analyses, and other resources. Severa

ponents must be developed on site-specific base

available resources will place important constra

all aspects of the program. The water-quality in

tion needs to which components of the propose

gram are addressed must be carefully evaluated 

prioritized, so that monitoring resources are effi

and effectively deployed in accordance with the 

tasks of protecting and managing the water reso

of Massachusetts. 

Ab

Statewide Water-Quality 

Network for Massachusetts

By Leslie A. DeSimone, Peter A. Steeves, and Marc J. Zimmerman

Abstract

A water-quality monitoring program is 

proposed that would provide data to meet multiple 

information needs of Massachusetts agencies and 

other users concerned with the condition of the 

State’s water resources. The program was 

designed by the U.S. Geological Survey and the 

Massachusetts Department of Environmental 

Protection, Division of Watershed Management, 

with input from many organizations involved in 

water-quality monitoring in the State, and focuses 

on inland surface waters (streams and lakes). The 

proposed monitoring program consists of several 

components, or tiers, which are defined in terms 

of specific monitoring objectives, and is intended 

to complement the Massachusetts Watershed 

Initiative (MWI) basin assessments. Several components were developed using the Neponset River 

Basin in eastern Massachusetts as a pilot area, or 

otherwise make use of data from and sampling 

approaches used in that basin as part of a MWI 

pilot assessment in 1994. To guide development of 

the monitoring program, reviews were conducted 

of general principles of network design, including 

monitoring objectives and approaches, and of 

ongoing monitoring activities of Massachusetts 

State agencies. 

Network tiers described in this report are 

primarily (1) a statewide, basin-based assessment 

of existing surface-water-quality conditions, and 

(2) a fixed-station network for determining contaminant loads carried by major rivers. Other 

components, including (3) targeted programs for 

hot-spot monitoring and other objectives, and (4) 

compliance monitoring, also are discussed. 

Monitoring programs for the development o

Maximum Daily Loads for specific water b

which would constitute another tier of the n

work, are being developed separately and a

described in this report. The basin-based as

ment of existing conditions is designed to p

information on the status of surface waters 

respect to State water-quality standards and 

designated uses in accordance with the repo

requirements [Section 305(b)] of the Clean 

Act (CWA). Geographic Information System 

(GIS)-based procedures were developed to 

tory streams and lakes in a basin for these p

poses. Several monitoring approaches for th

and their associated resource requirements 

investigated. Analysis of the Neponset Basi

this purpose demonstrated that the large num

sites needed in order for all the small stream

basin to be sampled (about half of stream m

the basin were headwater or first-order strea

pose substantial resource-based problems fo

comprehensive assessment of existing cond

The many lakes pose similar problems. Thu

design is presented in which probabilistic m

ing of small streams is combined with deter

tic or targeted monitoring of large streams a

lakes to meet CWA requirements and to pro

data for other information needs of Massach

regulatory agencies and MWI teams. 

The fixed-station network is designed 

permit the determination of contaminant loa

ried by the State’s major rivers to sensitive 

and coastal receiving waters and across Sta

boundaries. Sampling at 19 proposed sites i

of the 27 major basins in Massachusetts wo

provide information on contaminant loads f
2 Statewide Water-Quality Network for Massachusetts

67 percent of the total land area of the State; 

unsampled areas are primarily coastal areas 

drained by many small streams that would be 

impossible to sample within realistic resource 

limitations. Strategies for hot-spot monitoring, a 

targeted monitoring program focused on identifying contaminant sources, are described with reference to an analysis of the bacteria sampling 

program of the 1994 Neponset Basin assessment. 

Finally, major discharge sites permitted under the 

National Pollutant Discharge Elimination System 

(NPDES) were evaluated as a basis for ambient 

water-quality monitoring. The discharge sites are 

well distributed geographically among basins, but 

are primarily on large rivers (two-thirds or more 

on fourth- or higher order streams). Thus, NPDES 

sites alone would provide a biased estimate of 

existing water-quality conditions, but might be 

useful for some loads determinations if data of 

sufficient quality could be collected. 

INTRODUCTION

Public agencies tasked with protecting and 

managing water resources, the natural environment, 

and public health have a critical need for information 

that is gained through water-quality monitoring. Information from water-quality monitoring is needed to 

assess the existing conditions of water resources, to 

design preservation, management, and remediation 

programs, and to evaluate the effectiveness of those 

programs (Intergovernmental Task Force on Monitoring Water Quality, 1995a). Monitoring also is needed to 

document compliance with State, Federal, and local 

regulations and permits. In addition, the results of 

water-quality monitoring are needed to detect and 

define trends in water quality, to identify emerging 

water-quality problems or problem areas, and to 

increase community awareness of and involvement 

in water-resource protection.

In Massachusetts, several State and Federal 

agencies conduct water-quality monitoring for 

various purposes related to their agencies’ missions. 

In addition, many watershed and lake associations 

monitor stream- and lake-water quality in many of the 

State’s 27 major river basins. Examples of existing 

State agency programs include (1) monitoring of 

benthic macroinvertebrates for aquatic life use-support 

determinations in five watersheds per year by th

Division of Watershed Management (DWM) of 

Department of Environmental Protection (DEP)

(2) lake-quality monitoring in State-owned lake

the Office of Water Resources of the Departmen

Environmental Management (DEM), (3) bacter

and nutrient monitoring in Boston Harbor and i

major tributary rivers by the Massachusetts Wat

Resources Authority (MWRA), and (4) contam

monitoring in shellfish by the Division of Marin

Fisheries (DMF) and fish community monitorin

the Division of Fisheries and Wildlife (DFW) o

Department of Fisheries, Wildlife, and Environ

Law Enforcement (DFWELE). Watershed assoc

such as the Charles and Neponset River Waters

Associations also monitor ambient stream-wate

quality by measuring field parameters, bacteria

nutrients at locations throughout their watershed

associations often maintain long-term records o

quality parameters such as Secchi-disk depth an

aquatic-plant cover. 

Existing agency and volunteer monitorin

grams, although numerous and well suited to th

individual purposes, do not always provide the 

types of data at spatial or temporal scales neces

meet many of the water-quality information nee

Massachusetts. For example, only 18 percent of 

stream miles and 48 percent of lake acres were r

as assessed in the State’s 1998 Summary of Wa

Quality [305(b)] report, and statewide trends ca

determined from the existing data (Commonwe

Massachusetts, 1997, 1998). Previous statewide 

collection programs have been biased towards l

rivers, known problem areas, and point pollutio

sources; in this way, the programs have provide

ited spatial coverage and have not adequately d

water-quality conditions throughout the State. M

watershed associations and other volunteer grou

collect monitoring data, but their activity is une

distributed statewide and often is limited to sma

and to a small number of water-quality paramet

Finally, the lack of mechanisms to link monitor

results, such as common systems for site locatio

data storage, documentation, or reporting, make

difficult to coordinate existing programs or to 

aggregate their results into larger-scale assessm

Consistent and comprehensive water-qual

at the state- and basin-wide scales are needed (

meet the State’s assessment and reporting requir

under the Federal Clean Water Act (CWA), (2) 
Introd

support the assessment and remedial activities of the 

Executive Office of Environmental Affairs (EOEA) 

Massachusetts Watershed Initiative (MWI) teams and 

to allow for comparison of water-quality conditions 

among major basins, and (3) to evaluate the effectiveness of large-scale pollution prevention and remediation programs. Scientifically valid and defensible sitespecific data also are needed by statewide programs 

to identify impaired water bodies and to support the 

development of Total Maximum Daily Loads (TMDLs) 

for impaired waters. Finally, information is needed on 

pollutant loads carried by major rivers to sensitive 

receiving waters and across State boundaries and 

on how these loads may be changing with time. To 

address these multiple information needs, the 

DEP/DWM worked with the U.S. Geological Survey 

(USGS) to design a comprehensive statewide waterquality monitoring strategy for Massachusetts. The 

DEP/DWM is the state agency tasked with monitoring 

and regulatory activities regarding water quality in the 

State’s major basins (Massachusetts Department of 

Environmental Protection, 1997). 

As an initial step in developing a statewide 

monitoring strategy, the USGS and DEP/DWM circulated a draft plan that outlined goals, objectives, and 

preliminary approaches of the proposed program 

among State and Federal agencies and other organizations involved in monitoring in Massachusetts. This 

plan contained eight general objectives for the network, 

which were to provide information for (1) definition 

of existing water resource conditions, (2) detection 

and definition of trends in concentrations, loads, and 

habitat, (3) calibration and validation of models, 

(4) evaluation of management strategies and program 

effectiveness, (5) detection of emerging problems, 

(6) design of abatement, control, and management 

strategies, (7) regulatory needs, including CWA, 

TMDLs, and enforcement, and (8) watershed teams. 

The plan’s scope included network design and data collection along with data management and reporting; its 

approach included five separate components, including 

statewide fixed-station sampling, basin-wide rotatingsite sampling in conjunction with MWI teams, sitespecific and issue-specific sampling, and volunteer 

sampling. This draft plan was subsequently revised 

to focus the monitoring program on the objectives 

defined by the CWA and other statewide water-quality 

information needs, and to limit its scope primarily to 

network design. The Neponset River Basin in e

Massachusetts was chosen as a pilot area for de

ing the basin-based components of the network 

This report describes several proposed co

nents of a comprehensive statewide water-quali

monitoring program for Massachusetts. These c

nents were developed by the USGS and DEP/D

from 1998 to 2000. A basin-based monitoring d

developed for the Neponset Basin, could be imp

mented across the State to meet requirements o

Federal CWA and other large-scale water-qualit

mation needs. A fixed-station network could be 

determine loads of contaminants delivered by th

State’s major rivers. A review of monitoring str

for identifying pollution sources, or “hot-spot 

monitoring”, which is an objective of the MWI 

incorporates further analysis of data from the N

basin. Finally, an analysis is presented of water

quality monitoring network that would make us

compliance monitoring conducted under the Na

Pollutant Discharge Elimination System (NPDE

requirements. 

In several sections of this report, estimate

resources required are presented, primarily in te

personnel and laboratory analyses, to implemen

monitoring programs as described. Aspects of th

itoring program that could be enhanced by the u

volunteer monitors also are identified; these asp

generally are consistent with recommendations 

recent report to EOEA on volunteer monitoring 

and others, 2000). It should be noted that the ag

personnel and laboratory estimates are based on 

assumptions about the personnel requirements o

specific sampling tasks. The resource estimates 

presented for comparison of monitoring progra

ponents and alternatives, and to describe the ma

of the proposed effort. They are not intended to 

as rigorous, quantitative evaluations. Finally, ad

resources for planning, data management, data 

sis, and coordination with volunteer groups, if u

would be needed to implement fully the propos

monitoring programs; estimates of these additio

resources are inherently more uncertain than pe

and laboratory estimates. 

The monitoring strategies described in th

report are limited to inland surface waters for se

reasons. Although within the scope of the Clean 

Water Act (which generally is within DEP/DWM

mandate), State agencies other than DEP/DWM 

responsibility for coastal monitoring in Massac
4 Statewide Water-Quality Network for Massachusetts

Monitoring of drinking-water quality is conducted 

under an existing, well-defined program within DEP 

with separate Federal and State regulatory requirements. Ambient ground-water monitoring, while an 

important part of a comprehensive water-resource 

monitoring program, is not currently planned in the 

State. Information is provided on these and other monitoring programs of State agencies, however, to facilitate future investigation of mechanisms for integrating 

these efforts into a comprehensive statewide strategy 

for water-quality monitoring in Massachusetts. 

DESIGN CONSIDERATIONS FOR A 

STATEWIDE MONITORING 

NETWORK

Monitoring Objectives

The first step in the design of any water-quality 

monitoring program is to define the objectives of the 

monitoring activity. Monitoring objectives also may be 

represented as information needs, the fulfillment of 

which allows water-quality managers and others to 

make informed decisions about regulations, actions, or 

programs. General objectives of water-quality monitoring programs commonly are stated to include determining current water-quality conditions, detecting trends, 

identifying problems, and collecting data for model 

studies (Ward and others, 1990). However, because of 

the large inherent variability, both spatial and temporal, 

in water-quality conditions and because of the wide 

variety of parameters that can be measured as indicators of quality, monitoring objectives usually must be 

much more specifically defined than the commonly 

stated general objectives in order to design effective 

monitoring programs. Collecting data in advance of or 

without an identified information need, while appropriate for a fundamental and relatively simple parameter 

such as water quantity (that is, streamflow), is problematic for a highly variable and multifaceted characteristic such as water quality (R.P. Hooper, U.S. Geological 

Survey, written commun., 1996). 

Specific objectives of a monitoring program 

developed to meet the information needs of the 

DEP/DWM in Massachusetts can be derived from the 

regulatory mandates and statutory interests of th

agency1. As the state agency responsible for mo

ing and regulatory activities regarding inland w

quality, the DEP/DWM, with the U.S. Environm

Protection Agency, is responsible for implemen

Federal CWA in Massachusetts. For example, s

305(b) of the CWA requires that each State dev

water-quality monitoring program and periodic

report the status of its water quality (U.S. Envir

tal Protection Agency, 1997a). This assessment 

expected to be comprehensive, in that all surfac

bodies (streams, lakes, and coastal waters), as w

ground water, are included. Water-quality status 

this purpose is described in terms of the waters

ability for various uses, such as drinking water, 

swimming, and aquatic life; these uses are form

defined as “designated uses” in State and Feder

lations. Section 303(d) of the CWA requires that 

that do not meet applicable water-quality standa

after implementation of effluent-discharge cont

identified, and TMDLs be determined for these 

(U.S. Environmental Protection Agency, 1997a

DEP/DWM also has responsibility for supportin

MWI teams by conducting water-quality and bi

toring surveys in the second year of the MWI’s 

assessment and remedial cycles. DEP/DWM an

teams need this and other information to assess 

shed water-quality conditions (“health”) at the r

basin scale, to identify impaired waters and pol

sources (“hot spots”) at the reconnaissance level

determine the effectiveness of specific managem

actions (best management practices, or BMPs) 

basins. DEP/DWM and other state agencies als

an interest in determining the loads of and time

in pollutants delivered by large rivers to sensitiv

receiving waters, such as Boston Harbor, and ac

State boundaries. Finally, DEP/DWM, in conju

with USEPA, is responsible for regulating and d

mining compliance of surface-water discharger

NPDES permits. 

These information needs, defined by CW

dates, MWI requirements, and the other regulat

interests described above, define a set of objecti

which to build a comprehensive and adequate st

water-quality monitoring program. A program i

1A comprehensive monitoring strategy for the State would include objectives derived from the mandates and interests of all S

agencies and other organizations; although outside of the scope of the current effort, the survey information provided on monitorin

programs of other agencies, described in a subsequent section of the report, provides useful background information for this purpo
Design Considerations for a Statewide Monitoring Ne

 	


 


 





 


 


 





Long term or 

indefinite

(e.g., fixed stations)

Short term 

(e.g., surveys)

Rotating by basin

Physical

- flow

Chemical

- dissolved oxygen

- nutrients

- toxics

Biological

- macroinvertebrates

- fish community

- fish tissue

Pathogen

- indicator bacteria

- shellfish

Habitat

Toxicity testing

Stream

Lake

Ground water

Precipitation

Estuary

Marine water

Effluent

Status assess

Trends

Compliance

Enforcement

	 


 

Targeted

Probability based

proposed that consists of several components or “tiers,” 

that reflect the different spatial and temporal scales of 

the identified water-quality information needs and the 

different purposes, for example, regulatory or reconnaissance, for which the data are used. Tier I consists of 

monitoring for objectives defined by the 305(b) assessment, that is, the status of the State’s waters relative to 

applicable water-quality standards. Monitoring for this 

objective would be implemented on a 5-year, rotatingbasin basis, reflecting the State’s strong commitment to 

the watershed approach. Tier II consists of monitoring 

for pollutant loads and trends at the mouths of major 

rivers. Tier III consists of sampling that is targeted 

spatially or by issue, and includes data collection for 

303(d) listing of impaired waters, causes and sources of 

impairments for 303(d) and 305(b) purposes, “hotspot” monitoring, and other site-specific investigations. 

Tier IV consists of monitoring for TMDL development 

for specific water bodies. 

The monitoring program described in this report 

is most fully developed for Tiers I and II, which are 

statewide in scale. Monitoring designs for Tiers III and 

IV will vary significantly based on site characteristics 

and the purpose of the investigation. Thus, designs for 

these tiers generally are not suited for definitive development at the statewide scale. Strategies for TMDL 

development and monitoring in Massachusetts are 

being developed separately (D.R. Dunn, Massachusetts 

Department of Environmental Protection, writte

mun., 1999), and are not discussed in this repor

Monitoring for compliance with NPDES and ot

permits also is highly variable and site specific, 

closely tied to purposes defined by individual p

Compliance monitoring historically has been m

separately from most ambient monitoring progr

(Intergovernmental Task Force on Monitoring W

Quality, 1995a, b). The MWI approach, howeve

provides a link between water-resource assessm

compliance monitoring at the basin scale, and c

ance monitoring is a possible fifth tier in the pro

statewide monitoring program. An investigation 

potential links between ambient and complianc

toring at the statewide scale is provided in this r

through an analysis of the spatial distribution of 

NPDES dischargers in Massachusetts.

Monitoring Approaches

Monitoring approaches comprise the spec

of how water-quality measurements will be mad

to provide the information needed to meet mon

objectives. Monitoring activities/approaches ca

described in terms of five categories that also ca

considered as types of monitoring (fig. 1).

Figure 1. Types of monitoring (modified from Ward and others, 1990, p. 10–12, and U.S. Environmental Protection Ag

1997b, Appendix 1).
6 Statewide Water-Quality Network for Massachusetts

A specific monitoring approach contains elements from 

each of these monitoring-type categories, which are 

chosen to fit the water-quality questions posed by the 

monitoring objective. No single monitoring approach 

or type of monitoring can provide the data needed to 

address all water-quality information needs. 

Monitoring in which the same sites are repeatedly sampled, at regular time intervals, over an indefinite or long period of time, commonly is called fixedstation monitoring. This type of monitoring formed the 

basis of traditional water-quality networks, including 

the first phase of the U.S. Geological Survey’s National 

Stream Quality Accounting Network (NASQAN; R.P. 

Hooper, written commun., 1996; Hooper and others, 

1997). Fixed-station sampling is useful for long-term 

monitoring, for detection of trends, for assessment of 

larger streams, and for monitoring critical reaches of 

streams with regulated or permitted discharges. Fixedstation monitoring, with the collection of flow data, is 

essential for the calculation of contaminant loads by 

rivers, which may be needed at strategic locations such 

as State borders. However, fixed-station monitoring 

programs must be carefully designed with intended use 

of the data collected in mind. For example, if contaminant loads are needed, then the sampling schedule must 

be constructed such that the range of hydrologic conditions (high and low flows or seasonal variations) 

during which the specific contaminants of interest are 

transported are sampled; or, sampling must be frequent 

enough so that the relevant range of conditions can be 

subsequently determined. The number of samples 

collected within the time period of interest also must be 

adequate for statistically valid calculations. Special 

consideration must be given to contaminants that are 

associated with wet-weather flow, because sampling at 

periodic, fixed intervals may inadequately characterize 

loads and water-quality conditions that result from contaminant inputs that change rapidly during rainfallrunoff events. Finally, a trade-off exists between design 

requirements for the detection and interpretation of 

trends and for determining loads. Stations selected for 

loads determinations are likely to be located at the 

mouths of relatively large basins; however, large basins 

commonly are heterogeneous in land use and other 

factors affecting stream-water quality, making it difficult to relate trends detected at these sampling stations 

to specific causes or changes within the basins (Smith 

and others, 1987). A lack of high-quality, time-series 

data on factors affecting water quality also mak

ficult to identify the causes of trends that may b

detected.

Fixed-station monitoring generally is not 

single approach for a comprehensive assessmen

water resources at the state-wide or basin scale, 

several reasons. This type of monitoring require

long-term commitment of a large amount of res

which generally will severely limit the number 

stations that can be operated. With limited num

sampling stations, water-quality conditions mus

extrapolated for long distances up- and downstr

from the sampling site to obtain the spatial cove

necessary for state- or basin-wide assessments. 

extrapolation often is not valid, because many w

quality parameters (for example, dissolved oxy

bacteria, and contaminants associated with sedi

are not conservative—that is, they are subject to 

attenuation or transformation and can change ra

concentration downstream. Moreover, there ofte

multiple or even continuous inputs of contamin

along a stream reach that can change water-qua

conditions and make an extrapolation invalid. In 

addition, the resource limitations of fixed-statio

sampling often results in selecting sites on relat

high-order (that is, larger) streams. A network o

on large streams will not provide information o

quality in specific low-order (that is, smaller) tr

ies, but will only describe a cumulative water q

For example, a low-order stream may have seri

violations of water-quality criteria, but dilution 

contaminants in the larger stream may mask the

problems. 

Another approach, short-term monitoring

includes special studies that generally are direc

towards specific water-quality problems and syn

surveys that provide “snapshots” of water-quali

conditions over a wide area. The spatial coverag

provided by synoptic surveys, in which many si

are sampled, makes this type of monitoring use

areal assessments of existing conditions and ho

monitoring. Climatic, seasonal, and other tempo

variability in water quality conditions are impor

considerations for short-term monitoring progra

Short-term temporal variability in many water-q

constituents, such as dissolved oxygen and indi

bacteria, may mean that sites will need to be sa

repeatedly, even in synoptic surveys, to charact

the water-quality conditions of interest, or that t

sampling period must be carefully chosen, perh
Design Considerations for a Statewide Monitoring Ne

represent “worst case” conditions. Multi-year climatic 

variability may make it difficult to compare short-term 

monitoring results to historical data or data collected in 

other basins during different assessment years. 

Changes with time resulting from management practices or changing land uses also may be difficult to 

identify using short-term monitoring programs. 

Rotating-basin programs, in which intensive 

short-term surveys are conducted periodically in a 

watershed, may both provide wide spatial coverage and 

allow for the identification of changes in water-quality 

conditions with time. However, consistency of monitoring approaches, data-collection procedures, and 

laboratory analytical procedures are needed so that the 

results of sequential basin assessments are comparable. 

Climatic variability also may limit data comparability.

Methods of site selection define a category of 

monitoring types that also places important constraints 

on the uses of data collected from monitoring networks 

(fig. 1). A common method used in monitoring programs is the targeted approach whereby sites are 

selected for multiple, site-specific reasons. For example, in a recent USGS/DEP/EOEA monitoring program 

for streamflow and quality in an Eastern Massachusetts 

watershed, 45 possible sampling sites, of which 10 

were used, were proposed for the following reasons: 

(1) to determine the effects of likely problem areas or 

activities, such as septic tanks, stormwater, highway 

construction, and waste management; (2) to determine 

baseline conditions upstream of major known pollution 

sources; (3) to determine conditions at boundaries of 

subwatersheds; (4) to document conditions prior to 

remedial actions; (5) to determine conditions for fish 

passage and fishery-stream habitat; (6) to determine 

conditions in streams flowing to sensitive areas such as 

water supplies and State-designated Areas of Critical 

Environmental Concern; (7) to investigate reports of 

impaired quality; and (8) to confirm 303(d) listing of 

impaired waters. Data collected from programs such as 

this one can fill important information needs, such as 

identifying impaired waters and sources, identifying 

conditions and trends at specific sites, evaluating 

improvements due to specific management actions 

in a watershed, and, with biomonitoring, provide information on the biological response to water-quality 

stressors. However, results of such targeted sampling 

programs cannot easily be extended to unsampled sites, 

and so cannot provide comprehensive areal assessments of conditions throughout a basin or state. Without defensible information on the extent and severity of 

a water-quality problem at the statewide scale, i

be difficult to justify the expenditure of resource

large-scale remediation or control (U.S. Environ

Protection Agency, 1997b).

Probability-based approaches are alternat

targeted sampling programs capable of providin

prehensive assessments of water-quality conditi

throughout an area. In these approaches, represe

sampling sites are chosen and conditions in the 

population of the water resource are inferred fro

monitoring results for these sites. In a probabili

based approach, sites are selected randomly fro

total population of a water-resource type in an a

example, from all streams or lakes in a watersh

state). Because the sites are selected randomly, 

toring results can be extrapolated to estimate co

tions in the total population with a known statis

confidence (U.S. Environmental Protection Age

1997b). In a stratified-random approach, the pop

of water bodies is divided into categories, for ex

by size or geographic area, and sites are random

selected from within these categories. This appr

could provide better estimates of conditions in e

category, because the variability within the cate

is less than in the entire population; it also allow

sampling procedures to be varied among catego

The probability-based approach is advant

in that it could provide an unbiased, comprehen

assessment of the status of a State’s water bodie

required by section 305(b) of the CWA. This ap

also could provide more information on the Sta

small streams, and on water bodies generally th

not expected to be affected by large pollution so

However, a probability-based approach cannot p

information on specific sites (unless they happe

included in the random selection) for document

impairments, for identifying new problem areas

detecting trends or evaluating improvements (U

Environmental Protection Agency, 1997b). Mon

resource limitations may result in a small numb

selected sampling sites, such that the confidenc

around the statewide estimates are large. Moreo

because an estimate of the water-quality status 

entire resource by itself cannot provide informa

the sources or causes of impairment, the inform

provided by a probability-based approach may 

limited use to managers in their efforts to impro

water quality. In addition, logistical difficulties, 

terms of accessing the randomly selected sites, 
8 Statewide Water-Quality Network for Massachusetts

arise that unexpectedly increase the personnel costs of 

the program when probability-based approaches are 

implemented. 

Another alternative for a comprehensive assessment of a water resource is a deterministic or exhaustive monitoring approach, in which all water bodies in 

an area are sampled or otherwise surveyed. This is a 

kind of targeted approach, but with no discrimination 

among potential sampling sites. In most cases, this 

approach will be severely affected by resource limitations. For example, sampling all 8,229 stream miles in 

Massachusetts (Commonwealth of Massachusetts, 

1998), using USEPA recommended distances of 5 to 10 

mi per site for wadeable streams and 25 mi per site for 

larger streams (U.S. Environmental Protection Agency, 

1997a), and an estimated ratio of 6:1 for small to large 

streams (where small streams are first, second, and 

third order and large streams are fourth and fifth order; 

this estimate is derived from the Neponset Basin analysis, described below), would require 754 to 1,560 sampling sites at a minimum. These values are likely to be 

underestimates of the number of sites required to characterize the spatial variability in water-quality 

conditions in Massachusetts streams, given the heterogeneous land uses, relatively short length of streams 

between tributaries, and frequency of point sources and 

dams in the State. These factors are potentially significant influences on water quality and decrease the 

length of stream of which a sampling site could be 

representative. Similarly, there are several thousand 

lakes in Massachusetts (Robert Hartzel, Massachusetts 

Department of Environmental Management, written 

commun., 1993), all of which would need to be 

sampled in an exhaustive approach. Moreover, these 

stream and lakes sites would need to be sampled 

repeatedly for some water-quality conditions. One 

potentially feasible approach for an exhaustive monitoring program within realistic resource limitations 

might be to use remote-sensing techniques; an example 

would be the use of remote-sensing data to provide 

reconnaissance-level information on the trophic state of 

lakes (Waldron and others, 2001). However, assessments conducted through such methods would be considered less rigorous than those based on direct 

sampling. 

Monitoring also may be defined by the waterquality indicators or parameters measured (fig. 1). In 

physical and chemical monitoring, parameters such as 

flow, temperature, pH, dissolved oxygen, turbidity, 

and chemical concentrations in the water column and 

sediment are measured. Biological monitoring 

(biomonitoring) can include the identification a

meration of macroinvertebrates, fish communiti

macrophytes (aquatic plants) and measurement

fish-tissue-contaminant, algae, or chlorophyll-a 

concentrations. Physical and chemical paramete

also are considered exposure indicators, in that 

depict the level of exposure for aquatic life (or h

to stressors, whereas biomonitoring indicators, 

response indicators, depict the response of the b

cal community to the physical and chemical str

(C.O. Yoder, Ohio Environmental Protection Ag

written commun., 1997). Advantages to physica

chemical monitoring are that the measurements 

ples are relatively simple to make or collect, an

results generally are unambiguous and quantitat

the other hand, these parameters are spatially an

temporally variable, potentially numerous, and 

costly to analyze. Routinely analyzing for all po

stressors in a monitoring network, especially w

organic compounds and metals are included, ca

prohibitively expensive. Biomonitoring indicato

advantageous in that they directly assess biolog

integrity and may be more valid measures of im

ment for aquatic life uses than the status of wat

relative to numerical water-quality standards (C

Yoder, written commun., 1997; U.S. Environme

Protection Agency, 1999). Biomonitoring indic

such as macroinvertebrate assessments also inte

the effects of stressors over time, thereby more 

rately representing water-quality conditions tha

highly variable than repeated point measuremen

physical or chemical indicators; they also can re

the effects of unknown stressors. However, alth

biomonitoring indicators may more readily dete

impairments, they generally cannot provide info

tion to indicate the causes or sources of the imp

ments. Moreover, biomonitoring approaches are 

appropriate for assessing the status of waters fo

involving human health. Finally, different speci

skills may be needed to conduct biomonitoring 

ments than those needed to sample for physical 

chemical parameters. 

Other categories or types of monitoring a

based on the type of water resource being moni

and the uses of the monitoring results (fig. 1). M

ing approaches for streams, lakes, ground-wate

other water-resource types must suit the tempor

spatial variability that results from the unique h

logic regime of the water resource. Logistical a
Design Considerations for a Statewide Monitoring Ne

of sampling the various water-resource types also must 

be considered. For example, daily or more frequent 

sampling may be needed to characterize water-quality 

in some streams, especially during storm events, 

whereas weekly sampling may be adequate for lakes, 

and monthly or less frequent sampling would be sufficient to characterize ground-water quality. The 

intended use of the information also affects the dataquality objectives of the program, as well as other 

aspects of the monitoring approach design, including 

the frequency, location, and types of measurements 

collected.

This review of monitoring approaches reemphasizes the importance of a clear definition of goals 

and objectives before monitoring programs can be 

designed. Multiple approaches may be needed in a 

monitoring program to meet conflicting requirements 

of the identified water-quality information needs. 

Finally, knowledge of the hydrologic and water-quality 

system, including the physical, chemical, and biological processes affecting the sources, transport, and 

attenuation of contaminants of concern, also is essential in developing the monitoring approaches that will 

meet the program’s objectives. 

Ongoing Monitoring Activities by 

State Agencies in Massachusetts

To determine the extent of water-quality 

monitoring activities in the Commonwealth of 

Massachusetts, the USGS, on two occasions, contacted 

State agencies and their constituent divisions, offices, 

bureaus, and programs. In 1998, a written questionnaire was distributed and, in 2000, telephone calls were 

made to supplement and update the responses to the 

1998 questionnaire. Massachusetts agencies contacted 

included the DEP, DEM, DFWELE, Massachusetts 

Coastal Zone Management (MCZM), MWRA, 

Metropolitan District Commission (MDC), Department of Public Health, Massachusetts Highway 

Department (MHD), Cape Cod Commission, and 

Massachusetts Waterwatch Partnership. This section 

reports on ongoing water-quality-monitoring activities 

in the State as determined from these contacts (table 1) 

and briefly discusses how these activities might be used 

in a comprehensive statewide water-quality monitoring 

strategy.

The DEP/DWM is responsible for coordi

of water-quality and quantity monitoring and re

tion in the State's major watersheds. Through th

MWI, the DEP now assesses water quality on a 

rotating basis in the 27 major watershed units a

Massachusetts on a 5-year cycle, with approxim

5 watershed-unit water-quality assessments taki

place each year. The assessments are multi-purp

nature, with physical, chemical and biological w

quality being evaluated primarily to determine i

water bodies or portions of them meet water-qu

standards and their designated uses. Typical mon

program elements currently include lake sampli

for TMDL development, fish-toxics monitoring

benthic macroinvertebrate measurements, and s

or issue-specific water-quality sampling especia

for CWA purposes (A.S. Johnson, Massachuset

Department of Environmental Protection, Divis

Watershed Management, written commun., 199

Much of the monitoring occurs in MWI basins 

in the research year (Year 2) of the 5-year cycle

site ambient monitoring is not conducted statew

although a pilot program is underway in the Ce

Region (A.S. Johnson, Massachusetts Departme

Environmental Protection, Division of Watershe

Management, written commun., 1999).

Several agencies in addition to the DEP/D

including MWRA, MDC, MHD or their subdiv

and DFWELE, support routine, environmental 

quality monitoring (table 1). Others monitor for 

pliance with specific regulations, such as monito

DEP's Drinking Water Program for public-water 

compliance with drinking-water-quality regulat

Some agencies support water-quality studies th

the administration of special programs and gran

relatively short-term studies; these agencies inc

the MCZM and the Lakes and Ponds Program o

DEM. The MCZM’s Marine Monitoring and Re

Program assesses wetlands and studies the effec

contaminated sediment, for example. The DEM 

and Ponds Program performs studies of water-q

problems related to occasional low flushing rate

lakes in some state parks.

The MDC through its Watershed Manage

Division collects a great deal of environmental 

in its extensive fixed-site network in the Quabb

Reservoir, Ware River, and Wachusett Reservoi

watersheds. This network monitors drinking-wa

sources used by much of the metropolitan Bost

area. Samples are collected from many tributary 

streams and the reservoirs at frequencies that va

depending on the water-quality constituent mon
ewide Water-Quality Network for Massachusetts

Agency Program

Description

and focus of 

monitoring program

Sampling 

parameters

Type of 

sampling site

Duration of 

sampling 

Geographic area 

of activity

Cape Cod Commission Water Resources Office Site-specific assessment 

projects

Vary by project Vary by project Short term Cape Cod

Coastal Zone Management Coastal Water Quality/ 

Coastal Nonpoint 

Pollution Control

-- -- -- -- --

Coastal Water Quality/ 

Massachusetts Bays

Wetlands health Dissolved oxygen, pH, 

nutrients, salinity, 

macroinvertebrates, 

vegetation, birds

Fixed Short term Coastal areas

Marine Monitoring and 

Research

Wetlands assessments; 

contaminated sediments

Water chemistry, 

macroinvertebrates, 

vegetation, birds

Variable Short term Coastal areas

Department of Environmental 

Management 

Forests and Parks No ongoing monitoring 

program

-- -- -- --

Natural Resources /Areas 

of Critical 

Environmental Concern

No ongoing monitoring 

program

-- -- -- --

Water Resources / Data 

Collection and Analysis

Cooperative programs with 

USGS

Vary by program Fixed and 

variable

Short and 

long term

Varies by 

program

Water Resources / Lakes 

and Ponds

Lakes and ponds in some 

State parks

Vary by issue Variable Short term Statewide

Engineering / Waterways No ongoing monitoring 

program

-- -- -- --

Department of Environmental 

Protection

Resource Protection / 

Drinking Water

Compliance of public-water 

suppliers with drinkingwater regulations

Drinking-water 

contaminants

Fixed Long term Statewide

Resource Protection / 

Watershed Management

Clean Water Act monitoring 

and assessment; 

Massachusetts Watershed 

Initiative (MWI) 

monitoring

Water chemistry; benthic 

macroinvertebrates; 

lake vegetation; fish 

toxics; others

Variable Short term Statewide, but 

focused in 

MWI Year 2 

basins
Design Considerations for a Statewide Monitoring Network 11

Resource Protection / 

Wetlands and 

Waterways

No ongoing monitoring 

program

-- -- -- --

Department of Fisheries, 

Wildlife, and Environmental 

Law Enforcement

Fisheries and Wildlife Fish community surveys in 

MWI watersheds; special 

studies related to game 

fish population

Fish community -- -- --

Marine Fisheries Fish and shellfish health Dissolved oxygen, 

temperature, bacteria

Fixed Long term Coastal areas

Department of Public Health Environmental Health 

Assessment

No ongoing monitoring 

program 

-- -- -- --

Massachusetts Highway 

Department

Research and Materials Highway runoff and publicwater suppliesRoad-salt constituents Fixed Variable Statewide

Metropolitan District 

Commission

Watershed Management / 

cooperatively with 

Massachusetts Water 

Resources Authority

Drinking-water protection Nutrients, alkalinity, 

hardness, bacteria and 

other pathogens, and 

macroinvertebrates

Fixed Long term Quabbin 

Reservoir, 

Ware River, 

and Wachusett 

Reservoir 

watersheds

Watershed Management Public-beach monitoring Bacteria Fixed Long term, 

summer

Public beaches

Massachusetts Water 

Resources Authority

Water quality in Boston 

Harbor and tributaries

Sewage contaminants 

(nutrients, bacteria, 

others)

Fixed Long term Boston Harbor 

and 

tributaries; 

beaches

Agency Programand focus of 

monitoring program

Sampling 

parameters

Type of 

sampling site

Duration of 

sampling 

Geographic area 

of activity
12 Statewide Water-Quality Network for Massachusetts

Sampling frequency ranges from daily for Quabbin 

Reservoir (although samples are sometimes collected 

twice daily at the outlet to the aqueduct), to biweekly at 

tributary sites. Sampling parameters are primarily 

indicator bacteria and nutrients (nitrogen and phosphorus species). Monthly reservoir depth profiles for temperature, pH, dissolved oxygen, and specific 

conductance also are made in Quabbin Reservoir from 

April through November. In the Wachusett watershed, 

indicator bacteria samples are collected generally daily 

in the reservoir and weekly in tributaries; nutrients are 

sampled weekly in tributaries; and reservoir profiles are 

conducted monthly. Field parameters of temperature, 

dissolved oxygen, pH, and specific conductance are 

measured at the time of sample collection. Sampling 

also is conducted for Giardia, Cryptosporidium, phytoplankton in Quabbin and Wachusett watersheds and, 

on occasion in Quabbin, includes a number of other 

water-quality constituents, such as iron, color, turbidity, and total suspended solids. In addition to the waterchemistry and bacteria monitoring, an MDC biomonitoring program conducts macroinvertebrate sampling at 

about 12 to 24 fixed sites in tributary streams. The macroinvertebrate data are used as integrated measures of 

stream quality and changes in quality over time. 

The MWRA monitors water quality in Boston 

Harbor and its tributaries. In addition, MDC’s Watershed Management Division, working for the MWRA, 

monitors for potential beach contamination by bacteria 

in summer that may cause the beaches to be closed. 

Monitored areas include the Charles, Neponset, and 

Mystic Rivers, Dorchester Bay, and the Inner Harbor. 

Water-quality conditions in these areas are determined 

by regular sampling and measurements of algae, suspended solids, turbidity, dissolved oxygen, and nutrients. The health of fish, shellfish, and other harbor 

animal communities also is routinely monitored. 

The stream water-quality data collected by MDC 

and MWRA include many of the sampling parameters 

needed to assess compliance with State water-quality 

standards. Thus, these data would be useful in determining use-support of the sampled stream reaches. 

However, the spatial distribution of sampling sites is 

limited, and the targeted site-selection approach 

would make it difficult to extrapolate monitoring 

results to unsampled streams (see below for further 

discussion) The MDC and MWRA data, particularly 

from sites in the relatively pristine Quabbin watershed, 

however, could be used to characterize background or 

unimpaired conditions in Massachusetts streams. 

The MHD collects water-quality samples 

rily from ground water from municipal and priv

water supplies statewide. This monitoring focus

on contamination associated with road-salt cons

of highway runoff, such as sodium, calcium, an

chloride. Although this network might overlap w

some fixed sites in a proposed surface-water-qu

monitoring network, the limited range of water-

constituents indicates that this program would p

only ancillary data for other monitoring objecti

The DFWELE/DMF monitoring program 

collects environmental data at some 350 sites in 

the coastal waters of Massachusetts. Primary da

collection efforts focus on bacterial contaminat

shellfishing beds. These data have been used for 

ing designated uses of coastal waters for the Sta

305(b) report and will continue to be very usefu

this purpose. The distribution of sampling sites i

to be based on a targeted approach, however, su

additional data or alternative approaches would 

needed to develop a comprehensive assessment 

ignated use of all coastal waters as defined by 3

purposes. The DFWELE/DFW conducts fish co

nity surveys throughout the State, following the 

basin cycles, and monitors game fish population

Quabbin and Wachusett watersheds. These data 

use determinations for aquatic life in sampled s

but would be difficult to extrapolate to unsampl

streams.

In addition to the State agencies with resp

bilities for monitoring water quality, there are a

100 local volunteer groups that are concerned w

some aspect of water quality. These groups, ma

of which are associated with the Massachusetts 

Waterwatch Partnership, generally are distribute

throughout the State and may focus their efforts 

streams, lakes or ponds, and coastal habitats. Th

activities may range from lobbying to occasiona

toring to maintaining a full-time professional st

such as that of the Charles River Watershed Ass

tion. These volunteers can serve as an important 

a statewide water-quality-monitoring network, b

lecting reconnaissance or higher-level data, by 

ing information on local impairments and pollu

sources, and by otherwise supplementing agenc

grams. Many of these groups are active particip

the MWI basin teams. Volunteer monitoring pro

in Massachusetts are summarized in a recent re

EOEA by River Network (Dates and others, 20
Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assess

TIER I: BASIN-BASED MONITORING 

PROGRAM FOR THE CLEAN WATER 

ACT STATEWIDE ASSESSMENT

Tier I Monitoring Program 

Objectives and Approaches

The objective of Tier I of the statewide monitoring program is to provide a periodic assessment of the 

quality of the State’s surface and ground waters, as is 

required by Section 305(b) of the CWA. The waterquality questions posed by this objective are: (1) what 

fraction of the State’s streams, lakes, ground waters 

and marine waters support their designated uses, and 

(2) what are the causes (pollutants or other stressors; 

U.S. Environmental Protection Agency, 1997a) and 

sources of impairments, where designated uses are not 

met. The designated uses for these water body types are 

defined by the State as primary contact recreation 

(swimming), secondary contact recreation (boating and 

fishing), aquatic life support, fish consumption, shellfishing, aesthetics, and drinking water. As stated previously, shellfishing and drinking-water uses and the 

quality of marine waters and ground waters, which are 

monitored by agencies other than DEP/DWM, are outside of the scope of the monitoring program described 

in this report. 

Massachusetts Surface-Water Quality Standards 

(MGL Ch. 21, section 27; 314 CMR 4.00, 1995) provide criteria by which to determine whether water 

bodies meet their designated uses. The criteria are 

established in terms of water classes that encompass 

several uses, but also can be grouped according to the 

individual designated uses (Kennedy and others, 1995; 

Commonwealth of Massachusetts, 1997, 1998; A.S. 

Johnson, Massachusetts Department of Environmental 

Protection, written commun., 2000). The standards 

are primarily numeric criteria, such as maximum or 

minimum acceptable values for pH, temperature, or 

dissolved oxygen, and can be used to directly define 

sampling parameters for the monitoring program 

(table 2). Assessments of use support also include 

the interpretation of narrative standards, which 

requires different types of information. For example, 

the occurrence of nutrient concentrations that 

encourage cultural eutrophication may be assessed 

with macrophyte mapping; or macroinvertebrat

community indices as well as pH and dissolved-

concentrations may be used to determine wheth

native and diverse aquatic community exists, w

the definition of the aquatic life use (MGL, Ch. 

section 27 and CMR 4.02, 1995; A.S. Johnson, 

Massachusetts Department of Environmental 

Protection, written commun., 1999). 

Requirements for a Tier I monitoring pro

are that it be statewide in scale, comprehensive 

water bodies in the Commonwealth are assesse

repeated at regular intervals. The need for comp

sive spatial coverage indicates that synoptic-sur

rather than fixed-station monitoring, approache

appropriate, and that “snapshots” of existing co

tions, rather than trend data, are needed. Howev

short-term temporal variability in water-quality 

conditions must be measured adequately to dete

whether the state numeric water-quality standar

met. The proposed monitoring program also sho

lead to improvements in the 305(b) assessment, 

increasing the number of stream miles and lake 

assessed as compared to previous years and red

the historical bias towards streams and lakes wi

known water-quality problems. The requiremen

comprehensive (“100 percent”) monitoring of a

water bodies also means that a probabilistic app

which provides inferential information on all w

bodies by sampling a relatively small number o

will be needed. In addition, information is need

causes of impairment and the sources of impair

stressors, as well as on the use-support status of 

water bodies, both for the 305(b) assessment an

the basin-based assessments of the MWI teams

water-quality data are needed at a scale that is s

ciently dense so that existing conditions can be 

to land uses and other causes and sources of spe

impairments. Finally, Massachusetts’ commitm

the watershed-based, rotating-basin approach to 

resource assessment and management requires 

monitoring design for the 305(b) assessment, lik

components of a comprehensive statewide mon

strategy, be integrated with the MWI. Thus, the 

toring program must be designed to be impleme

a 5-year, rotating-basin cycle and should otherw

supplement the missions of the MWI teams.
ewide Water-Quality Network for Massachusetts

Table 2. Selected surface-water quality standards and criteria for determining use-support status in Massachusetts streams—Continued

Sampling

parameter Water-quality standards

Criteria for determining use-support status

Supporting Partially supporting Not supporting

Aquatic-Life Use

Water chemistry

Dissolved oxygen ...................... Cold water:

> 6.0 mg/L and > 75% saturation unless 

background is lower

Warm water:

> 5.0 mg/ and > 60% saturation unless 

background is lower

Standards met in > 90% of 

measurements

Standards not met in 11 to 

25% of measurements

Standards not met in >25% 

of measurements

pH (standard units) .................... 6.5 to 8.3 and change < 0.5 outside

of background range

Standards met in > 90% of 

measurements

Standards not met in 11 to 

25% of measurements

Standards not met in >25% 

of measurements

Temperature1..................................... Cold water:

<68 ̊F and change <3 ̊F due to a discharge

Warm water:

<83 ̊F and change <3 ̊F in lakes and <5 ̊F in rivers 

due to a discharge

Standards met in > 90% of 

measurements

Standards not met in 11 to 

25% of measurements

Standards not met in >25% 

of measurements

Turbidity .................................... Narrative standard Change < 5 turbidity units 

due to a discharge

BPJ BPJ

Suspended solids ....................... Narrative standard < 25 mg/L and change <10 

mg/L due to a discharge

BPJ BPJ

Nutrients .................................... Narrative standard: Nutrients shall not exceed the 

site-specific limits necessary to control 

accelerated cultural eutrophication

Site-specific criteria; 

maintain balanced 

biocommunity; 

no pH or dissolved oxygen 

violations

BPJ BPJ

Toxic pollutants ......................... Ammonia <0.254 mg/L as NH3-N2

Chlorine <0.011 mg/L TRC

Standards met BPJ Standards are exceeded in 

>10% of samples

Sediment chemistry and toxicity

Ontario guidelines for L-EL and S-EL

Toxic pollutants ......................... -- <L-EL One pollutant between 

L-EL and S-EL

One pollutant >S-EL

GM, geometric mean; LEL, lowesteffect level, or concentration of a contaminant where no adverse effects would be expected; SEL, severeeffect level, or concentration of a contaminant where severe 

detrimental effects would be expected; L-EL and S-EL values from Persaud and others, 1992; n, number of samples; PCBs, polychlorinated biphenyls; RBP, Rapid bioassessment protocol; TRC, total 

residual chlorine; μg/kg, microgram per kilogram; mg/L, milligrams per liter; mL, milliliter; ng TEQ/kg, nanogram dioxin toxic equivalents per kilogram; >, actual value is greater than or equal to value 

shown; < actual value is less than or equal to value shown; >, actual value is greater than value shown; <, actual value is less than value shown; %, percent;  ̊F, degrees Fahrenheit; --, no applicable 

standards]
Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assessment 15

Aquatic-Life Use—Continued

Ontario guidelines for L-EL and S-EL

Nutrients .................................... -- <L-EL Between L-EL and S-EL >S-EL

Toxicity...................................... -- >75% survival >50% and <75% survival <50% survival

Biology

Macroinvertebrates .................... -- Non-impaired based on 

RBP II or III

Slightly impaired based on 

RBP II or III

Moderately or severely 

impaired based on RBP 

II or III

Fish community......................... -- BPJ BPJ BPJ

Habitat and flow ........................ -- BPJ BPJ Dewatered streambed due 

to artificial regulation or 

channel alteration

Macrophytes .............................. -- BPJ Non-native plant species 

present, but not 

dominant, BPJ

Non-native plant species 

dominant, BPJ

Plankton/Periphyton .................. -- No algal blooms Occasional algal blooms Persistent algal blooms

Tissue chemistry

PCBs in whole fish .................... -- <500 μg/kg wet weight BPJ BPJ

PCBs in aquatic tissue ............... -- <0.79 ng TEQ/kg wet 

weight

BPJ BPJ

DDT in aquatic tissue................ -- <500 μg/kg wet weight BPJ BPJ

Primary Contact Recreation Use

Dry-weather guidance: Maximum of <400 colonies/100 mL for n<5

Wet-weather guidance: <2,000 colonies/100 mL

Fecal coliform bacteria............. GM of <200 colonies/100 mL in any 

representative set of samples and <10% of 

samples >400 colonies/100 mL

Standards met in >90% of 

measurements for all 

samples or dry- and wetweather guidances met 

Standards exceeded in 11 to 

25% of samples or dryweather guidance met 

and wet-weather 

guidance not met

Standards exceeded in 

>25% of samples 

pH .............................................. Same as for aquatic life Standards exceeded in 

<10% of measurements

Standards exceeded in 11 to 

25% of measurements

Standards exceeded in 

>25% of measurements

pg

parameter Water-quality standards

Supporting Partially supporting Not supporting
ewide Water-Quality Network for Massachusetts

1 Maximum daily mean temperature in one month, from at least 6 measurements evenly distributed over 24 hours.

2 Ammonia concentration varies with pH; value shown is for pH equal to 9.0.

Primary Contact Recreation Use—Continued

Temperature............................... Same as for aquatic life Standards met Standards exceeded in 11 to 

25% of measurements

Standards exceeded in 

>25% of measurements

Color and turbidity .................... Narrative standard Change < 5 turbidity units 

due to a discharge

Criterion for support 

exceeded in 11 to 25% of 

measurements

Criterion for support 

exceeded in >25% of 

measurements

Secchi disk depth....................... Narrative standard >4 feet Infrequent excursions from 

the criterion for support

Frequent and(or) prolonged 

excursions from the 

criterion for support

Aesthetics—Biocommunity ...... Narrative standard For lakes, macrophyte 

cover is <50% at 

maximum extent of 

growth

For lakes, macrophyte 

cover is 50 to 75% of 

lake area at maximum 

extent of growth

For lakes, macrophtye 

cover is >75% of lake 

area at maximum extent 

of growth

Secondary Contact Recreation Use

Dry-weather guidance: Maximum of <2,000 colonies/100 mL for n<5 or GM of 

<1,000 colonies/100 mL for n>5 and <10% of samples >2,000 colonies/100 mL

Wet-weather guidance: <4,000 colonies/100 mL

Fecal coliform bacteria............ GM of <1,000 colonies/100 mL in any 

representative set of samples and <10% of 

samples >2,000 colonies/100 mL

Dry- and wet-weather 

guidances met

Dry-weather guidance met 

and wet-weather 

guidance not met

Dry-weather samples 

guidance not met

Aesthetics—Biocommunity ...... Same as for primary contact recreation Same as primary contact 

recreation

Same as primary contact 

recreation

Same as primary contact 

recreation

Aesthetics Use

Aesthetics—Visual

observation ............................ No objectionable bottom deposits, floating debris, 

scum, or nuisances; 

No objectionable odor, color, taste, or turbidity, or 

nuisance aquatic life

Criteria met Objectionable conditions 

neither frequent or 

prolonged, BPJ

Objectionable conditions 

frequent and(or) 

prolonged, BPJ

Fish Consumption Use

DPH Fish Consumption 

Advisory List......................... -- Not applicable, precluded 

by statewide advisory for 

mercury

Not applicable Water body is on DPH Fish 

Consumption Advisory 

List

pg

parameter Water-quality standards

Supporting Partially supporting Not supporting
Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assess

Tier I Monitoring Design for the 

Neponset River Basin

A monitoring design for Tier I of the statewide 

program was developed using the Neponset River 

Basin in Eastern Massachusetts as an example. The 

Neponset basin was used as a pilot for the 

Massachusetts Watershed Initiative (MWI) in the early 

1990s (Kennedy and others, 1995). It was chosen as the 

study area for the current effort to take advantage of the 

extensive data collected in the MWI pilot and to compare the MWI pilot approach to that of the monitoring 

network proposed here. The Neponset Basin is a 117-

square-mile watershed that is drained by the Neponset 

River to Dorchester Bay (Boston Harbor) in Quincy, 

Mass. (fig. 2). It is divided into 14 tributary subbasins, 

which are inventory, planning, and communityorganizational units (fig. 2; Warren Kimball, Massachusetts Department of Environmental Protection, oral 

commun., 1998; Russell Cohen, Massachusetts Department of Fisheries, Wildlife, and Environmental 

Enforcement, oral commun., 1999). Land use within 

the basin is 19 percent urban, 35 percent residential, 

and 48 percent forest cover and other undeveloped land 

(including 2 percent agricultural land use). 

Definition of Water 

Resources in the Basin

Data Sources

The first step in a comprehensive assessment of 

water resources in an area is to inventory the water 

resources, that is, to define the population of water 

bodies to be assessed (Gilbert, 1987). Streams and 

lakes in the Neponset Basin were inventoried using 

centerline hydrographic data at 1:25,000-scale 

developed by Massachusetts Office of Information 

and Environmental Information (MassGIS) of the 

Executive Office of Environmental Affairs (EOEA) and 

the USGS (fig. 2). Hydrography at the 1:25,000-scale 

corresponds to streams, lakes and ponds, and other 

water resources represented on the 7.5- by 15-minute 

USGS topographic quadrangles. The MassGIS centerline data, originally derived from the quadrangle 

hydrography, are the standard digital data used by 

MWI teams and other state agencies for surface-water 

mapping, planning, analysis, and management at the 

major-basin and larger scales; the MassGIS data also 

are increasingly used by municipalities and loca

nizations for these purposes. The MassGIS 1:25

digital hydrography is directly linked to DEP’s 

and PALIS inventory systems (Halliwell and ot

1982; Ackerman and others, 1984; Ackerman, 1

for streams and lakes, respectively. The MassG

are not currently linked to the USEPA river reac

set (RF3 or the National Hydrography Dataset, 

that USEPA is recommending for mapping and 

sis of 305(b) assessment data (U.S. Environmen

Protection Agency, 1997a, 1997c). The NHD, ho

is at a scale of 1:100,000; which does not provi

resolution needed by the MWI teams and DEP/

for water-quality monitoring, assessment, or ma

ment decisions within the 27 individual major b

Massachusetts; it also was not available at the t

this analysis. It should be noted that the MassG

1:25,000 data could be readily linked to the US

river reach data, when a final version of that dat

available.

Streams

Streams are linear features that theoretica

can be assessed at an infinite number of point lo

along the stream network. In practice, streams m

inventoried in terms of length (stream miles) an

in terms of sections or reaches that are defined b

physical boundaries, such as confluences with o

streams or watershed boundaries. The DEP’s SA

system, which identifies named streams of vary

length that are classified by major basin (Halliw

others, 1982), is an example of an inventory bas

stream reaches. The approach used here for inv

ing streams in the Neponset Basin is guided by 

need for a conceptual definition of lengths of st

within which the water-quality conditions of int

are expected to be uniform; this is a general nee

of most stream water-quality assessments, wher

conditions in stream reaches must be determine

by extrapolating point sampling data. Lengths o

streams with uniform water quality depend on i

outputs, and instream transformation or attenua

processes, which vary by contaminant. Thus, it 

possible to define in advance a length of stream 

which one sample would be representative for a

contaminants under all circumstances of hydrol

conditions and land use or other contamination 
18 Statewide Water-Quality Network for Massachusetts

42o05'

42o

10'

71o

15'

71o10'

71o

05'

42o

15'

EXPLANATION

STUDY AREA

LAKES

BASIN BOUNDARY

TRIBUTARY SUBBASIN 

 BOUNDARY

PERENNIAL STREAMS

INTERMITTENT STREA

CAPE COD 

BAY

0 5 MILES

0 5 KILOMETERS

Neponset River School Meadow Brook

Mill Br ook

Germa ny Brook

Mill Brook

Neponset River

Beaver Brook

Tra phole Brook

Meadow

East Branch

Neponset

Beaver Meadow

Bro ok

Pequid Brook

Steep Hill Brook

Ma ssapoag Brook

Ponkapo a g Brook

Ne ponset Riv er

Purga tory

Brook

Mother Broo k

Neponset River

Pine Brook

Unquity

Brook

Brook

0 50 MILES

0 50 KILOMETERS

73 ̊00'

42 ̊30'

42 ̊00'

41 ̊30'

72 ̊00'

71 ̊00'

70 ̊00' Massachusetts

Bay

Nantucket

Sound

ATLANTIC OCEAN

Figure 2. The Neponset Basin in eastern Massachusetts.
Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assess

USEPA guidelines address this issue by stating that “a 

monitoring station can be considered representative of 

a stream water body for a distance upstream and downstream that has no significant influences that might tend 

to change water quality or habitat quality;” such influences are listed as point or non-point sources to a 

stream or tributary, changes in land use or other watershed characteristics, changes in streambank characteristics, large tributaries, or hydrologic features such as 

dams (U.S. Environmental Protection Agency, 1997a, 

p. 2-1).

Streams in the Neponset Basin were inventoried 

for the network design using a systematic, relatively 

unbiased approach to defining stream lengths expected 

to have relatively uniform water quality that could be 

represented by a single sample. Thus, stream reaches 

were delineated using confluences with tributaries, 

significant lakes, and point-source discharges. These 

features correspond to potential inputs, outputs, or 

transformations of stream-water contaminants in a 

stream reach. A confluence with a tributary potentially 

changes water quality in a stream when the tributary 

water carries contaminants, or contaminants in the 

stream are diluted through the addition of cleaner tributary water. Transport through lakes potentially changes 

water quality through changes in flow, such that particulates and associated contaminants (for example, 

metals) may settle, or through transformation of biologically active contaminants such as nutrients. Flow 

through stream reaches bordered by extensive wetlands 

also may have these effects; however, wetlands were 

not used to delineate stream segments because of the 

indeterminate effects wetlands have on water quality 

and because detailed spatial data for wetlands were not 

available. Point-source discharges may alter streamwater quality through direct input of contaminants or 

through changes in the physical properties (temperature, pH) of the stream water. The physical characteristics of tributary confluences, lakes, and point-source 

discharges can be consistently determined for any 

basin, are generally applicable for many contaminants, 

and do not require relatively subjective judgments 

(such as judgments about the effects of land use on 

water quality). 

Permitted discharges under the NPDES 

program were used to represent significant pointsource discharges to the streams in the basin, for the 

purposes of defining stream segments. Information 

on NPDES dischargers was obtained from the Permit 

Compliance System of USEPA Region I (N. Mason, 

U.S. Environmental Protection Agency, Boston

Mass., written commun., July and August, 1998

U.S. Environmental Protection Agency, 1998a) 

from the 1994 DEP assessment of the basin (Ke

and others, 1995). A digital data layer of NPDE

charger locations was obtained from DEP (Bria

Brodeur, Massachusetts Department of Environ

Protection, 1998). This information was review

identify discharges with the potential for measu

effects on stream-water quality, based on inform

provided in the discharge permits (table 3). 

Stream segments were delineated in ARC

as described in the appendix. Only streams cod

perennial in the MassGIS data layer were inclu

(fig. 2). Streams were divided at confluences wi

perennial tributaries greater than 328 ft (100 m) 

length. Streams also were divided at inlets and 

of significant lakes (see “Lakes” section, below

further discussion) and at NPDES locations. Th

stream segmentation scheme is illustrated for a 

portion of the basin in figure 3 (note that stream

segment boundaries are at small distances up- a

downstream from confluences, lakes, and NPDE

as explained in the appendix). Stream order wa

mined for all perennial streams in the basin, and 

order was retained as an attribute of each stream 

ment. Stream order is a classification scheme th

be used as a surrogate for relative stream size; t

defined using the Strahler method (Gordon and 

1992). First-order streams are small streams at 

headwaters of drainages with no tributaries drai

them; second-order streams are formed by the j

of two first-order streams; third-order streams a

formed by the junction of two second-order stre

and so on (Gordon and others, 1992). Finally, w

shed areas were delineated for each stream segm

by using the MassGIS Watershed Analyst (Mas

2000b) as described in the appendix.

Summary statistics on number, length, str

order, and watershed area of perennial stream se

in the basin are presented in table 4. Three hund

twelve stream segments were delineated, compr

total of 152.6 stream miles. About half of the se

(51 percent) and stream miles (47 percent) were 

order streams (fig. 4A). Watershed of first-order 

streams were nearly all less than one-half squar

in area. Twenty-seven percent of stream miles w

second-order, 18 percent were third order, 6 per

were fourth order, and 8 percent were fifth orde

distribution of stream segments was similar to t

stream miles (table 4). Second- and third-order 
20 Statewide Water-Quality Network for Massachusetts

included the major streams draining the 14 tributary 

subbasins as well as some smaller streams (fig. 4B–C). 

Fourth-order streams consisted primarily of the East 

Branch Neponset River and parts of the mainstem 

Neponset River upstream from the junction with the 

East Branch (fig. 4D). The only fifth-order stream in 

the basin was the mainstem of the Neponset River 

downstream from the East Branch (fig. 4E). 

Most (83 percent) stream segments were delineated based on confluences with tributaries, the most 

important factor in determining segment length. The 

average length of stream segments for all stream orders 

was about one-half mile, with median length for all but 

third-order streams about one-third mile. This level of 

segmentation is most appropriate for small (first- and 

second-order) streams, which commonly are represented by single segments. However, it is recognized 

that dividing larger (fourth- and fifth-order) streams at 

every tributary confluence probably results in m

stream segments than necessary to characterize 

quality conditions in these streams, because sm

tributaries flowing directly to large streams may 

have negligible effects on the larger streams’ qu

However, in urban areas, such as parts of the Lo

Neponset River, small tributaries may have disp

tionately large effects on water quality; these tr

ies, as culverted streams, may drain heavily dev

areas that are larger than the length or order of 

streams would suggest. The stream inventory pr

dures described here could be extended by usin

specific information to identify and retain small 

taries draining relatively large urban areas, whi

would be likely to affect water-quality in larger 

streams, and, conversely, to eliminate other sma

tributaries, not expected to have significant effe

Table 3. Discharges permitted under the National Pollutant Discharge Elimination System that were used in defining s

segments for Tier I monitoring in the Neponset Basin, Massachusetts

[Status of permit: Status as of December 1998. BOD-5, 5-day biological oxygen demand; TSS, total suspended solids; gal/d, gallons per day]

Facility name Type of 

discharge

Status of

permit Type of discharge

Perm

disc

vol

Bird Machine Company...................................................... major active stormwater and noncontact cooling water unknown

Hollingsworth and Vose ................................................ minor active strainer backwash and process water 700,000 g

Bird Roofing, Inc. ................................................................ minor active stormwater 40,000 ga

Plymouth Rubber Company................................................. major active stormwater and noncontact cooling water 2,600,000 

Foxboro Company ............................................................... minor active stormwater and noncontact cooling water 320,000 g

Factory Mutual Engineering ................................................ minor active runoff from equipment testing 15,000 ga

Harold E. Willis Treatment Plant......................................... minor unknown backwash from water-supply plant unknown

Senior Flexonics/ Metal Bellows Corporation..................... minor unknown unknown unknown

Effluent standard parameters Receiving wa

Bird Machine Company....................................................... temperature, pH, phosphorus, copper, lead, zinc, TSS, oil and 

grease

Upper Neponset River

Hollingsworth and Vose ....................................................... temperature, pH, dissolved oxygen, phosphorous, zinc, TSS, 

settleable solids, BOD-5, toxicity

Middle Neponset Rive

Bird Roofing, Inc. ................................................................ temperature, pH, TSS, oil and grease Middle Neponset Rive

Plymouth Rubber Company................................................. temperature, pH, copper, TSS, oil and grease East Branch Neponset 

Foxboro Company ............................................................... temperature, pH, fecal coliform bacteria, oil and grease, 

toxicity

Neponset Reservoir

Factory Mutual Engineering ................................................ temperature, pH, mercury, TSS, fecal coliform bacteria, oil 

and grease, toxicity

Neponset Reservoir

Harold E. Willis Treatment Plant......................................... unknown Mine Brook

Senior Flexonics/ Metal Bellows Corporation..................... unknown School Meadow Brook
Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assess

N

EXPLANATION

LAKES GREATER THAN 5 ACRES IN AREA

LAKES LESS THAN 5 ACRES IN AREA

PERENNIAL STREAM CENTERLINE

INTERMITTENT STREAM CENTERLINE

APPROXIMATE BOUNDARY OF STREAM SEGMENT—Segments defined by:

 Confluences with tributaries

 Significant lakes

 NPDES point discharges

0

0 0.5 MILE

0.5 KILOMETER

Figure 3. Criteria for segmenting stream hydrography for Tier I monitoring in the Neponset Basin, Massachusett
22 Statewide Water-Quality Network for Massachusetts

Lakes

Lakes in the Neponset Basin were inventoried 

for the network design by selecting all lakes and ponds 

represented in the 1:25,000-scale hydrography data 

layer that were larger than 5 acres, as described in the 

appendix (fig. 4F). The 5-acre threshold was selected 

in consultation with DEP/DWM as a criterion to define 

the significant lakes in a basin that should be included 

in a comprehensive, basin- or state-wide assessment. 

Lakes or lake polygons less than 5 acres (including 22 

lakes with PALIS codes) were numerous, but represented only 16 percent of the total lake acres in the 

basin. Additional lakes from the excluded subset could 

be added to the target population for the assessment as 

desired. The 46 lakes larger than 5 acres included 40 

named, PALIS-coded lakes and 6 unnamed lakes 

(table 5). Most were less than 35 acres and occurred on 

all except fifth-order streams. Five lakes, located on 

second- and third-order streams, were greater than 

200 acres.

Sampling Designs

For a comprehensive assessment of water 

resources in the Neponset Basin as required by 

305(b) of the CWA, water-quality information i

needed for all stream segments and lakes identi

the basin inventory. Theoretically, this informat

could be obtained by (1) directly sampling all s

segments and lakes (“exhaustive” approach), or 

(2) sampling a randomly selected subset of stre

segments and lakes and inferring conditions in 

rest of the population from the sampled subset (

bilistic” approach). In practice, an exhaustive ap

is almost never possible because of resource lim

tions. Although it is understood that its impleme

is not possible, the exhaustive approach was inv

gated at the request of DEP/DWM, along with o

approaches, to better define the issues and limit

relevant to sampling designs for a comprehensi

assessment. Finally, it should be noted that, alth

the spatial coverage of the exhaustive approach 

alistic, the discussion of the sampling paramete

frequency in this section is applicable to all the 

sampling approaches discussed for Tier I monit

Table 4. Summary statistics for stream miles and segments inventoried for Tier I monitoring in the Neponset Basin, 

Massachusetts

Stream order

Total

stream

miles

Stream segments

Number

Length, in miles

Average Median 25th 

percentile

7

per

First order ............................................ 72.2 158 0.46 0.31 0.15 0

Second order........................................ 31.6 58 .54 .32 .20 

Third order........................................... 28.1 47 .60 .52 .24 

Fourth order ......................................... 8.7 25 .35 .17 .12 

Fifth order............................................ 12.0 24 .50 .28 .19 

All stream orders ................................. 152.6 312 0.49 0.26 0.16 0

Stream segments

Number

Watershed area, in square miles

Average Median 25th 

percentile

7

per

First order ............................................ 72.2 158 0.37 0.19 0.05 0

Second order........................................ 31.6 58 1.53 1.05 .63 2

Third order........................................... 28.1 47 4.65 4.57 2.14 6

Fourth order ......................................... 8.7 25 28.1 25.8 22.3 37

Fifth order............................................ 12.0 24 86.3 88.7 77.4 91

All stream orders ................................. 152.6 312 9.55 0.72 0.15 4
Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assessment 23

42005'

42010'

71010'

42015'

71015'

42005'

42010'

71010'

42015'

71015'

42005'

42010'

71010'

42015'

71015'

42005'

71005'

42010'

71010'

42015'

71015'

42005'

71005'

42010'

71010'

42015'

71015'

42005'

71005'

42010'

71010'

42015'

71015'

D. FOURTH-ORDER STREAMS

F. LAKES

E. FIFTH-ORDER STREAMS

0 5 10 MILES

0 5 10 KILOMETERS

BASIN BOUNDARY

STRAHLER STREAM ORDER AS INDICATED

EXPLANATION

Figure 4. Perennial streams by stream order and lakes inventoried for Tier I monitoring in the Neponset River Basin, Massachusetts.
ewide Water-Quality Network for Massachusetts

Lake name Tributary basin ID PALIS-ID Lake-surface 

area, in acres

Strahler order 

of stream 

segment 

Watershed area

Acres Square miles

Avery School Pond........................................... Mother Brook 888 73001 6.44 1 -- --

Bird Pond ......................................................... Upper Neponset 416 73002 20.43 4 16,200 25.31

Blue Hills Pond/ Russell Pond......................... Pine Tree Brook 392 73003 8.94 3 970 1.52

Blue Hills Reservoir......................................... Pine Tree Brook 393 73004 12.17 1 62.3 0.10

Bolivar Pond (Ames Pond) .............................. East Branch Neponset 427 73005 19.79 4 6,380 9.97

Buckmaster Pond ............................................. Hawes Brook 396 73006 34.32 2 329 0.51

Clark Pond........................................................ Upper Neponset 440 73008 6.71 1 739 1.16

Cobbs Pond ...................................................... Upper Neponset 421 73009 14.25 3 1,168 1.82

Cranberry Bog Pond......................................... Upper Neponset 472 73011 8.12 0 78.4 0.12

Diamond Pond (Sawmill Pond) ....................... Upper Neponset 432 73012 7.98 1 1,285 2.01

East Dedham Pond........................................... Mother Brook 389 73016 7.89 1 1,002 1.57

Ellis Pond ......................................................... Hawes Brook 405 73018 17.05 3 4,883 7.63

Flynns Pond ..................................................... Mill/Mine Brook 409 73019 7.50 1 104 0.16

Forge Pond ....................................................... East Branch Neponset 476 73020 8.00 3 4,274 6.68

Ganawatte Farm Pond/ Pine Street Pond ......... Upper Neponset 455 73037 29.45 2 731 1.14

Glen Echo Lake (York Pond) ........................... East Branch Neponset 430 73022 15.75 1 58.6 0.09

Lymans Pond/Gay Street Pond ........................ Purgatory Brook 394 73021 25.13 1 144 0.22

Manns Pond...................................................... Massapoag Brook 450 73028 5.73 3 28,140 4.40

Massapoag Lake............................................... Massapoag Brook 454 73030 389.0 3 2,321 3.63

Mother Brook Pond.......................................... Mother Brook 388 73031 8.27 1 1,358 2.12

Muddy Pond..................................................... Steep Hill Brook 453 73033 19.77 1 261 0.41

Neponset Reservoir .......................................... Upper Neponset 471 73034 310.2 2 1,093 1.71

Neponset River Pond........................................ Neponset Estuary 367 73035 10.72 3 144 0.23

Pettee Pond....................................................... Hawes Brook 477 73036 9.53 2 2,360 3.69

Pinewood Lake................................................. Steep Hill Brook 447 73039 25.20 1 298 0.47
Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assessment 25

Plimpton Pond.................................................. Upper Neponset 418 73041 6.37 4 15,850 24.77

Ponkapoag Pond............................................... Ponkapoag Brook 397 73043 213.8 2 1,155 1.80

Popes Pond....................................................... Pine Tree Brook 385 73044 5.97 3 3,739 5.84

Railroad Pond................................................... Upper Neponset 434 73046 8.07 1 1,023 1.60

Reservoir Pond................................................. East Branch Neponset 408 73048 251.3 3 3,908 6.11

Sawmill Pond ................................................... Massapoag Brook 442 73049 5.89 2 16,190 2.53

Shephard Pond ................................................. Massapoag Brook 433 73068 5.58 3 6,439 10.06

South Trowel Shop Pond.................................. Massapoag Brook 444 73050 8.29 3 3,883 6.07

South Walpole Street Pond............................... Upper Neponset 473 73052 16.71 1 200 0.31

Sprague Pond ................................................... Middle Neponset 475 73053 7.44 99 71 0.11

Stoughton Pond/ Woods Pond.......................... Steep Hill Brook 452 73055 28.54 1 117 0.18

Town Pond ....................................................... Steep Hill Brook -- 73056 8.13 2 1,561 2.44

Turner Pond (Moreys Pond)............................. Mill/Mine Brook 429 73058 17.65 4 4,467 6.98

Turners Pond .................................................... Pine Tree Brook 25 73059 10.53 1 99.2 0.15

Unnamed lake .................................................. East Branch Neponset 423 none 10.79 4 17,470 27.30

Unnamed lake .................................................. Middle Neponset 470 none 7.38 0 31 0.05

Unnamed lake .................................................. Middle Neponset 412 none 8.67 1 53.7 0.08

Unnamed lake .................................................. Mill/Mine Brook 474 none 11.31 0 175 0.27

Unnamed lake .................................................. Upper Neponset 411 none 5.96 4 162,900 25.45

Unnamed lake .................................................. Upper Neponset 443 504 13.66 3 6,961 10.88

Willet Pond....................................................... Hawes Brook 404 73062 205.6 2 3,097 4.84

Lake name Tributary basin ID PALIS-ID Lake-surface 

area, in acres

Strahler order 

of stream 

segment 

Watershed area

Acres Square miles
26 Statewide Water-Quality Network for Massachusetts

Exhaustive Approach

Sampling Sites, Parameters, and Frequency

Sampling sites for the exhaustive approach 

corresponded to the 312 stream segments and 46 lakes 

identified in the Neponset Basin, or 357 potential 

sampling sites. However, it is expected that a basinspecific review of the stream-segment array would lead 

to a reduction in the number of stream segments on 

high-order streams; this is addressed further in the 

“Resource Requirements” section, below. Sampling 

parameters for the exhaustive approach also were 

selected to provide data to evaluate all numeric and 

narrative criteria in the State water-quality standards. 

The sampling parameters and frequency proposed for 

this approach are given in table 6. Differences in 

sampling parameters and frequency between lakes and 

streams are based on differences in physical, hydrologic, and ecological characteristics; sampling parameters and frequencies that vary by stream order are based 

on the assumption that stream order is a surrogate for 

stream size and flow characteristics. 

State water-quality standards require that 

dissolved-oxygen concentrations remain above a 

minimum concentration (unless decreased by natural 

causes) and that natural variations in concentration 

are maintained to support the aquatic life use (table 2). 

Temperature must be below a maximum value and 

must not vary by greater than specified values for 

cold- or warm-water fisheries. Dissolved-oxygen 

concentrations, pH, and temperature may vary seasonally and daily. In lakes, dissolved oxygen also varies by 

depth. Ideally, dissolved-oxygen concentrations and 

temperature would be measured continuously to determine use support, but this is well beyond the scope of a 

305(b)-type assessment. In addition, dissolved-oxygen 

measurements to depict “worst case” conditions should 

be made in the pre-dawn hours, when dissolved oxygen 

typically is at a minimum. It is proposed that field 

parameters of dissolved oxygen, temperature, and pH 

be measured repeatedly in streams from March to midOctober in conjunction with bacteria sampling (see 

below); specific conductance and turbidity also are 

proposed, as measures of general water quality and 

suspended solids, respectively. In lakes, measurements 

should be made at least once, during mid- to late summer, at multiple depths, but are proposed for spring 

and fall also in conjunction with other measurements. 

Ideally, dissolved oxygen, temperature, pH, and other 

field parameters (specific conductance) also could be 

measured every time a stream or lake is monito

because these field parameters are easy and inex

sive to measure and provide valuable informatio

water-quality conditions. 

Water-quality standards for fecal-coliform 

bacteria, an indicator of sewage contamination, 

maximum concentrations, as geometric means o

multiple samples, to support primary and secon

contact recreation uses. E. coli is another, comm

sampled fecal-indicator bacteria that future stan

could include. Bacteria concentrations in surfac

waters are variable and highly dependent on sto

water flows. For second- through fifth-order stre

is proposed that bacteria (fecal coliform and E. 

sampled monthly from March to mid-October (

samples, wet or dry weather), with collection o

five additional samples during this period target

at rainfall-runoff events (wet weather). For thes

purposes, wet-weather samples are generally de

as samples collected when streamflow is affecte

surface runoff, which varies among sites; as a p

matter, quantitative criteria to identify wet-weat

periods (for example, at least 0.5 in. of rain wit

2 days; Andrea Rex, Massachusetts Water Reso

Authority, oral commun., 2000) and dry-weathe

periods (for example, no rain for 3 days) probab

would be needed to direct the sampling program

first-order streams, where contact recreation is 

likely, monthly bacteria sampling (6 samples) i

posed during this period. It should be noted tha

even this frequent sampling for bacteria is not l

adequate for decisions on swimming safety at s

locations and times; rather, it is intended to dete

general conditions for the CWA.

Nutrients, nitrogen and phosphorus speci

contribute to eutrophication (excessive plant an

growth) in water bodies. Water-quality standard

nutrients are listed as “site-specific criteria to co

eutrophication” for aquatic life and recreational 

rather than as numerical criteria (table 2). Obvi

impairment of water bodies from eutrophication 

ally occurs during summer months, and is likely 

occur in lakes and larger, slower-moving stream 

reaches. Thus, it is proposed that sampling for n

occur about monthly from March to mid-Octob

third-, fourth-, and fifth-order streams with bact

sampling. Because nutrient concentrations vary 

input from stormwater flows, it might be necess

some of these samples be taken with the wet-w

bacteria samples. Tributaries contributing to lar
Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assess

lakes, where eutrophication may be of special concern, 

also could be sampled, regardless of the streamsegment order. Nutrient sampling is proposed once 

per assessment for lakes, in spring, as a general 

indicator of lake trophic status. Periphyton community 

analysis is a response variable for nutrients that integrates over time the effects of variable nutrient 

concentrations. Periphyton or phytoplankton analysis is 

proposed for larger order streams, once per assessment; 

phytoplankton analysis also could be considered for 

some or all lakes, but is not proposed for the current 

program.

Several parameters are proposed for sampling 

only once per assessment on high-order streams and 

lakes (table 6). High-order streams are more likely to 

receive and accumulate toxic chemicals, and thus are 

appropriate for toxicity testing of sediment for the 

aquatic life use. Sampling for chlorine and other specific toxics chemicals is not proposed (except for 

ammonia, which is sampled with nutrients), because 

the occurrence of these contaminants is dependent on 

specific types of point-source discharges. Sedimentchemistry is most appropriate in depositional areas in 

streams, that is, in impounded areas of high-order 

stream segments and behind dams. Thus, the number of 

sediment-chemistry sampling sites would be less than 

the total number of high-order stream segments and 

would be determined for each basin. Sediment chemistry in smaller streams could be assumed satisfactory 

unless information about specific point-discharges 

suggests otherwise. Streams that might support the 

fish consumption use also are appropriate for fish 

tissue sampling. For the purposes of this design, fish 

tissue sampling is proposed for third-, fourth-, and 

fifth-order streams but also could occur in some 

smaller streams. Detailed sampling parameters, in 

terms of fish species and contaminants, would be 

determined on a site-specific basis. 

Water-quality and public-health standards 

for suspended solids, turbidity, and transparency 

address aquatic life use, primary contact recreation, 

and aesthetics. Suspended solids is proposed for 

monthly and wet-weather measurement with bacteria 

sampling, because suspended solids vary with flow 

and may indicate sediment-borne contaminants; turbidity is included with field parameters. Secchi-disk 

transparency, an inexpensive measurement, could be 

measured in higher-order streams where appropriate 

with other field measurements. However, Secchi-disk 

depth can be highly variable, reflecting phytoplankton 

population dynamics. For lakes, where Secchi d

used as a primary indicator of trophic status, se

monthly measurement is proposed from mid-M

mid-October (table 6). Trophic status as indicat

Secchi disk can be used to assess the aquatic lif

Chlorophyll-a sampling and macrophyte 

measurements are proposed for lakes in additio

frequent Secchi-disk measurements. Chlorophy

concentration is another indicator of trophic sta

is proposed for semi-monthly sampling with Se

disk. Macrophyte mapping is proposed for lake

per assessment, in mid- to late summer. Macrop

cover would be used to assess the recreational u

well as the aquatic life use. 

Finally, benthic macroinvertebrates, subs

parameters, and other habitat measures provide 

grated assessment of water-quality conditions a

address narrative standards for aquatic life use. 

parameters referred to here are determined using 

Bioassessment Protocols (RBP II or III) as defi

DEP (Commonwealth of Massachusetts, 1997)

proposed that macroinvertebrates be monitored 

per assessment, during the critical period for th

logical communities, in all wadeable stream seg

Resource Requirements

In quantifying resource requirements, the 

sampling-site density along large streams was 

reduced, based on the assumption that further re

of the stream segmentation results would elimin

some segment boundaries along these streams, 

discussed previously. Sampling site density was 

reduced to one-half the number of stream segm

for fourth- and fifth-order streams (table 7), effe

yielding an average stream length per sample o

Fourth- and fifth-order streams in the Neponset 

Basin flow through wetland areas with many sm

tributaries, some of which would likely be iden

on further review as having a low potential to a

mainstem water quality; some segments also w

be eliminated from sampling because of access 

problems. Sampling-site density along third-ord

streams was reduced by one-third (table 7). Mo

order streams were segmented at substantial trib

however, some third-order streams also flow thr

wetlands and further review would likely elimin

some segment boundaries in these areas. Sampl

sites along first- and second-order streams were 

reduced, because in most cases a first- or secon

order stream is represented by only one segmen
28 Statewide Water-Quality Network for Massachusetts

1 Wadeable segments only 2 Sampling for transparency and macrophytes where appropriate

Table 6. Sampling parameters and frequency for an exhaustive approach to Tier I monitoring in the Neponset Basin, 

Massachusetts

[--, not sampled]

Water body

Sampling parameters 

Field

parameters 

Bacteria and 

suspended

solids

Nutrients Macroinvertebrates

Periphy

or 

phytopla

STREAMS --

First order............ monthly, March–

October

monthly, March–

October

-- once per assessment --

Second order ....... monthly, March–

October; plus 5 

wet weather

monthly, March–

October; plus 5 

wet weather

-- once per assessment --

Third order .......... monthly, March–

October plus 5 

wet weather

monthly, March–

October; plus 5 

wet weather

8 samples, 

March–October

once per assessment once per asse

Fourth order ........ monthly, March–

October plus 5 

wet weather

monthly, March–

October; plus 5 

wet weather

8 samples, 

March–October

once per assessment1 once per asse

Fifth order ........... monthly, March–

October plus 5 

wet weather

monthly, March–

October; plus 5 

wet weather

8 samples, 

March–October

once per assessment1 once per asse

LAKES .................. spring, midsummer, 

and fall

-- once per assessment, 

spring

-- --

Water body

Sampling parameters 

Sediment chemistry 

and toxicity

Fish

tissue Macrophytes Transparency Chlorop

STREAMS

First order............ -- -- -- -- --

Second order ....... -- -- -- -- --

Third order .......... once per assessment once per assessment -- -- --

Fourth order ........ once per assessment once per assessment once per assessment2 same as bacteria2 --

Fifth order ........... once per assessment once per assessment once per assessment2 same as bacteria2 --

LAKES .................. -- -- once per assessment;

midsummer

semi-monthly, 

March–October

semi-monthl

March–Oc
Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assess

These modifications, although arbitrary, were used to 

allow for a more realistic estimation of the resources 

required for an exhaustive sampling of water-resources 

in the basin. However, although yielding a more 

reasonable sampling density, the modifications 

also introduce subjectivity into the site-selection 

scheme and could be considered to compromise the 

exhaustive assessment.

Resource requirements for the exhaustive 

approach were defined in terms of the personnel 

needed for sample collection and of the laboratory 

analyses needed (table 7). The total number of 

sampling sites was 273 for streams and 46 for lakes, 

for a total of 2,423 site visits. Sampling sites fo

tissue, proposed for higher-order streams, was r

to a density of one sample per 2 mi of stream. P

nel requirements for sample collection were det

mined using estimates from DEP/DWM as follo

field parameters, bacteria, nutrients, and suspen

sediment (in streams), five sites per day for two 

macroinvertebrates, two sites per day for three p

plus one laboratory day per sample; periphyton 

toplankton, four sites per day for three people p

laboratory day per field day; sediment chemistr

sites per day for two people; fish tissue, one site 

day for two people plus one laboratory day per s

1 Ponded or impounded segements only.

2 Sampling for macrophytes and transparency where appropriate.

Table 7. Resource requirements for an exhaustive approach to Tier I monitoring in the Neponset Basin, Massachusett

[Number of visits per location: One visit may include multiple sampling teams. Type of sampling: B, fecal coliform bacteria; C, chlorophyll-a; F

parmeters; Ft, fish tissue; N, nutrients; Mp, macrophytes; Mv, macroinvertebrates; P, periphyton or phytoplankton; Ss, suspended solids; Sx, sedim

istry and toxicity; T, transparency; --, not applicable; not all sample types are collected at each site visit.]

Water body

Sample collection

Number of 

sampling location

Number of visits 

per location

Total number

of visits Type of sampling

STREAMS

First order.................................. 158 6 948 F, B, Mv

Second order ............................. 58 13 754 F, B, Mv

Third order ................................ 32 13 416 F, B, N, Ss, Mv, P, Sx1, Ft

Fourth order .............................. 13 13 169 F, B, N, Ss, Mv, P, Sx1, Ft, M

Fifth order ................................. 12 13 165 F, B, N, Ss, Mv, P, Sx1, Ft, M

LAKES ........................................ 46 14 644 F, N, Mp, T, C

TOTAL...................................... 319 -- 3,096 --

Water body

Laboratory analyses

Bacteria Nutrients Suspended 

solids

MacroinvertebratesPeriphyton 

or phtyoplankton

Sediment

chemistry

and toxicity

Fish

tissue

STREAMS

First order....................... 948 -- -- 158 -- -- -- 

Second order .................. 754 -- -- 58 -- -- -- 

Third order ..................... 416 256 416 32 32 32 14 

Fourth order ................... 169 104 169 7 7 13 5 

Fifth order ...................... 156 96 156 6 6 12 6 

LAKES ............................. -- 46 -- -- -- -- -- 

TOTAL........................... 2,443 502 741 261 45 57 25 
30 Statewide Water-Quality Network for Massachusetts

and lakes, one to two days per site for two people (A.S. 

Johnson, Massachusetts Department of Environmental 

Protection, oral commun., 1999 and 2000). The personnel estimates for stream sampling assume that isokinetic depth- and width-integrated samples would not be 

taken. According to these estimates, 2,661 personneldays (12.1 full-time equivalent employees, or FTEs) 

would be required for sample collection alone. Note 

that most of these activities would occur between 

March and October, so that the number of people 

conducting sampling in those months would be greater 

than the FTE estimates indicate. The number of laboratory analysis range from 25 for fish tissue to 2,443 for 

bacteria, for a total of 4,718 analyses (table 7). 

Resources (primarily personnel) also would be needed 

for final site selection, obtaining permissions from 

private landowners, field-work preparation, data 

management, and data analysis. Note that these 

resource estimates would have been greater by about 

one-third without the reductions in sampling density 

for large streams described previously.

Analysis of the 1994 Neponset 

Water-Resource Assessment

In the early 1990s, the DEP/DEM led a group of 

agencies within the Massachusetts EOEA in an indepth assessment of water resources in the Neponset 

River Basin (1994 Neponset assessment; Kennedy and 

others, 1995). This work was conducted as a pilot for 

the MWI and involved environmental monitoring as 

well as review of discharge and water-withdrawal 

permits, water use, and streamflow in the basin. Types 

of monitoring included physical and chemical monitoring, bacteria sampling, sampling for sediment chemistry and toxicity, and biological monitoring. About 40 to 

50 sampling sites were monitored with about 250 site 

visits. Objectives for the monitoring program were 

(1) to provide information on current water-quality 

conditions in the basin and toxic contaminants at 

specific locations, (2) to identify sources of bacterial 

contamination, (3) to assess the biological integrity of 

the Neponset River and specific tributaries, (4) to 

identify priority non-point-source pollution sou

and (5) to conduct an overall assessment and de

the use-support status with respect to State wate

ity standards of water resources in the basin (Ke

and others, 1995, p. 1-2 to 1-3). Thus, the 1994 

set assessment was intended to address multiple 

mation needs, only one of which was the use-su

assessment of the CWA. In addition, the assessm

existing conditions and use support was not inte

be comprehensive, in the sense of providing inf

tion on 100 percent of the water bodies in the b

However, a comparison of the monitoring progr

results of the 1994 assessment with the goals an

requirements of a comprehensive assessment pr

useful information for the design of a monitorin

gram within constraints of limited resources an

ple information needs. 

About one-half of the total number of per

stream miles in the Neponset basin were report

assessed for overall use support in the 1994 stu

(fig. 5; Kennedy and others, 1995). One-half of 

stream miles also were assessed for specific use

contact recreation (primary and secondary) and 

life based on field water-quality parameters. Sm

fractions of stream miles were assessed for aqu

use based on sediment chemistry and biology, f

consumption, and for aesthetics. These values o

stream miles for assessed reaches were determi

identifying the reaches in the DEP SARIS inven

(Halliwell and others, 1982) and summing the l

of their component stream segments (where seg

lengths were determined as described in the app

these calculated lengths generally were similar 

lengths reported in Halliwell and others, 1982).

Streams reported as assessed in the 1994 

corresponded to the mainstem Neponset River, 

Branch Neponset River, and their major tributar

Thus, all fourth- and fifth-order stream miles an

(86 percent) third-order stream miles in the bas

assessed for recreational and aquatic life (field 

quality parameters) uses; overall use support al

considered assessed for these stream miles. Mos

than 90 percent) fourth- and fifth-order streams 

were assessed for the other designated uses (exc

2An alternative approach to calculating the numbers of assessed stream miles would have been to use the lengths of the indiv

stream segments (as delineated in the present study) on which the 1994 sites were located, rather than the lengths of the entire SA

inventoried stream. That approach would have yielded lower values for assessed stream miles; however, it also would have impose

definitions proposed in the present study, of how to delineate stream reaches with uniform water quality, upon the 1994 study and 

considered appropriate.
Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assess

DESIGNATED USE

0

160

20

40

60

80

100

120

140

STREAM MILES

FIFTH ORDER

FOURTH ORDER

THIRD ORDER

SECOND ORDER

FIRST ORDER

TOTAL

STREAM 

MILES

OVERALL

USE

CONTACT

RECREATION

AQUATIC LIFE–

WATER

QUALITY

AQUATIC LIFE–

SEDIMENT

QUALITY

AQUATIC LIFE–

BIOLOGY

FISH

CONSUMPTION

AESTHETI

49 49 or 11

9

9

1

41 49 NUMBER OF SAMPLES

fish consumption); assessed fractions of third-order 

streams varied by use (15 to 75 percent). Less than onehalf of the second-order stream miles and less than 

one-third of the first-order stream miles were assessed 

for any use. The unassessed small streams were primarily tributaries to the major named tributaries and mainstem rivers in the basin. Because these streams are 

numerous, their exclusion from the assessed population 

results in a large fraction (50 percent) of the stream 

miles in the basin unevaluated for support of their 

designated uses. Moreover, the site-selection procedures, which appear to have followed a targeted 

approach where specific reaches were identified for 

sampling based on known problems or other reasons, 

makes it difficult to extrapolate conditions in the 

assessed streams to the remaining streams. 

The sampling density of the 1994 assessment for 

streams was less than that of the proposed exhaustive 

approach both temporally and spatially. The sampling 

density averaged 2 mi per sample for the recreational 

uses and aquatic life use based on field parameters; 3, 

5, and 7 mi per sample for aquatic life use, based on 

sediment chemistry, biology, and water chemist

respectively; and 21 mi per sample for fish cons

tion (fig. 5). Single samples generally were use

assess the entire lengths of major tributaries, th

Branch Neponset River, and the mainstem Nepo

River for aquatic life use in terms of sediment q

or water chemistry. Use support for contact recr

and for aquatic life use in terms of dissolved ox

and other field parameters was determined from 

samples from about three dates per site in the su

period, one of which was 2 days after significan

cipitation (Kennedy and others, 1995); addition

solved-oxygen samples documenting daily low 

were used for some sites. Thus, temporal variab

bacteria and dissolved oxygen during wet weath

not have been well characterized at some sites. 

Thirty-five lakes were wholly or partially 

assessed for three designated uses in the 1994 a

ment. Monitoring consisted of one site visit per 

to determine macrophyte cover, the presence of 

native or nuisance vegetation, and transparency 

disk or visual estimate), observed from one or m

Figure 5. Total perennial stream miles in the Neponset Basin and assessed miles by stream order and designated u

from the 1994 Neponset water-resource assessment. Numbers above bars are the number of samples on which th

assessments were based. Numbers for aquatic-life use based on water quality represent samples for dissolved 

oxygen and other field parameters (49 samples) or chemical concentrations (11 samples). No information was 

available on sample number for the aesthetics use. Data from Kennedy and others (1995).
32 Statewide Water-Quality Network for Massachusetts

sampling points. The use support assessment for 

secondary contact recreation was based on macrophyte 

cover. Primary contact recreation and aquatic life uses 

were assessed in a limited way, using macrophyte 

cover and transparency, rather than bacteria or chemical data, which were not collected (Kennedy and 

others, 1995). Where macrophyte cover was 

substantial, lakes were reported as impaired for 

aquatic life and recreational uses; otherwise lakes 

were not assessed for these uses. Using this approach, 

26 and 15 lakes were reported as impaired for the 

primary contact recreation and aquatic life uses, 

respectively. Lake acres supporting these uses could 

not be identified. The fish consumption use was 

assessed for one lake only. Thus, a minimal amount of 

data was available for the use-support determinations 

for lakes. Criteria for including lakes in the assessment 

were not reported. The 35 lakes assessed for secondary 

contact recreation represented about one-half of the 

PALIS-coded lakes (Ackerman and others, 1984; 

Ackerman, 1989), typically including all lakes greater 

than 10 acres but some of the smaller lakes (3 to 5 

acres) as well. The 35 lakes accounted for 76 percent of 

the total lake acres and about 90 percent of the acres of 

significant lakes (lakes larger than 5 acres). 

Combined ProbabilisticDeterministic Approach

Investigation of the exhaustive approach and 

analysis of the MWI pilot monitoring program demonstrates the resource-based problems posed by the many 

small streams in a basin and illustrates the difficulties 

in determining sampling densities for Tier I monitoring. For small streams, a probabilistic approach would 

be advantageous, in that this approach would provide 

some information about all small streams without the 

prohibitive resource investment required to sample all 

of them. The information generated by a probabilistic 

monitoring program could be sufficient to meet the 

CWA assessment and reporting requirements for all 

streams in a basin (S. Paulsen, U.S. Environmental 

Protection Agency, National Health and Environmental 

Effects Research Laboratory, oral commun., 1999). 

However, the DEP and MWI teams require information 

about water-quality conditions in all mainstem rivers 

and major tributaries in a basin, for objectives of the 

Clean Water Act and other purposes beyond that of the 

305(b) assessment of use-support status. Specifically, 

information is needed to identify impaired reac

determine causes and sources of impairment, an

target control strategies (A.S. Johnson, Massach

Department of Environmental Protection, writte

commun., 1999). Thus, a monitoring program i

described in this section that combines probabil

sampling for small streams with deterministic sa

on large streams that is intended to meet Tier I 

tives while also providing information to meet o

important water-quality needs in Massachusetts

lakes, both probabilistic and deterministic progr

discussed. Resource limitations also are addres

reducing the number of sampling parameters, su

data are collected to evaluate only some, not all

applicable numeric and narrative State water-qu

standards at some sites. Sampling-density issue

(spatial density and frequency) remain a proble

are discussed further in this section. The monito

approach described in this section is intended to 

implemented in conjunction with the MWI initi

such that sampling would be conducted at 5-ye

intervals on a rotating basis in each of the 27 m

river basins.

Sampling Sites, Parameters, 

Frequency, and Resource 

Requirements for Streams

Probabilistic Sampling Program

Probabilistic sampling is proposed for fir

second-, and third-order perennial streams in ea

basin. In the Neponset Basin, first- and some se

order streams are primarily headwater streams; 

order and second-order streams are the upper re

of, and major tributaries to, the mainstem Nepon

East Branch Neponset Rivers (fig. 4). These str

are proposed for probabilistic monitoring becau

their large number and because, as smaller, hea

streams, many may be less likely to be impaired

Multiple approaches are possible for site selecti

sampling parameters and frequency on these str

Previous and ongoing programs in other States 

reviewed to provide background information an

cuss advantages and disadvantages of different 

approaches to probabilistic monitoring. 

Probabilistic sampling programs for state

biomonitoring surveys were conducted in Mary

and Delaware in the early 1990s. In the Maryla

assessment, sampling sites were selected on firs

second-, and third-order streams by dividing all 
Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assess

wadeable streams (impounded, nonwadeable reaches 

were excluded from the assessment) into 246-foot 

(75-meter) segments in a digital data layer and 

randomly selecting segments for sampling (Roth, 

1997a, 1997b). Eighteen basins in three regions were 

sampled over a 3-year period (2 basins per region per 

year), with the number of sampling sites distributed 

proportionately according to the stream miles per 

basin and stream order. One basin in each region was 

sampled in two consecutive years to measure betweenyear variability (Roth and others, 1997b). In the first 

year of the program (1995), 284 sites were sampled for 

biological, chemical, and physical parameters. Data 

from this program were successfully analyzed to calculate percentages of stream miles that were biologically 

degraded, acidic, or had poor habitat conditions as well 

as to relate these estimates to land use (Roth and 

others, 1997b). Disadvantages of the approach were 

problems in its field implementation, including the 

inability to access or sample some of the selected 

segments or difficulty in obtaining permission for 

sampling from private land owners (Maryland 

Department of Natural Resources, oral commun., 

1999). 

In the Delaware assessment for 305(b) reporting 

in 1993, sites were randomly selected from about 3,300 

potential sampling locations on all nontidal streams in 

the State; the potential sampling points were at the 

intersections of streams and roads and were identified 

in GIS (J.R. Maxted, Delaware Department of Natural 

Resources and Environmental Control, Dover, Del., 

written commun., 1998, 2000). Sampling sites were 

distributed among 35 major watersheds according to 

the distribution of stream miles, to avoid bias associated with the uneven distribution of roads in the State. 

This approach had an advantage in that it was not necessary to obtain permissions from private land owners 

and that sites were easy to access. However, subsequent 

analysis determined that sampling at road crossings 

was likely to provide a biased estimate (worse than 

actual) of water-quality conditions in the assessment 

area (J.R. Maxted, written commun., 2000). 

Probabilistic monitoring programs also have 

been initiated in several other States. In New Jersey, 

40 random sampling sites, used for a statewide status 

assessment, are part of a larger ambient monitoring 

program that includes 6 background, 20 watersh

integrator, 40 land-use indicator, and 10 additio

targeted sampling sites per year (Jacob Gibs, U

Geological Survey, West Trenton, N.J., written 

mun., 1998). Sites are randomly selected from a

ing network of biomonitoring sites for repeated 

times) sampling each year for physical, chemic

sanitary microbiological indicator organism (5 t

30 days) monitoring; these sites are distributed 

graphically so that 2 sites are chosen in each of 

water-management areas in the State. 

In Indiana, Kentucky, and South Carolina

probabilistic monitoring programs for 305(b) as

ments are underway that have been designed in 

oration with the USEPA Regional Environment

Monitoring and Assessment Program (R-EMAP

Olsen, U.S. Environmental Protection Agency, 

Corvallis, Oreg., oral commun., 2000). The pro

are designed on 5-year cycles. Points are rando

selected along the USEPA NHD river reach file

(1:100,000 scale) as sampling sites. In Kentuck

Indiana, probabilistic monitoring on all streams 

State is being implemented as part of 5-year, ro

basin plans similar to the MWI (Kentucky Divi

Water, 1997; A. Garceau, Indiana Department o

Environmental Management, personal commun

2000). In Kentucky, 1 to 3 of 12 major basins in 

State are monitored during the assessment phas

the program. A current monitoring plan include

35 probabilistic sites in each of 2 major basins, 

are sampled once for macroinvertebrates and ha

and are used to assess the aquatic life use (Woo

and others, 1999). These sites are supplemented 

sampling of 14 long-term fixed sites on large riv

(physical, chemical, and biological monitoring) 

about 250 targeted biomonitoring sites on nearl

fourth-order streams in the 2 major basins3. In t

Indiana program, 40 to 64 sites have been samp

in about 2 basins per year for the past 5 years 

(A. Garceau, Indiana Department of Environme

Management, personal commun., 2000). Sites a

sampled three times per year for physical and ch

parameters and once for biological parameters. 

program requires four FTEs and two summer in

each year. A pre-survey is conducted in early sp

locate the preselected sites in the field and obta

3Multiple groups are responsible for sample collection from this large number of sites, including the Kentucky Division of W

Kentucky Fish and Wildlife, a university, and several Federal agencies (Wood and others, 1999).
34 Statewide Water-Quality Network for Massachusetts

permissions. The probabilistic sampling is part of a 

larger program that includes targeted sites for indicator 

bacteria (about 150 sites, sampled 5 times in a 30-day 

period) and pesticides (about 23 sites, sampled once) 

and fixed stations for physical and chemical parameters 

(160 sites, sampled monthly; A. Garceau, Indiana 

Department of Environmental Management, personal 

commun., 2000). In the South Carolina programs, 

about 30 randomly selected sites distributed across the 

State are sampled each year, such that monitoring 

results from about 150 sites are available for a statewide assessment after 5 years. (A.R. Olsen, U.S. 

Environmental Protection Agency, Corvallis, Oreg., 

oral commun., 2000). Advantages of the South Carolina program are that estimates of water-quality conditions for the entire state (although of lower precision 

than the 5-year estimate) can be made each year, and 

the effects of year-to-year climate variations are minimized. In the Kentucky and Indiana programs, statewide estimates are made by combining basin estimates 

from a 5-year cycle; potential yearly climate variations 

could introduce bias into these statewide assessments. 

On the other hand, estimate of water-quality conditions 

and impaired stream miles can be made at the basin as 

well as the statewide scale from these programs, which 

are not possible with the South Carolina approach as 

described.

The probabilistic-based monitoring proposed 

for Massachusetts is similar to the more recent State 

programs in that it would consist of a relatively small 

number of sites and be part of a larger monitoring program. Procedures are needed for new site selection, as 

in most of the programs described. Potential site selection approaches based on these experiences include: 

(1) systematically dividing the streams into segments 

defined by physical features (tributary confluences, 

lakes, and point-source discharges) that potentially 

alter water quality, as described in the Neponset analysis, and randomly selecting segments for sampling; 

(2) dividing the streams into short, uniform reaches and 

randomly selecting reaches for sampling as in the 

Maryland program; and (3) randomly selecting point 

sampling locations along the stream network, as in the 

South Carolina and Kentucky programs; the Delaware 

approach of selecting sites from road crossings is not 

considered because of its potential bias. Approaches 

(2) and (3) are likely to be very similar in practice, 

depending on the reach length in (2) and the flexibility 

allowed to the sampling team to search within some 

buffer distance around the precise point location 

chosen in (3) for a suitable sampling site. Appro

differs from these in that every stream segment

than every point on the stream segment, has an 

chance of being selected for sampling in this ap

It is based on an assumption that the segmentat

scheme provides the best available criteria for p

defining reaches with relatively uniform water q

This assumption is supported by the use of phy

features representing potential contaminant inp

(tributary confluences and point sources) and ch

flow conditions (lakes) to define stream segmen

Approach (1) has the advantage that sampling s

immediately downstream of these features can b

avoided, thereby maximizing the length of strea

acterized by each sample. In addition, problems 

access and permissions may be reduced, becaus

are likely to be multiple points along a segment 

suitable for sampling from which a precise sam

point could be chosen. 

A problem with approach (1), however, i

the assumption of uniform water quality within 

ments may not always be valid. For example, ch

land uses and variable contaminant inputs from 

point sources along a reach are not well represe

a stream-segmentation scheme based on tributa

lakes, and point sources. The alternative approa

(2) and (3), above, to randomly select points or 

reaches along the continuous stream network, m

no assumptions about the length of stream that 

sampling point represents. While necessary for 

exhaustive or targeted approach, such assumpti

not needed to estimate the proportion of stream 

in an area that meet or fail to meet water-quality 

dards with a probabilistic approach, because it i

necessary with the probabilistic approach to rel

monitoring results from a point sampling locati

any particular length of stream. Thus, a site sele

scheme that does not predefine stream reaches, 

avoiding assumptions about water quality, migh

most appropriate for the Tier I probabilistic mon

proposed for small streams in Massachusetts.

The USEPA R-EMAP program has devel

several procedures for site selection using digit

hydrographic data for a probabilistic monitorin

program. Alternative designs select sites for a s

random sample, a stratified random sample, an u

probability sample, or a spatially balanced samp

(A.R. Olsen, U.S. Environmental Protection Ag

Corvallis, Oreg., written commun., 2000). A sim

random sample, which has no weighting or othe
Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assess

discrimination among potential sites, is easiest to 

implement and analyze but provides the least precise 

estimates, because it incorporates no knowledge of 

existing conditions. A stratified random sample allows 

for estimates of conditions within subpopulations of 

the target population, which may be defined based on 

supplementary knowledge, such that estimates for individual subpopulations are more precise than the overall 

estimate; however, more samples are needed than in the 

simple random sample, because the same number of 

samples are needed for each strata as for the entire total 

simple random program. In an unequal probability 

sample, site selection is weighted based on defined 

categories (such as stream order or geographic area) 

such that streams from some categories have a greater 

or lesser likelihood of being selected than would otherwise result from their number. Results from an unequal 

probability sample are analyzed using weighting 

factors that adjust for the numerical proportion of each 

category relative to the total population. Finally, in a 

spatially distributed or “balanced” sample, the spatial 

distribution of sampling sites and the target population 

are similar, which results in a more precise estimate; 

thus, sampling sites would be distributed in a basin in 

the same way as the streams are distributed, and 

“clumping” of sites would be avoided. 

Because the objective of the Massachusetts 

monitoring program is an unbiased estimate of conditions in small streams in the State, a simple 

(unweighted), spatially distributed design might be 

most appropriate for the proposed probabilistic 

sampling. A simple random sample is likely to be 

dominated by samples on first-order streams. An 

unequal probability sample, designed so that all stream 

orders were equally likely to be sampled, might be 

used, and could be considered to provide a more 

unbiased estimate of streams in terms of water volume 

in an area (assuming that higher-order streams represent more flow); alternatively, such a weighted estimate 

might be considered more biased because the larger 

streams in the population, which might be more likely 

to be impaired, would be oversampled in terms of 

stream miles relative to small streams. These potentially ambiguous interpretations suggest that a simple 

random sample might be preferable. Use of a 

spatially distributed design is suggested because of the 

increased precision of this approach (A. Olsen, U.S. 

Environmental Protection Agency, Corvallis, Oreg., 

written commun., 2000). Collaboration with USEPA 

R-EMAP might be an efficient and effective way to 

select sites for the probabilistic monitoring prog

Massachusetts. However, it is proposed that the 

GIS hydrographic data (1:25,000) be used for s

selection rather than the NHD (or RF3, at 1:100

scale), because the MassGIS data provide the m

to-date, accurate, and widely used digital hydro

for Massachusetts. Use of these data will likely 

mize the problems commonly encountered with 

implementation of probabilistic sampling progr

such as the preselection of sites that don’t exist 

otherwise not suitable for sampling.

The number of sampling sites to include 

program depends on the objectives, the level of 

dence and desired precision for the status estim

and the resources available for the program. Th

estimates yielded by the probabilistic sampling 

terms of the number of sites among all sampled 

meeting water-quality standards (or some other 

tion of status). This proportion is taken to repre

proportion of stream miles in the sampled area m

water-quality standards. If program objectives r

status estimates for each individual basin as we

the State as a whole, then many more samples w

needed. A design to meet these objectives is ess

a stratified random design with strata defined by 

basin areas, such as in the Kentucky and Indian

programs described previously. The precision o

status estimate is represented as a confidence in

which is a range of proportion values (as percen

will include the true value with a specified prob

A more precise estimate is represented by a nar

range of values, or smaller confidence interval. 

probability that the interval in fact contains the 

value of the proportion is its confidence level. F

example, a 90-percent confidence interval aroun

the proportion estimate includes the true value o

average 90 percent of the time, whereas a 95-pe

confidence interval includes the true value 95 p

of the time (Helsel and Hirsch, 1992). The confi

interval can be calculated in advance of samplin

from the number of sampling sites and the valu

the proportion (for example, of sites or stream m

being estimated (a proportion of 0.5 can be assu

yield a conservative precision estimate; A. Olse

Environmental Protection Agency, Corvallis, O

written commun., 2000). The equation is as foll

(Schaeffer and McClave, 1982):
36 Statewide Water-Quality Network for Massachusetts

,

where 

is the observed proportion of sites meeting 

water-quality standards (or some other 

definition of status)

n is the number of sampling sites

p is the true probability of observing a site that 

meets water-quality standards, which is 

estimated by 

is the area under the normal distribution curve 

for alpha (α) values equal to [1 - confidence 

level]; equal to 1.645 for a 90-percent 

confidence level and 1.96 for a 95-percent 

confidence level.

Increasing the number of sampling sites increases the 

precision (narrower confidence interval) for a given 

confidence level. Thus, confidence intervals (in 

percent) associated with an assumed proportion of 50 

percent of streams in an area meeting water-quality 

standards would be +16 percent for a sample size of 25, 

+12 percent for a sample size of 50, and +8 percent 

for a sample size of 100, with a 90-percent confidence 

level; with a 95-percent confidence level, the same 

sample sizes would result in estimates of +20, +13, 

and +10 percent, respectively (A. Olsen, U.S. Environmental Protection Agency, Corvallis, Oreg., written 

commun., 2000; these values are based on a simple 

random sample). If the observed proportion of streams 

meeting water-quality standards were less or more than 

50 percent, the calculated confidence intervals would 

be narrower. Thus, a range of sample sizes might be 

considered to provide adequate estimates of the proportion of stream miles in an area meeting water-quality 

standards. In most cases, resource limitations will 

ultimately decide the precise number of sampling sites 

used, once the program objectives have been defined. 

However, some sample sizes clearly would be too 

small to provide adequate status estimates. For example, a sample size of 10 would result in a confidence 

interval (precision) of +26 percent for an estimate of 50 

percent of streams meeting standards with a 90-percent 

confidence level; in other words, it could be stated with 

a 90-percent probability of being true that somewhere 

between 24 to 76 percent of the stream miles in the 

sampled area met standards, based on this sample size. 

This range might be considered too large to pro

useful information for the question of whether t

streams in the sampled area met their designate

A Massachusetts program would likely b

mented in about five basins per year. Thus, a sa

size of 30 to 50 sites per basin, yielding a 90-pe

confidence-interval estimate of about +15 to +1

percent around a proportion of 50 percent, wou

require 150 to 250 sites statewide. This samplin

density would support status estimates for indiv

basins, but may be too many sites to implement

realistic resource limitations. On the other hand

sample size of 30 to 50 sites statewide would li

too small to provide individual status estimates f

basin. Moreover, the annual estimate based on t

sampling sites would be applicable only to area

the State within the sampled basins, considered 

A better approach might be to select 30 to 50 si

statewide each year, such as in the South Caroli

program, with the potential for additional sites 

5 assessment-year basins if better representation 

those basins is desired. This alternative presents 

opportunity for the use of volunteer monitors, c

nated through the MWI teams, to collect data at 

tional sites to monitor basins more densely whe

individual status estimates are desired. This wo

work best in basins where volunteer groups wit

tively sophisticated monitoring capabilities and 

zation structures already exist. Careful planning 

oversight of the volunteer program would likely 

necessary to ensure data quality and comparabi

among basins and with DEP/DWM data. Clearl

sions about sample sizes and implementation of 

probabilistic approach require management-leve

and are likely to be based on considerations abo

importance of Tier I probabilistic monitoring fo

305(b) reporting relative to other aspects of a st

monitoring program. 

For the Massachusetts program, macroinv

brate and bacteria (fecal coliform and E. coli) sa

are proposed for probabilistic sites on small stre

(table 8). This will allow use-support status (tha

impaired or not impaired) to be determined for 

small streams for aquatic life and contact recrea

uses statewide and possibly per basin. Macroinv

brate sampling is proposed once per assessmen

bacteria sampling is proposed monthly from M

mid-October (eight samples). Note that the statu

assessments for individual basins that incorpora

y

n

-- zα ⁄ 2 ± p( ) 1 – p

n • --------------------

y

n

--

y

n

--

zα ⁄ 2
Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assess

volunteer monitoring data, if that approach is used to 

increase sample sizes in some basins, could be less 

rigorous than the statewide assessment depending on 

the macroinvertebrate biomonitoring protocols 

followed by the volunteer monitors. Volunteer monitoring also would be very useful in bacteria sampling at 

probabilistic sampling sites, because the frequent 

sampling necessary for bacteria greatly adds to the 

resource requirements needed for the probabilistic 

monitoring program. 

Sampling for field parameters also is prop

at probabilistic sites, for the aquatic life use and 

provide general water-quality information. Fiel

parameters also could provide some informatio

determine causes of impairment. For example, l

dissolved oxygen could be identified as an impa

cause, although, as discussed previously, 

measurements made at the times of other sampli

not be ideal for identifying “worst case” conditi

(which for dissolved oxygen would occur in pre

hours). Other sampling to determine causes or s

1 Wadeable segments only. 2 Sampling for transparency and macrophytes where appropriate.

Table 8. Sampling parameters and frequency for a combined probabilistic-deterministic approach to Tier I monitoring i

Neponset Basin, Massachusetts

[Monitoring approach: D, deterministic; P, probabilistic; --, not sampled]

Water body

Monitoring 

approach

Sampling parameters

Field

parameters 

Bacteria and

suspended

solids

Nutrients Macroinvertebrates

Periph

phtyop

STREAMS

First, second, and

third order ........ P monthly, March–

October

monthly, March–

October

-- once per 

assessment

Third order ........... D monthly, March–

October; plus 

5 wet weather

monthly, March–

October; plus 

5 wet weather

8 samples, 

March–

October

once per 

assessment

once p

asse

Fourth and 

fifth order ......... D monthly, March–

October plus 

5 wet weather

monthly, March–

October; plus 

5 wet weather

8 samples, 

March–

October

once per 

assessment1

once p

asse

LAKES ................... P or D spring, mid-summer, 

and fall

-- once per assessment; 

spring

-- 

Water body

Monitoring 

approach

Sampling parameters

Sediment

chemistry

and toxicity

Fish 

tissue Macrophtyes Transparency Chlorop

STREAMS

First, second, and 

 third order ....... P -- -- -- -- --

Third order ........... D once per

assessment

-- -- -- --

Fourth and fifth 

 order ................ D once per 

assessment

once per 

assessment

once per 

assessment2

once per 

assessment2

--

LAKES .................... P or D -- -- once per assessment, 

mid-summer

semi-monthly, 

March–October

semi-month

March–O
38 Statewide Water-Quality Network for Massachusetts

is not proposed; macroinvertebrate community, as a 

response variable, will not determine causes or sources, 

although its ancillary information may be useful for 

this purpose. For example, the habitat analysis 

conducted as part of the macroinvertebrate biomonitoring could be used to identify sediment as an impairment cause. Information on causes and sources of 

impairment, however, is probably most useful when 

collected for specific reaches where remedial actions 

can be implemented, rather than at the large scale at 

which it would be provided by the probabilistic 

program. Sampling is not proposed to provide information to the assess all standards relevant to the aquatic 

life and recreational uses (table 2). Data also will not 

routinely be provided to determine use-support status 

for fish consumption. Fish consumption is assumed to 

be less relevant to the small streams sampled with 

probabilistic sites; third-order streams for which fish 

consumption is more relevant could be sampled in the 

deterministic part of the Tier I monitoring program. 

Some water-chemistry constituents that do not require 

specialized sampling techniques could be added for 

probabilistic sites. This would add relatively little to the 

costs of the monitoring program, because a large part 

of the cost of sample collection is for personnel making 

the site visit. Dissolved nutrients would be an example 

of constituents that could easily be added.

The resources required to implement the probabilistic sampling component of the Tier I monitoring 

program for streams will ultimately depend on the 

number of sampling sites selected. Based on previous 

estimates of time required for bacteria and macroinvertebrate sampling, a sampling program with 30 to 

50 sites statewide would require about 171 to 285 

personnel-days (0.8 to 1.3 FTE) for sample collection 

and processing. Additional time would be required for 

site selection, a pre-sampling survey of sites, and 

obtaining permissions from land owners for access and 

sampling, field work preparation, data management, 

and data analysis; the pre-sampling survey might 

require one to two months of time (A. Garceau, Indiana 

Department of Environmental Management, personal 

commun., 2000). Laboratory analyses are given in 

table 9. If status assessments were required for individual basins, these resource requirements would be multiplied by the number of basins (typically five) separately 

assessed. 

Deterministic Sampling Program

Deterministic or targeted sampling is pro

for fourth-, fifth- (and larger), and some third-o

streams in each basin. In the Neponset Basin, fo

and fifth-order streams are the middle and lowe

reaches of the mainstem Neponset and East Bra

Neponset Rivers (fig. 6). Third-order streams ar

major tributaries to and the upper reaches of the

rivers. In general for basins statewide, fourth-, fi

and the larger third-order streams would be defi

as mainstem rivers in major basins, their major 

ies (streams draining the DEM-defined tributary 

watersheds), and other mid-sized streams in wh

DEP/DWM has a special interest. Deterministic 

sampling is proposed to meet DEP/DWM’s nee

information on water-quality conditions on spec

reaches of these streams. 

To design a deterministic sampling progr

large streams, the length of stream represented 

single sampling point must be determined. It is 

possible to do this in the absence of site-specifi

information on hydrologic conditions and the d

tion of potential point and non-point contamina

sources near the sampling point. The length of 

represented by a sampling point, and the import

tures for determining those lengths, also may va

sampling parameter. For example, a sampling s

be representative of a greater stream distance fo

solved constituent such as nitrate than for a con

that tends to be transported in association with 

lates, such as phosphorus or metals, when low-v

impounded reaches, where deposition may occu

near the sampling site. Representative stream le

for indicator bacteria are even more variable, be

factors such as temperature, light, die-off, and b

cal interactions may also affect in-stream bacter

centrations (Bowie and others, 1985). Thus gen

estimates of representative stream lengths for sa

sites made in advance of sampling are necessar

trary assumptions, that often rely on “rules of th

such as 40 times the stream width. 

For the purposes of this report, an arbitra

pling density of about 5 mi per sample is propo

deterministic sampling of fourth-, fifth, and thir

streams for Tier I monitoring. This is consistent 

USEPA’s general recommendation that samplin

should be considered to represent a maximum o

10 mi for wadeable streams and 25 mi for large 

(U.S. Environmental Protection Agency, 1997b
Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assess

comparison, representative distances equal to 40 times 

stream widths are about 0.5 mi, with shorter distances 

for high-sloped streams and longer distances for lowsloped streams, based on width measurements for a 

limited number of major tributaries and smaller mainstem streams in Massachusetts (Parker and Gay, 1987; 

Parker and DeSimone, 1992). The arbitrary 5-mile 

sampling density differs from the systematic approach 

to defining stream reaches with uniform water quality, 

described previously for the exhaustive approach, in 

that its use incorporates no knowledge about how 

water-quality conditions in a stream are expected to 

vary. However, any deterministic (that is, non-probabilistic) approach to choosing sampling locations and 

relating point-sample information to stream lengths is 

subjective and requires assumptions about spatial variability in water quality. Thus, a sampling densit

proposed that is considered reasonable based on 

USEPA’s recommendations, Massachusetts hyd

phy, and realistic resource limitations. 

Choosing sampling sites at 5-mile interva

along fourth- and fifth-order streams in the Nep

Basin, which has 20 mi of these streams, produ

about four sites. It is proposed that the sampling 

sites be located near downstream ends of the str

reach being characterized. The rationale for this 

that downstream locations have the potential fo

capturing the effects of point- and non-point 

contaminant sources and hydrologic conditions 

upstream of the sampling site, whereas sources 

and conditions downstream from a site cannot b

represented by water-quality conditions at the s

1 Ponded or impounded segments only.

2 Sampling for macrophytes and transparency where appropriate.

Table 9. Resource requirements for a combined probabilistic-deterministic approach to Tier I monitoring in the Neponse

Massachusetts

[Number of visits per location: One visit may include multiple sampling teams. Type of sampling: B, bacteria; C, chlorophyll-a; F, field parmete

tissue; Mp, macrophytes; N, nutrients; Mv, macroinvertebrates; P, periphyton or phtyoplankton; Ss, suspended solids; Sx, sediment chemistry and 

T, transparency; not all sample types are collected at each site visit. --, not applicable]

Water body Monitoring 

approach

Sample collection

Number of 

sampling

locations

Number of 

visits per 

location

Total

number

of visits 

Type of sampling

STREAMS

First, second, and third 

order ............................. P 30–50 8 240–400 F, B, Mv

Third order ....................... D

20 13 260

F, B, N, Ss, Mv, P, Mp, T

Fourth and fifth order....... D F, B, N, Ss, Mv, P, Sx1, Ft, Mp

LAKES ............................... P or D 24 14 336 F, N, Mp, T, C

TOTAL............................. 74–94 -- 836–996 --

Water body

Laboratory analyses

Bacteria Nutrients Suspended

solids

MacroinvertebratesPeriphyton 

or phtyoplankton

Sediment 

chemistry

and

toxicity

Fish 

issue

C

STREAMS

First, second, and third 

order ..........................

240–400 -- -- 30–50 -- -- -- 

Third order ....................

260 104 260 10 10 -- -- 

Fourth and fifth order.... 10 10 

LAKES ............................ -- 24 -- -- -- -- -- 

TOTAL.......................... 500–660 128 260 40–60 10 10 10 
ewide Water-Quality Network for Massachusetts

RHODE ISLAND

NEW HAMPSHIRE

CONNECTICUT

VERMONT

NEW YORK

01102500

01104615

01124000

 Ungaged 

Connecticut 

 River

Ungaged 

 Taunton 

 River

01111230

01184000

01198125

01096500 01099500

011055566

01102000

Ungaged

Merrimack river

01125100

01166500

01177000

01170000

01183500 01185500

Map source: USGS, MA-RI District GIS coverages 01108000

42 ̊00'

42 ̊30'

7300

72 ̊30' 72 ̊00' 71 ̊30'

70 ̊00'

41 ̊30'

0 10 20 30 40 50 KILOMETERS

0 10 20 30 40 50 MILES

44 ̊

42 ̊

0 40 80 MILES

0 40 80 KILOMETERS

46 ̊

72 ̊

70 ̊

68 ̊

ATLANTIC OCEAN

MAINE

NEW YORK

CANADA

CANADA

VERMONT

NEW YORK

CONNECTICUT

RHODE

ISLAND

MASSACHUSETTS

NEW

HAMPSHIRE

01111230

EXPLANATION

WATERSHED-DRAINAGE AREAS OF PROPOSED SAMPLING SITES 

 (AREAS OF SOME SITES EXTEND OUTSIDE OF MASSACHUSETTS)

BOUNDARY OF WATERSHED-DRAINAGE AREAS OF PROPOSED

 SAMPLING SITES

PROPOSED SAMPLING SITE—Number is station 

 identifer of existing USGS streamflow gage

CAPE COD 

BAY

ATLANTIC OCEAN

BUZZARDS BAY

VINEYARD SOUND

MUSKEGET CHANNEL

MASSACHUSETTS BAY

IPSWICH BAY

NANTUCKET

SOUND

Figure 6. Locations and watershed-drainage areas of proposed sites for Tier II monitoring in Massachusetts.
Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assess

Thus, it may be more valid to extrapolate monitoring 

results upstream than downstream from a sampling site 

in many cases. Based on these criteria, deterministic 

sampling sites on in the Neponset Basin would include 

sites located (1) near the mouths of the mainstem 

Neponset and East Branch Rivers (two sites); (2) 

upstream of mainstem confluences, which in the 

Neponset Basin would be on the Neponset River 

upstream of the confluence with the East Branch (one 

site); (3) along the middle or upper reaches of the 

Neponset River, located to provide coverage at regular 

spatial intervals from other sites (one site); and (4) 

possibly other sites located upstream of major point 

sources and(or) urban areas (although it should be 

noted that targeting point sources or concentrated nonpoint-source areas with Tier I deterministic sites is 

likely to bias the overall assessment towards problem 

areas). The precise locations of the sites would be 

determined based on local conditions, such as 

wetlands, point sources, and so on.

In addition to sampling sites on the Neponset and 

East Branch Neponset Rivers, deterministic sampling 

sites are proposed for some fraction of their major tributaries, which are mostly third-order streams. Major 

tributaries could be defined by the DEM-delineated 

tributary basins, of which there are 14 in the Neponset 

Basin. Two of these are drained by fourth- or fifthorder mainstem segments, and some tributary watersheds have more than one large stream. Thus, 10 to 

15 sampling sites might be adequate to characterize 

water-quality in major tributaries in the Neponset 

Basin. As with the mainstem sites, sampling sites 

would be proposed near the downstream ends of the 

tributaries, thereby integrating the effects of all sources 

in the watersheds. These sites could be used to characterize the entire length of the tributary or some portion 

that extends to its first- or second-order headwater 

segments. 

Additional sites, for sampling by volunteers for 

some constituents, could be added to increase the 

number of tributary streams that are deterministically 

monitored or to increase the sampling density on mainstem reaches. As with macroinvertebrate sampling at 

probabilistic sites, careful planning, oversight, and 

quality control for volunteer efforts would be needed to 

ensure data quality and comparability. Care also would 

be needed when interpreting data that include these 

sites, so that the additional sites chosen based on local 

interest of volunteer monitors do not unduly bia

deterministic site selection scheme toward prob

areas. 

Sampling parameters proposed for determ

sites include water chemistry, bacteria, fish com

fish tissue, and possibly sediment chemistry and 

ity, macroinvertebrates, and periphyton or phyto

ton (table 8). Water-chemistry and bacteria sam

proposed for third-, fourth-, and fifth-order strea

would be used to assess contact recreation and 

life uses. Parameters include field parameters (t

ture, specific conductance, pH, dissolved oxyge

turbidity), bacteria (fecal coliform and E. coli), 

ents, and suspended sediments. These parameter

be well suited to monitoring by volunteer group

which commonly measured some or all of them 

their own purposes (Dates and others, 2000), th

increasing the number of stream miles determin

cally assessed for contact recreation and aquatic 

uses with water-chemistry. Sampling for periph

phytoplankton community and macroinvertebra

response indicators for aquatic life use, also are 

proposed in large streams where appropriate. Sa

for metals is not routinely proposed for Tier I m

ing, as DEP/DWM has historically used toxicity 

and biomonitoring to determine whether advers

effects of metals have occurred (A.S. Johnson, 

chusetts Department of Environmental Protectio

Division of Watershed Management, written co

2000). Metals sampling could be added, howev

address hot-spot, 303(d), or other site-specific i

tion needs. Fish community measurements and 

tissue sampling for toxic contaminants are prop

fourth- and fifth-order streams to address the aq

life and fish consumption uses, respectively; fis

sampling could be added for third-order stream

appropriate. Sampling for sediment chemistry a

toxicity could be included at depositional areas 

water-chemistry and fish sampling sites, as thes

parameters could be used to assess aquatic life 

Other sites, in large impounded areas of stream

could be added, but may be more appropriate as 

a targeted monitoring program. It is not anticipa

volunteer monitors would have a large role in sa

for metals, fish community or tissue, or sedime

these parameters require relatively sophisticated 

sampling techniques. Macroinvertebrate and pe

ton sampling is proposed for wadeable sites inc

in this program, which are most likely to be the 

order stream sites. Techniques are available for 
42 Statewide Water-Quality Network for Massachusetts

macroinvertebrate sampling on nonwadeable streams 

(for example, Cuffney and others, 1993), but these are 

labor intensive and are not proposed for routine monitoring. Finally, macrophyte cover and transparency 

could be determined on large streams where appropriate, as described for the exhaustive approach.

Repeated sampling is needed to characterize 

many of the sampling parameters proposed for the 

deterministic sites because of their temporal variability. 

However, as with spatial sampling density, it is difficult 

if not impossible to make general determinations in 

advance of data collection of the sampling frequency 

needed to characterize individual water-quality 

parameters at unsampled sites. Generally, the number 

of samples needed to characterize a water-quality 

parameter increases with its variability. Methods are 

available to compute the number of samples needed to 

estimate the mean value of a water-quality parameter at 

a station at known precision and confidence level, if the 

statistical variance of the parameter at the station is 

known (Sanders and others, 1987); however, this information is not available at unsampled sites and can only 

be estimated at sampled sites with large sample 

numbers. Without previous knowledge of the temporal 

variability of water-quality characteristics at individual 

sites, many sampling programs of fixed stations use a 

uniform sampling frequency at all sites that is calendarbased but may include more frequent sampling in some 

months or hydrologic regimes. For example, the USGS 

National Water-Quality Assessment Program sampling 

protocols call for sampling of small and large basins in 

New England (drainage areas ranging from 23 to 

10,000 mi2) 18 times per year at most sites for field 

parameters, nutrients, major ions, and organic carbon 

(U.S. Geological Survey, 2000). These consist of 

monthly samples to capture seasonal variability and six 

additional samples targeted at high and low flows and 

storm runoff. Sampling for pesticides and VOCs, which 

are costly to analyze and potentially less variable, 

occurs once per assessment at some of these sites. 

More intensively monitored sites are sampled more 

frequently, for example weekly from April to August 

and monthly during the rest of the year (30 to 40 total 

samples) for all constituents, including pesticides and 

VOCs. These sampling frequencies are considered 

appropriate for objectives of determining nutrient loads 

to coastal waters and the effects of urban land use on 

stream-water quality (Lopes and Price, 1997; U.S. 

Geological Survey, 2000). 

The number of samples considered adequ

their distribution in time also depends on the obj

of the monitoring program. For example, monito

calculate contaminant loads requires that the var

in concentration of the contaminant be well cha

ized over the range of flows in which the majori

mass is transported. Monitoring to estimate ann

average conditions at a site also requires that se

variation be well characterized. Monitoring for 

status of waters with respect to water-quality sta

as in the Tier I monitoring described in this repo

be understood to call for monitoring during con

when the standards are likely to be violated. Th

sampling may not be needed year round for para

for which impairment would be expected to onl

during summer months. Alternatively, sampling 

the expected impaired period may be considere

bias the assessment towards “worse than averag

conditions. 

Finally, it is important to note that, for an 

ment of existing conditions at the scale of the 3

assessment, it will not be possible to sample fre

enough to characterize individual water quality 

eters with a level of confidence that might be co

ered statistically valid—sample sizes of 20 or 3

site are not realistic for 305(b)-type monitoring. 

it is important to distribute the limited number o

samples that are feasible over the range of cond

with which the parameters are expected to vary

an understanding of those conditions exists. For 

ple, many constituents, particularly those that ar

ported with sediment particles, vary with flow. 

Sampling over the range of expected flow condi

a site would be needed to characterize these par

ters. Other parameters, such as indicator bacteri

highly correlated with wet weather flows, so tha

sampling around storm events is needed. Guidan

is possible from water-quality standards that are 

ten in terms of sample numbers. In most cases, 

however, resource limitations will ultimately de

the number of samples collected per site, becau

sampling frequency (along with site number) is 

primary factor in the overall cost of a monitorin

program (Sanders and others, 1987). 

The sampling frequency proposed for the 

ministic sites reflects both the need for repeated 

sampling for some parameters and a realistic ex

tion of available resources. In addition, it is assu

that sampling can be targeted to expected perio

impairment to meet the objectives of the assess
Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assess

Thus, for bacteria and suspended sediment, the 

proposed sampling frequency is monthly from March 

to mid-October (eight samples, wet or dry weather), 

with the collection of about five additional samples 

during this period targeted at rainfall-runoff events (wet 

weather). Field parameters also would be measured 

with these samples. As described for the exhaustive 

approach, criteria for defining wet- and dry-weather 

periods would be needed. This frequency is greater 

than the sampling frequency for dissolved oxygen and 

bacteria used in the 1994 Neponset assessment. Nutrients are proposed for sampling about monthly from 

March to October (eight samples), with some samples 

taken with the wet-weather bacteria samples as 

described for the exhaustive approach. The wetweather sampling for bacteria, suspended sediment and 

nutrients would be a good opportunity to incorporate 

volunteer monitoring, because it often is difficult and 

costly to deploy agency personnel for storm-event 

sampling. For sampling parameters other than water 

chemistry and bacteria, that is, fish community, fish 

tissue, sediment chemistry and toxicity, macroinvertebrates, and periphyton or phytoplankton, one sample 

per assessment is proposed. These characteristics integrate water-quality conditions over time and are much 

less temporally variable than water chemistry; composite samples or more than one sample per site could be 

considered for parameters, such as sediment chemistry, 

that are highly variable spatially. Volunteer monitoring 

would be less useful for these parameters, because 

specialized sampling techniques are required.

Resource requirements for the deterministic 

monitoring of streams were calculated using the time 

estimates previously described for the exhaustive 

monitoring approach. Estimates were made for the 

Neponset basin (table 9). For water-chemistry and 

bacteria sampling, 20 sites with 13 visits per site were 

assumed, requiring 200 to 264 personnel-days. The 

storm sampling included in these visits will need to 

include extra effort and non-standard working hours 

for agency personnel. Personnel estimates for waterchemistry sampling assume that the isokinetic depthand width-integrated methodology would not be used. 

For fish tissue and sediment chemistry and toxicity, 10 

sites with 1 visit per site also would require 30 and 10 

personnel-days, respectively. Six sites for fish community were assumed, for a total of 12 personnel-days 

(not shown in table 9). Finally, 10 macroinvertebrate 

and periphyton or phytoplankton sites would require 25 

and 12 personnel-days, respectively, including sample 

processing. The total resource requirements for 

deterministic monitoring are 193 personnel-day

about 0.9 FTE; numbers of laboratory analyses 

given in table 9. As with estimates for the exhau

approach, most of these personnel-days would b

needed during late spring, summer, and early fa

These estimates do not include time for site sele

obtaining permissions, field preparation, or data 

management and analysis.

Sampling Sites, Parameters, 

Frequency, and Resource 

Requirements for Lakes

The definition of sampling sites for lakes 

problematic than for streams, in that lakes are d

water bodies. As with streams, it is proposed th

lakes defined in the MassGIS 1:25,000 hydrogr

be used as the basis for selecting lakes for samp

The previously described analysis of lakes in th

Neponset basin identified those lakes larger tha

acres for an exhaustive assessment of lake wate

ity conditions. Forty-six lakes, represented 84 p

of total lake areas in the basin, met this criterion

number of lakes may be too large to allow for a 

ministic approach for the lakes assessment. A la

size criterion, 10 acres, would reduce the numb

lakes included in the assessment for the Nepons

by about half, to 24 lakes, but still assess 77 per

the lake areas in basin. The larger size criterion 

for the present discussion.

A sample number of about 24 lakes per b

suggests that either deterministic (in this case, e

tive) or probabilistic sampling may be possible 

lakes component of Tier I monitoring, within re

resource requirements. A deterministic approach 

provide some site-specific information on all la

included in an assessment, such that impairmen

any one of the lakes potentially could be identifi

remedial actions could be initiated. A probabili

approach would provide information on the ove

status of all lakes as a group, in terms of the stat

respect to the assessed uses, but would only pro

site-specific information on a fraction of the lak

interest in the sampled area. With the same amo

resources, however, the assessments could be m

intensive, in terms of sampling parameters and 

frequency, with the probabilistic approach, beca

it would include fewer sampling sites. 
44 Statewide Water-Quality Network for Massachusetts

Whether a probabilistic or deterministic 

approach is used, sampling for field parameters, macrophytes, Secchi-disk transparency, nutrients, and 

chlorophyll-a is proposed for all lakes included in the 

assessment (table 9). Profiles of field parameters, for 

example at 2- to 3-foot intervals, are proposed for 

spring, mid- to late summer, and fall, from the deepest 

part of each lake. Available bathymetric maps, local 

knowledge, or best judgement would be used to select 

the sampling location. The profile measurements would 

indicate whether the lake becomes thermally stratified, 

and whether dissolved oxygen is depleted at depth; 

dissolved-oxygen depletion indicates lake productivity 

and the potential for mobilization of nutrients (phosphorus) or toxics (ammonia) from bottom sediments. 

These data would be used to assess aquatic life use. 

Macrophyte data would be used for aquatic life use 

along with primary and secondary (boating) recreation 

uses. Proposed measures are percent cover of floatingleaved, emergent, and submerged macrophytes and the 

presence or absence of non-native or nuisance plants, 

measured once in mid- to late summer. Percent cover 

could be estimated through visual inspection (floatingleaved and emergent) or several grab samples 

(submerged) for small lakes or through more quantitative mapping for large lakes. 

Measurements of Secchi-disk depth and chlorophyll-a, which are important indicators of trophic 

status (Carlson, 1977; U.S. Environmental Protection 

Agency, 1998b), also are proposed at each lake. 

Although not linked to a specific designated use or 

State water-quality standard, the trophic state of the 

lakes provides valuable information for a status assessment, because most uses of lakes are adversely affected 

by increasing eutrophication. Secchi disk also could be 

used to assess primary contact recreation (swimming) 

use in terms of the State public-health standard for 

transparency. Secchi disk and chlorophyll-a are 

proposed for semi-monthly measurements from midMarch to mid-October, to capture the temporal variability resulting from phytoplankton population 

changes. The frequent measurements needed for Secchi 

disk and chlorophyll-a in lakes could benefit from the 

use of volunteers, as demonstrated by a recent 

USGS/DEP study (Waldron and others, 2001). Alternatively, less frequent measurements could be made, for 

example, in spring, midsummer, and fall only; with this 

schedule, Secchi-disk data would provide screening 

information only, to identify problem lakes. Volunteers 

also could be used to increase the number of lakes 

assessed in a probabilistic program, although lo

interest in lake quality may be tied to specific, r

than randomly selected, lakes. In addition to Se

disk and chlorophyll-a, measurements of total p

phorus and nitrogen are proposed for lakes once 

assessment, in spring. Nitrogen and phosphorus 

concentrations also are components of trophic i

for lakes (U.S. Environmental Protection Agenc

1998b). Although the temporal variability of the

constituents would not be sampled, the nitrogen 

phosphorus data would be useful to indicate po

problems in some lakes. Phytoplankon commun

analysis would integrate the effects of temporal

able nutrients concentrations and could be very 

for lakes assessments, but is not currently propo

This sampling program proposed for lake

involving water chemistry, Secchi disk, chlorop

and macrophytes, is similar to USEPA’s Tier 1 l

monitoring, which is considered appropriate for 

regional lake assessments (U.S. Environmental 

Protection Agency, 1998b). It provides data prim

for the aquatic life use, and, to a lesser extent, f

contact recreation uses. Routine sampling for fi

tissue, and fish community for the aquatic life a

consumption uses are not proposed, because of 

expected resources limitations. Probabilistic mo

ing of a randomly selected subset of all lakes in 

assessed basins per year for fish tissue could be 

provide an overall status estimate of the fish con

tion use for 305(b) purposes. However, more us

information, in terms of public-health protection

be obtained from a targeted sampling program f

tissue that focuses on lakes identified by DEP/D

and the MWI teams as high priority for the fish 

consumption use. Similarly, bacteria sampling f

swimming use is not proposed as a routine part o

lakes monitoring. Bacteria sampling would requ

repeated site visits, some during wet weather, an

ably multiple samples per lake. Moreover, many 

lakes identified for Tier I assessment may not b

for swimming. Thus, it is proposed that the swi

use be assessed on lakes with public swimming 

beaches only, and that local monitoring data be 

for the assessment. It should be noted, however

bacteria data are not likely to be available for al

beaches, so that an assessment based on local da

will be incomplete even for lakes with public sw

ming. A single “spot-check” sample could be co

on lakes used for swimming during the one-tim

for water chemistry and other parameters, but th
Tier I: Basin-Based Monitoring Program for the Clean Water Act Statewide Assess

would be of limited use given the inherent variability 

of bacteria concentrations. If information is required on 

bacteria concentrations for the swimming use in all 

lakes, a probabilistic approach would be proposed, as 

for the fish consumption use. Finally, the proposed 

sampling program for water chemistry, macrophytes, 

and other indicators for aquatic life use could be 

supplemented with more intensive assessments, with 

repeated sampling during the growing season and 

additional measurements, for specific lakes of interest 

in each basin for purposes other than the Tier I objectives. Volunteers from lake associations could be very 

useful in these more intensive assessments

Resource requirements for lakes monitoring can 

be estimated by assuming that each lake visit requires 

0.5 days for 2 people for sample and field-data collection for most visits and 1 day for 2 people when nutrients, chlorophyll-a, and macrophyte sampling occurs. 

A boat is needed for the site visits, for water-chemistry 

profiles and sample collection from the middle of the 

lake and to facilitate macrophyte surveys. Thus, 408 

personnel-days (about 1.9 FTE) would be needed for 

field work to assess lakes in the Neponset basin, if a 

deterministic approach is used. Most of this time would 

be concentrated in three field-work periods, in spring, 

summer, and fall. Additional time would be needed for 

field preparation, for data analysis and management, 

and possibly for a presampling survey for lake access.

Accurate bathymetry for all lakes would be 

useful for 305(b) assessment objectives as well as for 

objectives of TMDL development. Bathymetric information can be used to locate sampling site(s) on lakes 

for the 305(b) and other monitoring and to estimate 

flushing rates; flushing rates are important for evaluating lakes’ susceptibility to nutrient loading effects and 

are needed for nutrient- or phosphorus-loading models 

such as used in TMDL development. Although not 

included in the scope of the current work, it is 

suggested that a program for measuring bathymetry 

of all lakes be considered. A recording fathometer 

coupled to a global positioning system would efficiently collect profile depth and position data at submeter accuracy for incorporation into a GIS coverage 

of lake bathymetry. The GIS could then be used to map 

the reservoir and compute morphometric features, 

including lake area, volume, maximum depth, mean 

 depth, relative depth, and depth-area and depthvolume relations. 

Statewide Implementation of the 

Combined Probabilistic-Deterministic 

Approach for Tier I Basin-Based Monitoring

Tier I monitoring programs would be imp

mented in conjunction with the 5-year, rotating

schedule of the MWI, as stated previously. The 

sampling program would be most effectively im

mented in Years 2 (research) and 3 (assessment

cycle. Sampling plans developed for each basin 

DEP/DWM for Tier I monitoring could be com

mented with targeted monitoring plans, perhaps 

a fixed number of sites per basin, developed by 

MWI teams. Simultaneous implementation of th

and targeted monitoring programs could enhanc

efficiency and usefulness of both programs.

Special considerations may be needed wh

implementing the probabilistic monitoring prog

statewide. In particular, management-level deci

are needed, based on program and monitoring o

tives as well as on resource limitations, about wh

sampling density should be used that will allow 

assessment of the status of streams (a) within ea

vidual basin (30 or more sites per basin, or 150 o

sites statewide) or (b) aggregated from all samp

basins across the state (30 or more sites statewi

With the latter approach, distribution of the pro

tic sites across the entire State, independent of t

MWI cycle, might be a more effective design fo

statewide estimate. Implementation of the proba

program over multiple 5-year cycles also requir

consideration. In subsequent 5-year cycles, the 

sites in each basin may be resampled, or new sit

be randomly selected. Sampling the same sites i

to provide more information on water-quality tr

over time. However, sites that are sampled in th

cycle and found to be impaired may have receiv

remediation or other special treatment during th

between samplings, such that the sampling sites 

no longer provide an unbiased estimate of ambi

conditions in the second cycle (A. Olsen, U.S. 

Environmental Protection Agency, Corvallis, O

oral commun., 2000).

The resources needed to implement the T

monitoring program across the State may be est

from those determined for the Neponset basin. 

resources were estimated, in terms of personnel

needed for sample collection, from the number 

sampling sites in the basin, the proposed numbe

visits per site, and assumptions about personnel 
46 Statewide Water-Quality Network for Massachusetts

required to collect each sample type. Resource 

estimates for the Neponset Basin, however, cannot be 

simply multiplied by five to obtain resources needed to 

implement the program in five basins each year, 

because the Neponset Basin, at 117 mi2, is considerably smaller than most major basins in the State. The 

27 major basins average about 300 mi2 in area, and the 

areas assessed by MWI basin teams average about 

400 mi2. The Neponset Basin itself is less than one-half 

of the area assessed by the Boston Harbor Watersheds 

team. Thus, many more sites would be needed in most 

basins than determined for the Neponset Basin for the 

two components of the program that vary with the 

number of water bodies being assessed, that is, the 

deterministic monitoring programs for large streams 

and lakes. The number of sampling sites for the probabilistic monitoring program for small streams is the 

same irrespective of the number of stream miles being 

assessed. The number of probabilistic sampling sites 

would substantially increase, however, if management 

decisions were made to assess use-support status of 

small streams individually for each basin included in 

the assessment, rather than to make a statewide assessment only—in the former case, resource requirements 

for the statewide estimate would be multiplied by the 

number of basins (typically five) assessed. With the 

statewide estimate only, about 30 FTEs for field sample 

collection and processing would be needed; this 

assumes that five basins, each requiring about twice the 

effort as the Neponset, are assessed per year. Laboratory analysis for the plan as described would require 

2,840 to 3,000 analyses for bacteria (fecal coliform and 

E. coli), 1,280 analyses for nutrients (total nitrogen and 

total phosphorus or individual species), 2,600 analyses 

for suspended sediment, 130 to 150 macroinvertebrate, 

100 analyses each for periphyton or phytoplankton, fish 

tissue, sediment chemistry, and sediment toxicity, and 

3,660 chlorophyll-a analyses, for a total of 10,510 to 

10,690 laboratory analyses. Personnel requirements for 

field aspects of the program would be needed primarily 

in late spring, summer, and early fall. 

In addition to the personnel resources for field 

sample collection and processing, personnel time will 

be needed for pre-sampling site surveys, obtaining 

permissions, field preparation, data management, and 

other aspects of the program. It is difficult to estimate 

these personnel requirements. Time needed for 

program administration, data management, and similar 

activities is largely dependent on the specifics of the 

program’s operation. For example, personnel time for 

data handling and management will vary depen

whether results are reported from analytical lab

ries in digital or paper form, and on how much 

required to enter the results into the program’s d

storage system. Similarly, time for data reportin

aspects of the monitoring program will vary gre

depending on the specific reporting venues. In t

surface-water sampling component for a typical 

NAWQA program, about 1.5 personnel-days ar

required for field preparation and data managem

each personnel-day spent in the field collecting 

samples; additional personnel time is spent in th

program for administration, planning, and repor

For a USGS-based, statewide monitoring progr

New Jersey, about 1.5 personnel-days are spent 

field preparation, data management, and prepar

data for publication for each personnel-day in th

(Jacob Gibs, U.S. Geological Survey, oral comm

2000). For a recent, less complex USGS sampli

program for bacteria and nutrients in small stre

about 0.5 days were required for field preparati

data management for each field day. These roug

mates suggest that the FTE estimates made for 

data collection components of the proposed mon

program for Massachusetts could be about doub

about 60 FTEs, when time for field preparation 

data management are included. The additional t

project administration, planning, site selection, 

obtaining permissions could add several more F

Again, however, it must be noted that these are 

rough estimates and the actual personnel resour

required by all aspects of the program may vary 

depending on final makeup of the program. The

substantial resource requirements could be redu

eliminating or reducing assessment of some des

uses that require intensive sampling, such as the 

ational use for small streams or frequent sampli

lakes for trophic status, or by using a probabilis

approach for lakes. Finally, in addition to perso

requirements, implementation of the proposed p

would require resources for field supplies, trans

tion, laboratory analyses, and data storage. 

Volunteer monitoring could be used in se

ways to supplement agency resources to meet th

substantial personnel requirements of the propo

program for Tier I monitoring, or to enhance it. 

teers could collect bacteria samples at probabili

deterministic sites, reducing the number of agen

visits needed to these sites. Volunteers would be 
Tier II: Fixed-Station Monitoring Program for Contaminant Loads in Major R

particularly helpful for wet-weather sampling, for 

which it can be difficult and costly to mobilize agency 

sampling teams. For lakes, volunteers could make 

some or all of the frequent Secchi-disk and chlorophyll-a measurements. Volunteer monitoring also could 

be used to provide more intensive assessments of some 

lakes, or to deterministically sample lakes of special 

interest if a probabilistic approach for lakes otherwise 

generally is taken. For streams, volunteer monitoring 

could enhance the proposed program through biomonitoring (macroinvertebrates) and bacteria sampling at 

additional sites on small streams, which otherwise are 

probabilistically sampled statewide, in basins where 

individual status estimates are desired. The status estimates using volunteer data could be less rigorous if less 

sophisticated biomonitoring protocols are followed by 

the volunteer groups than by agency personnel, but still 

could meet information needs for the basin. Finally, 

volunteer monitoring of additional sites on large 

streams could be used to increase the number of thirdorder streams that are deterministically monitored or to 

increase the sampling density on mainstem reaches, 

most likely for aquatic life (water-chemistry sampling) 

or recreational (bacteria sampling) uses. 

Experience gained through implementation of 

the combined probabilistic-deterministic program for 

Tier I monitoring, as with all components of a proposed 

statewide network, would likely suggest ways in which 

the network design could be modified and improved. In 

fact, modifications and flexibility will likely be needed 

following initial implementation of the monitoring 

program. For example, sampling parameters could be 

added or dropped from the program, or sampling 

frequencies could be changed based on the analysis of 

the initially collected data. Careful consideration may 

be needed to ensure that short-term program modifications will not adversely affect the comparability of data 

collected during multi-year assessments. The statewide 

assessment of use-support status, which is a requirement of the CWA, will not be possible to obtain by 

aggregating individual basin-based assessments over 

5-year periods if the sampling program is altered too 

much from year to year or among basins.

TIER II: FIXED-STATION 

MONITORING PROGRAM FOR 

CONTAMINANT LOADS IN 

MAJOR RIVERS

The objective of Tier II of the statewide m

ing program is to determine loads of contamina

carried by major rivers in Massachusetts at stra

locations. This information is needed at the mo

major rivers to quantify loads delivered to coast

waters, such as Boston Harbor, and major inlan

ways, such as the Connecticut River. Informatio

is needed at State boundaries to permit the dete

tion of contaminant loads entering and leaving 

Massachusetts. The sampling approach suited t

loads monitoring objective is fixed-station mon

where the same sites are sampled repeatedly ov

and over a range of hydrologic conditions. Repe

sampling over time also generates data that may 

suitable for determining trends in water-quality 

tions and, over the longer term, for determining 

in contaminant loads. 

Sampling Sites, Parameters, and 

Frequency

Candidate streams for Tier II monitoring 

the mainstem rivers draining the State’s 27 maj

basins. Nineteen sampling locations are propos

generally on the largest rivers in Central, Weste

and Eastern Massachusetts (table 10 and fig. 6)

proposed sampling sites are: near the mouths of 

Merrimack, Aberjona, Charles, Ipswich, Nepon

and Taunton Rivers, which collectively drain to 

Boston Harbor, the Gulf of Maine, and Narrang

Bay; at the mouths of the Millers, Deerfield, Ch

and Westfield Rivers, which discharge to the Co

cut River; at the mouths of the Concord and Na

Rivers, which discharge to the Merrimack Rive

at locations on the Quinebaug, French, Blacksto

West Branch Farmington, Housatonic, and Conn

Rivers near where they enter and(or) leave the S

Because continuous streamflow records are nee

for accurate loads calculations, most of the site

proposed at or near existing gages. The need fo

streamflow data also limits potential sampling 

locations on rivers that drain to the coast to area

are upstream of tidal influences and areas of slu
48 Statewide Water-Quality Network for Massachusetts

flow where streamflow cannot be gaged accurately. In 

most cases, such as on the Charles River and Aberjona 

Rivers, existing gages are already located as far downstream as possible for stream gaging. It may be possible to gage streamflow on the Taunton River further 

downstream than the existing gage; thus, an alternative 

is proposed that would be downstream of the Taunton 

urban area. Similarly, a new gage site is proposed on 

the Merrimack River, near the Haverhill/Methuen line, 

so that contaminant loads for the Merrimack River 

would include runoff from as many urban areas and 

major tributaries as possible. Two other sites are 

proposed for fixed-station monitoring that are currently 

are not gaged—the Connecticut River at Northfield, 

Mass., near the State boundary with Vermont and New 

Hampshire, and the Blackstone River at Uxbridge, 

Mass. 

The exact location of each sampling site c

changed to accommodate specific water-quality 

mation needs. For example, the proposed site o

Chicopee River at Indian Orchard, Mass., woul

exclude pollutant loads from urban runoff, com

sewer overflows, and other sources associated w

the City of Chicopee urban area, which is down

of the proposed site. Similarly, loads to the Conn

River from the Deerfield River, measured at the 

existing gage, would exclude the effects of sew

treatment facilities discharging to the Green Riv

which joins the Deerfield River downstream of 

gage. These site could be moved to capture the 

of the downstream contaminant sources. The sit

West Branch Farmington River, which is intend

represent loads from a relatively undeveloped w

shed with no point sources, also could be moved 

downstream toward the Connecticut State borde

desired. However, such water-quality informati

1 Currently sampled for water quality by the USGS National Water-Quality Assessment Program.

2 Currently sampled for water quality by USGS in cooperation with the Connecticut Department of Environmental Protection.

3 Drainage areas for the Connecticut River at Thompsonville, Conn., include drainage areas of sites on the Chicopee, Deerfield, Millers, and 

Rivers and the ungaged site on the Connecticut River at Northfield, Mass. 4 Drainage areas for the Merrimack River near Haverhill/Methuen, Mass., include drainage areas of sites on the Concord, Nashua, and Shaw

Rivers.

Table 10. Sampling sites and drainage areas for Tier II monitoring to determine loads carried by major rivers in Massa

[No., number; USGS, U.S. Geological Survey]

River and sampling location Major basin

USGS

station

No.

Drainage area, in squa

Massachusetts 

Aberjona River at Winchester, Mass.1..................................... Boston Harbor / Mystic 01102500 25 

Blackstone River at Uxbridge, Mass. ...................................... Blackstone not gaged 244 

Charles River at Watertown, Mass.1 ........................................ Charles 01104615 271 

Chicopee River at Indian Orchard, Mass................................. Chicopee 01177000 690 

Concord River at Lowell, Mass. .............................................. SuAsCo 01099500 399 

Connecticut River at Thompsonville, Conn.2 .......................... Connecticut 01184000 32,526 3

Connecticut River at Northfield, Mass. ................................... Connecticut not gaged 26 

Deerfield River at West Deerfield, Mass.................................. Deerfield 01170000 279 

French River at N. Grosvenordale, Conn.2.............................. French 01125100 95 

Housatonic River at Ashley Falls, Mass.2................................ Housatonic 01198125 422 

Ipswich River at Ipswich, Mass............................................... Ipswich and Parker 01102000 125 

Nashua River at East Pepperell, Mass. .................................... Nashua 01096500 418 

Neponset River at Milton Village, Mass.................................. Boston Harbor / Neponset 011055566 108 

Merrimack River near Haverhill/Methuen, Mass. ................... Merrimack not gaged 41,084 4

Millers River at Erving, Mass.................................................. Millers 01166500 293 

Quinebaug River at Quinebaug, Conn.2 .................................. Quinebaug 01124000 135 

Taunton River at Bridgewater, Mass........................................ Taunton not gaged 317 

West Branch Farmington River near New Boston, Mass. ....... Farmington 01185500 92 

Westfield River at Westfield, Mass. ......................................... Westfield 01183500 496 
Tier II: Fixed-Station Monitoring Program for Contaminant Loads in Major R

needs should be evaluated in the context of the 

resources required for establishing and maintaining a 

new streamflow gage to accommodate them, unless a 

nearby gage can be used to estimate streamflow at the 

sampling site. 

Sampling at the proposed sites would provide 

information to determine contaminant loads from 

67 percent of the total land area of Massachusetts 

(table 10). Unsampled areas in the proposed network 

design are primarily in Eastern Massachusetts. Many of 

the major basins in Eastern Massachusetts contain 

many, relatively small streams that discharge directly to 

the coast (fig. 7), and hydrology on Cape Cod and the 

Islands is dominated by ground-water flow. It would 

not be possible to conduct loads monitoring in these 

areas, given realistic resource limitations. One 

approach to characterizing contaminant loads from 

these areas would be to add a limited number of sites in 

small coastal watersheds that are considered representative of adjacent basins. These sites could be moved 

after sampling had been conducted for a sufficient time 

(several years) to adequately characterize contaminant 

loads on the sampled streams. For coastal streams of 

any size, alternatives to conventional stream gaging 

techniques would be needed to quantify loads from 

areas downstream from the furthest downstream gageable sites (fig. 7). Alternative approaches include 

methods for measuring flow through dams at river 

mouths or modeling and may require site-specific studies or monitoring programs. In some areas, such as near 

Boston, the downstream areas are heavily urbanized 

and contain significant sources of contaminants; thus, 

special studies may be desirable to characterize the 

water-quality conditions in these areas. 

Sampling sites also could be added to the Tier II 

network to address information needs that are regional, 

rather than statewide, in scale. For example, a site in 

the upper Charles River Basin (near Medway) would 

be useful to track the trends in constituent concentrations due to the increased development in the upper 

portions of that basin. A similar argument could be 

made for the Assabet River (near Maynard), as this 

river basin is also affected by increased development 

along the Interstate 495 corridor. Other sites include 

the Weweantic and North Rivers, which are both 

coastal streams. The Weweantic River is influenced 

by cranberry cultivation within its basin, and the 

Weweantic and North Rivers both are affected by 

increased development.

Sampling parameters for Tier II monitori

are proposed to provide information on the wat

quality issues of concern for each receiving wat

or other monitoring location. Thus, loads of nut

that stimulate eutrophication or other contamin

that impair the designated uses of receiving wat

are of interest. Loads of nutrients and suspende

sediments, which might be associated with orga

contaminants such as PCBs, also are likely to b

interest across State boundaries. Sampling for fi

parameters (temperature, specific conductance, 

and dissolved oxygen), nutrients (nitrogen and 

phorus species), bacteria, and suspended sedim

proposed for all Tier II sites. Sampling for bact

(fecal coliform and E. coli; Enterococcus, an in

for salt water, could be included for coastal site

is proposed, to provide additional, general infor

on the status of waters for the contact recreation 

Sampling for other parameters, such as selected 

or organic compounds, could be added based on 

specific information needs at some sites or prev

knowledge of impairments, for example, at site

the Massachusetts–Connecticut boundary.

Sampling frequency for Tier II monitorin

determined by the need to adequately character

the range of hydrologic and seasonal conditions 

loads calculations. Thus, about monthly sampli

frequency is needed, but samples need not be at 

regular intervals. Additional samples will likely 

needed during high- and low-flow periods to fu

cover the range of hydrologic conditions and 

characterize wet-weather conditions. This is 

particularly important for suspended sediment a

sediment-associated contaminants such as phos

and metals, because sediment concentrations ar

variable and depend on changing flow condition

Fifteen, isokinetic depth- and width-integrated s

per year at each site are initially proposed; this 

sampling frequency is consistent with the recen

redesigned USGS NASQAN sampling program 

contaminant loads on freely flowing large rivers 

(Hooper and others, 1997). The sampling frequ

could be revised after several years of data colle

and analysis, if it were determined that less freq

sampling were adequate. The sampling frequen

could be enhanced by the use of volunteers or p

local observers. Volunteer monitors would be p

larly useful for sediment and sediment-borne co

nants, because daily or more frequent (during h

flows) sampling could be needed to adequately 

tify sediment loads (Edwards and Glysson, 199
50 Statewide Water-Quality Network for Massachusetts

42005'

420

10'

710

15'

710

10'

710

05'

420

15'

0 5 MILES

0 5 KILOMETERS

EXPLANATION

RESIDENTIAL AREA

NON-RESIDENTIAL URBAN

UNDEVELOPED LAND

BASIN BOUNDARY

SUBBASIN BOUNDARY

PERENNIAL STREAMS

BACTERIA SAMPLING SITE

Figure 7. Sites sampled for bacteria for hot-spot monitoring in the 1994 Neponset water-resource assessment and 

generalized land use in the basin. Land-use data from MassGIS; undeveloped land use as shown includes a small 

amount of agricultural land use.
Tier III: Targeted Monitoring Prog

A recommended approach is that volunteers collect 

point or single-profile, depth-integrated samples, and 

statistical relations are used to relate these samples to 

the depth- and width-integrated samples collected 

by agency personnel for use in loads calculations 

(Edwards and Glysson, 1999). Continuous measurement of field turbidity, in conjunction with frequent 

samples collected by agency personnel or volunteers, 

could be used to develop relations between turbidity 

and sediment concentration that would allow for more 

accurate calculation of sediment loads (Christensen 

and others, 2000).

Resource Requirements

Resource requirements for Tier II monitoring 

were defined in terms of the personnel requirements for 

sampling collection, the laboratory analyses needed, 

and the costs for stream gaging at currently ungaged 

sites. Sampling the 19 proposed stations 15 times per 

year requires 270 site visits and samples for analysis 

annually. It is expected that 0.5 to 1 day would be 

required for each visit for one to two people, depending 

on travel distances, the proximity of sites, and the 

sampling parameters at each site. Site visits in which 

metals samples were collected would always require 

two people, to implement the low-level sampling protocols; metals sampling also would require extra fieldwork preparation time to pre-clean sampling equipment. Sampling of two or even three sites per day may 

be possible when two-person crews are used, and 

samples are taken at existing stream gages (such that 

streamflow need not be measured at the time of 

sampling). One-person crews may be appropriate for 

some sites with one visit per day. However, sampling 

large rivers typically is conducted with two-person 

crews, because it entails the use of specialized equipment that is deployed off bridges or boats and because 

of safety concerns, especially under high-flow conditions. Assuming that one-half of the stations require 0.5 

days per visit and half require 1 day for two people, 

500 personnel-days (about 2 FTEs) would be required 

for sample collection for Tier II monitoring, with some 

additional time needed for field-work preparation. The 

laboratory analyses needed for these samples would 

include 285 analyses for nutrients (total nitrogen and 

phosphorus, or separate analyses of nitrogen and 

phosphorus species) and bacteria, at least that m

analyses for suspended sediment (probably man

more), and a lesser number of analyses metals. 

The resources required for sampling the T

sites could be reduced through cooperative agre

among States. Specifically, sampling at the Quin

French, and Connecticut Rivers (Thompsonville

Conn.) currently is being conducted by the USG

Connecticut District, in cooperation with the Co

cut Department of Environmental Protection. A

tive sites on these streams in Massachusetts cou

chosen for inclusion in the Massachusetts moni

program, but a more efficient use of resources w

to share sampling costs at sites near the Connec

and Massachusetts boundary between the two S

Similarly, water-quality samples are currently b

collected at a site on the Blackstone River in M

Mass., about 3 mi downstream from the propos

Blackstone site, by the USGS in cooperation w

Rhode Island Department of Environmental Ma

ment. Because the Millville site is not suitable f

measurement, the alternative site in Uxbridge, M

was proposed. Cost-sharing between Massachu

and Rhode Island could be considered for the 

Blackstone River sampling to maximize the use 

monitoring resources and avoid redundancy in d

collection. Resources also would be required fo

lishing and maintaining new streamflow gages a

currently ungaged sites. 

TIER III: TARGETED MONITORING 

PROGRAMS 

Monitoring that targets particular location

areas, or issues is categorized in the statewide n

design as Tier III monitoring. It includes data c

tion for 303(d) listing of impaired water bodies 

required by the CWA, hot-spot monitoring, and 

site-specific investigations. Because these progr

are focused on specific issues or areas rather tha

providing more general information on the statu

waters over a wide area, their monitoring design

vary significantly based on site characteristics a

monitoring objectives.

Monitoring for 303(d) listing is conducte

on specific reaches of identified water bodies. S

monitoring could verify an impairment indicate

reconnaissance-level sampling, in order to place 

water body on the State’s 303(d) list, or confirm 
52 Statewide Water-Quality Network for Massachusetts

impairment of an already listed water body. An example of this type of monitoring is wet- and dry-weather 

sampling by the USGS and DEP/DWM for selected 

metals at a site on the Mystic River in Medford, 

between Lower Mystic Lake and the Amelia Earhardt 

Dam, a reach that is currently listed as impaired by 

toxics (Commonwealth of Massachusetts, 1999). 

Data collected for these purposes is defined by the 

water-quality problem of interest and must be of high 

quality. High-quality, well-documented data are needed 

because the monitoring results may affect the development of TMDLs for the sampled water bodies and may 

need to be legally defensible. For these reasons, professional water-quality sampling may be required for 

this type of Tier III monitoring. The highest level of 

quality control and documentation would be needed for 

volunteer monitoring data to be used. 

Monitoring of known or suspected impaired 

waters or monitoring to identify impairment sources 

is hot-spot monitoring. Hot-spot monitoring is an 

important objective of the MWI teams (A.S. Johnson 

and W.R. Dunn, Massachusetts Department of Environmental Protection, written and oral commun., 

1999). It differs from monitoring for the statewide 

305(b) assessment, which also yields information on 

impaired water bodies over a wide area, in that its focus 

is on impairments in specific streams and reaches so 

that remedial actions can be taken rather than to 

provide information on the overall status of all streams 

in the area. Hot-spot monitoring, as discussed in this 

report, also differs from the kind of systematic 

sampling program that would be required to locate 

impaired waters in a basin without any prior knowledge of their likely distribution. Hot spots are defined 

here as sources of impairments, rather than the resulting impaired or con taminated stream reaches, and 

monitoring approaches for locating such sources are 

discussed in this section. The discussion focuses on 

streams; approaches for lakes or other water bodies 

would differ based on their specific hydrologic 

regimes. As with Tier I monitoring, a review of the 

1994 MWI pilot assessment of the Neponset Basin is 

used to provide context for the discussion of hot-spot 

monitoring strategies.

In the 1994 Neponset assessment, contamination 

of surface waters by fecal bacteria was a known 

major problem throughout the basin (Kennedy and 

others, 1995). This knowledge was used to design a 

sampling program to identify sources of bacterial 

contamination in the basin. Other objectives of the 

sampling program included a basin-wide assess

existing conditions for compliance with State w

quality standards, information on occurrences o

contaminants in water, sediment, and biota, and 

biological integrity assessment of the Neponset 

and some of its major tributaries (Kennedy and 

1995, p. 1-2). It is important to consider these o

objectives because the same sampling sites wer

used for these purposes as well as for the hot-sp

monitoring.

The monitoring program for bacterial con

nation in the 1994 Neponset study used 41 sam

sites. No information is provided on the approa

criteria used for site selection (Kennedy and oth

1995). The sites are located along the mainstem

Neponset (8 sites, primarily in the upper segme

East Branch Neponset Rivers (1 site) and along 

all of their major tributaries (32 sites, along 16 

tributary streams; Halliwell and others, 1982; fi

One to four sites are located along each mainste

segment or tributary, distributed at varying poin

headwaters to mouths. Thus, the monitoring pro

appears to have used, at least in part, a geograp

based, targeted approach to distribute sites amo

streams in the basin. Other criteria, such as loca

knowledge of problem areas, also may have bee

to select streams for sampling or to locate sites 

streams, but it is not possible to infer these proc

from the information provided in the report. Mo

sites were sampled 3 times, on July 19, August 

and October 18, 1994. Several sites also were s

on December 12, 1994 (4 times total), or were s

on only one or two of the sampling dates. The J

and October sampling dates represented dry-we

conditions, whereas the August sampling date w

marginally wet weather in that it occurred 2 day

a substantial storm.

In general, the bacteria data collected in th

study were primarily used to identify and priori

impaired reaches rather than to locate specific s

of impairment. The prevalence of fecal coliform 

concentrations exceeding state standards (stand

exceeded at 30 of 41 sites) also was used to confi

finding that bacterial contamination was a majo

quality problem in the basin (Kennedy and othe

1995, p. 2-15). Sites were prioritized based on r

concentrations on a basin map. In terms of sour

tification, the elevated fecal coliform concentra

dry- as well as wet-weather samples were used 

conclude that sources in the basin were likely to 

leaking sewer lines and failed septic systems, as 
Tier III: Targeted Monitoring Prog

stormwater runoff. A specific source was identified in 

only one instance. Exceptionally high fecal coliform 

concentrations (32,000 to 224,000 colonies per 100 

milliliters) were measured in Meadow Brook (fig. 2), a 

channelized tributary to the Neponset River that drains 

the urban center of Norwood. These results led to infrastructure investigations by the Town of Norwood in the 

Meadow Brook drainage area, through which leaking 

sewer lines were identified and remedied. Specific 

sources for which remedial actions could be initiated 

were not identified for the other 29 impaired sites. The 

authors of the report recognize that additional sampling 

was needed for source identification and for monitoring 

the effectiveness of ongoing management actions 

(Kennedy and others, 1995).

The 1994 Neponset study illustrates the framework for an effective approach for hot-spot monitoring, 

but also demonstrates the potential difficulties of using 

a single monitoring design for multiple, and to some 

extent conflicting, objectives. The bacteria sampling 

sites were intended to identify reaches that were 

contaminated by bacteria as well as the sources of the 

contamination; a third objective was to provide information on the status of waters in the basin with respect 

to water-quality standards for bacteria for contact 

recreational uses [the 305(b) assessment]. The most 

effective approach to locate specific impaired reaches 

is a systematic, geographically distributed sampling 

program; such approaches have been developed for 

locating highly contaminated areas at hazardous-waste 

sites using sampling grids (Gilbert, 1987). Knowledge 

of the expected locations of the impairments allows for 

more efficient sampling, in that expected contaminated 

areas can be sampled more densely. However, for an 

assessment of existing conditions throughout a basin, 

this kind of targeted sampling is likely to lead to biased 

results, because contaminated areas are preferentially 

sampled. For the identification of impairment sources, 

a multi-purpose sampling program also may not be 

adequate because source identification usually requires 

follow-up water-quality sampling or other types of 

investigation, as with the Meadow Brook example in 

the Neponset Basin. Resources may not be allocated or 

remaining for these investigations once the overall 

sampling program is completed. 

Effective programs for hot-spot monitoring 

are based on substantial knowledge of identified or 

suspected problem areas and on site and contaminant 

characteristics. Sources of knowledge about problem 

areas are historical water-quality data, land-use data, 

and local observations or anecdotal reports of 

impairments. This information can be gathered 

MWI teams and used for site selection. Monito

data at all quality levels and the local knowledg

volunteer groups also could be very effective, fo

selection or source identification. In the tiered n

design described in this report, the probabilistic

deterministic sampling program for basin-based 

monitoring is another source of knowledge abo

lem areas. Types or causes of impairments prev

a basin and specific impaired reaches could be i

fied through the relatively extensive water-quali

sampling proposed for larger streams. For smal

streams, in which macroinvertebrate sampling (

response variable) and bacteria sampling only a

proposed, less information would be provided o

chemical or physical causes and geographic dis

tion of impairments; however, Tier I sampling i

vidual basins could be augmented with addition

water-quality parameters on these streams for r

naissance-level identification of impairment cau

Once known or suspected hot spots are id

fied, specific sampling programs could be desig

based on the sites and contaminants of concern

of the program would be to confirm existence o

problem, document its persistence and variabili

determine whether inferences as to its source ca

made from sampling results. The sampling para

and temporal and spatial scales for sampling dep

site conditions and cannot be specified in advan

Sites downstream of a known hot spot, such as 

ground-water plume discharging to a stream or 

combined-sewer overflow, may be sampled repe

over time to characterize its effect on stream qu

under varying hydrologic conditions or to docu

improvements from remedial actions. Sites at 

suspected hot spots would be similarly sampled

that less information would be available to guid

sampling program. When a suspected problem 

confirmed, a second phase of sampling may be n

in which sampling sites are chosen upstream to 

the area of maximum contamination. Existing k

edge of land uses and potential non-point and p

sources along the sampled reach and its tributar

could be used to guide the second phase of sam

The Meadow Brook site in the Neponset Basin 

example where infrastructure investigation with

additional water-quality sampling was sufficien

identify a source to the extent that remediation c

achieved. Another example, where more additio

work is needed for source identification, is an o
54 Statewide Water-Quality Network for Massachusetts

investigation in the Millers River by the USGS, DEP, 

and MWI basin team, where a several-year study with 

repeated sampling along 44 stream miles is being 

conducted to locate the source of PCB contamination 

in fish and sediments in the river. 

Because knowledge of impaired areas is an 

important basis for hot-spot monitoring, the 1994 

Neponset bacteria results also were used to investigate 

whether GIS procedures could be developed that would 

substantially aid site selection for identifying impaired 

reaches. Land-use data from MassGIS (1995 data at 

1:25,000-scale; MassGIS, 1997) were aggregated into 

generalized categories of residential, non-residential 

urban, and undeveloped uses, reflecting their expected 

contribution of bacteria to surface waters (fig. 7: the 

undeveloped land-use category, shown with agricultural land use in figure 7, did not include agricultural 

land use in the statistical analyses). Mean and median 

fecal coliform concentrations at the 41 sampling sites 

were compared with percentages of these three generalized land uses in (a) the entire watersheds of the 

sampling sites (mean and standard deviation of watershed areas equal to 9.2 +21 mi2), (b) watershed areas 

extending upstream to the watershed of the next tributary confluence or significant lake (“incremental watershed area”, mean and standard deviation equal to 0.64 

+0.65 mi2), and (c) 200-foot riverfront buffer areas 

along the streams, extending from the sampling site 

upstream to the next tributary confluence or significant 

lake (mean and standard deviation of lengths equal to 

0.58 +0.56 mi). Tributary confluences and significant 

lakes were chosen as the upstream boundaries to landuse areas used in the comparison, rather than using a 

uniform distance upstream from the sampling site, to 

minimize the effects of dilution from tributary inflows, 

variable streamflow velocities (Parker and DeSimone, 

1992), and variable attenuation from die-off, sedimentation, or other factors during transport through lakes 

(Bowie and others, 1985). Concentrations and land-use 

percentages were compared directly using the nonparametric Spearman Rank correlation test and by comparing land-use percentages between groups of sites where 

State bacteria standards for primary contact recreation 

were exceeded and not exceeded using the Mann 

Whitney test. 

If land use were found to be an indicator of fecal 

coliform contamination, the watersheds and stream 

reaches throughout the basin could have been analyzed 

in terms of land use to determine how well the siteselection scheme of the 1994 assessment sampled all 

the watersheds or stream reaches in the basin th

were likely to be impaired. However, no statisti

significant (alpha equal to 0.10) relations were 

except for a weak correlation between median f

coliform concentrations and residential land use 

incremental watershed areas of the sampling sit

importance of residential land use as a source o

ria to streams is consistent with literature report

example, Bladys and others, 1998; James and o

1998, and references therein); however, these re

did not support additional quantitative review o

1994 sampling results. 

The general lack of statistically significan

tions among land use and bacterial concentratio

found here likely results at least in part from the 

scope and available data for the analysis. Howe

also illustrates the difficulties in using land-use 

the absence of any other, local knowledge to ide

specific impaired reaches for contaminants like 

ria. Sources of bacteria, which include stormwa

runoff, leaking sanitary sewers, illicit connectio

storm sewers, combined-sewer overflows, and w

fowl (Weiskel and others, 1996), are in general 

ated with specific land uses but also are highly v

within mapped land-use categories, and in-strea

processes affecting bacteria are complex. Thus, 

of investigating the 1994 sampling program con

the central role of site-specific knowledge in the 

of hot-spot monitoring programs. 

Because hot-spot monitoring programs ar

issue-, site-, and basin-specific, the resources re

for an effective program for this component of T

of the statewide network cannot be defined in ad

As with other components of a statewide netwo

scope of hot-spot monitoring programs in basin

be defined at least in part by the resources avail

the effort. One approach would be for a regulat

agency, such as DEP/DWM, to work with group

situated to collect local and historical knowledg

as the MWI teams, to identify and prioritize pro

contaminants and problem areas in a basin for e

assessment cycle. This process could be inform

reconnaissance-level sampling by volunteer gro

and(or) by Tier I monitoring results. Resources 

could be allocated, based on the total amount o

resources available for this component of a stat

network and the relative severity of the identifie

problems among and within basins. Detailed ho

monitoring programs then could be designed th

would effectively address the specific problem 

and issues. 
Tier V: Strategies for Compliance-Based Ambient Monit

TIER V: STRATEGIES FOR 

COMPLIANCE-BASED 

AMBIENT MONITORING

Thousands of water-quality samples are 

collected annually in Massachusetts to document or 

determine compliance with regulations governing 

water quality of wastewater discharges, water 

supplies, and other municipal and private entities. 

Data collected for compliance-monitoring programs 

may be difficult to interpret in terms of ambient conditions, however, because analyses are performed on 

treated water or wastewater or on natural waters that 

are directly affected by pollutant sources. One alternative for enhancing the efficient use of limited monitoring resources is to modify compliance-monitoring 

programs to provide ambient data that supports the 

multiple water-quality information needs of 

Massachusetts. 

The National Pollutant Discharge Elimination 

System (NPDES), a permit program under the regulatory authority of the Federal CWA, is administered by 

USEPA and the States. In accordance with the CWA, 

all point-source discharges of pollutants to U.S. surface 

waters must be permitted under the NPDES program 

(U.S. Environmental Protection Agency, 1997c). A 

NPDES permit specifies the quantity and quality of 

waste or effluent that may be discharged by a permittee 

or facility to a specific water body (or “receiving 

water”). The permit generally also specifies a monitoring program that must be conducted by the permittee 

to determine that permit standards are being met. 

Typical NPDES permittees include municipal sewagetreatment facilities, which discharge treated effluent, 

and industrial facilities, which may discharge treated 

wastewater, cooling water, or stormwater; receiving 

waters may be streams or coastal waters. Permitted 

NPDES discharges also include municipal storm sewer 

systems serving populations of 100,000 or greater and 

some large construction projects (U.S. Environmental 

Protection Agency, 2000). Monitoring programs in 

NPDES permits commonly include periodic (daily, 

weekly, or monthly, for example) sampling of effluent 

at discharge locations for temperature, suspended 

solids, fecal bacteria, oil and grease, specific toxic 

pollutants (for example, metals or solvents), or nutrients; monitoring programs are tailored to specific facility operations and discharge types. Permitted NPDES 

dischargers are classified as “major” or “minor” based 

on the volume of effluent or other water discharged. 

Compliance monitoring for the NPDES p

in Massachusetts was evaluated as a potential so

ambient water-quality data by analyzing the loc

of permitted major NPDES discharges as poten

stream-quality sampling sites. Sites were analyz

terms of geographic distribution among major b

in the State, stream order of the receiving water

upstream watershed areas of sites. Stream order 

receiving water is a measure of the distribution 

among streams of varying sizes and is used to e

how well the major NPDES discharge locations 

serve for a statewide assessment of existing con

in streams, as outlined in Tier I of the monitorin

design described in this report. Information on 

upstream watershed areas of sites is useful for e

ing how well the major NPDES discharge locat

would serve as a network of sites for determina

contaminant loads, as outlined in Tier II of the m

ing design. It should be noted that the use of co

ance-monitoring sites for the collection of ambi

water-quality data for these purposes requires s

considerations, which also are discussed in this 

A preliminary data layer of permitted ma

NPDES discharges in Massachusetts was obtain

from DEP for this analysis (Brian Brodeur, 

Massachusetts Department of Environmental Pr

tion, written commun., 1999). This data layer, cu

undergoing field checking and revision, was the 

available representation of NPDES discharge lo

at a statewide scale. Some NPDES permittees w

represented by multiple point locations in the d

layer, which may have corresponded to facility 

ings, pipe outlets, or discharge lagoons. Discha

were identified by the NPDES permit number, f

name, facility type (for example, municipal or i

trial), and receiving water of the discharge. The 

layer contained 205 discharge locations, which 

associated with 155 permitted discharges to sur

waters across the Commonwealth.

The preliminary NPDES data layer was m

by replacing multiple discharge locations with a 

point feature for each discharge permit that was 

on the receiving-water stream as represented by 

MassGIS digital hydrography (1:25,000-scale c

line data) For discharge permits represented by 

point in the preliminary data layer, this point fe

also was moved to the receiving stream where n

sary. These modifications were not made, howe

for discharge locations in brackish water, estuar

coastal waters, where centerline locations could 
56 Statewide Water-Quality Network for Massachusetts

determined, or for discharge locations in basins for 

which centerline data layers were not currently available. Centerline data layers were not available for the 

North Coastal and Buzzards Bay basins; a preliminary 

version of the centerline data layer for the Taunton 

basin was obtained from MassGIS and was used in this 

and other NPDES-related analyses. The modified 

NPDES data layer is shown in figure 8. 

Strahler stream order of discharge-location sites 

was determined in ARC/INFO on a basin-by-basin 

basis, for all basins except the North Coastal and 

Buzzards Bay basins. Stream-order definitions in this 

analysis were based on both perennial and intermittent 

streams, because elimination of intermittent streams 

from each basin’s centerline data layer would have 

required detailed GIS editing that was beyond the 

scope of this analysis. In addition, watershed areas 

of sites were delineated in ARC/VIEW using the 

MassGIS Data Viewer’s Watershed Analyst (MassGIS, 

2000a, 2000b) for all sites except those located in the 

North Coastal, Buzzards Bay, and Taunton basins, 

where the Watershed Analyst was not available at the 

time of the analysis. 

Major NPDES discharge locations are distributed throughout the State, although the density of sites 

generally is greater in eastern basins than in western 

basins (table 11 and fig. 8). Several basins, including 

the Cape Cod and Islands, Farmington, Shawsheen, 

and Westfield basins, have few or no discharge locations to streams. As might be expected, the discharge 

locations are disproportionately located on large 

streams. Sixty-two percent of all locations (79 percent 

of sites for which stream order was determined) are on 

fourth-order or larger streams; these streams are likely 

to account for only about 20 percent of the total perennial stream miles in the state, based on analysis of the 

Neponset Basin (table 4). Only 7 percent of discharge 

sites (9 percent of sites for which stream order was 

determined) are located on first-order streams, which 

accounted for nearly half of the perennial streams in 

the Neponset Basin.

A sampling network that used major NPDES 

discharge sites for a statewide assessment of existing 

conditions in streams for 305(b) and similar purposes 

would be based on a targeted or deterministic monitoring approach. Because site selection is deterministic 

rather than probabilistic, conditions in the sampled 

streams could not be readily extrapolated to unsampled 

streams with an NPDES-based network. Thus, 100 percent coverage of stream miles in the state would not be 

possible. An estimate of the coverage potentiall

vided by sampling at major NPDES sites can be 

by making assumptions about the lengths of str

represented by samples at the discharge sites, th

about stream reaches adjacent to the sites that w

expected to have relatively homogeneous water 

and biological integrity. Assuming lengths of 3 

miles per site for first- through third-order strea

5 mi per site for fourth-order and larger streams

of 553 stream miles, or less than 10 percent of t

perennial stream miles in the state, could be ass

The majority (86 percent) of these stream miles 

be fourth-order and larger streams, such that a s

wide assessment based on NPDES sites alone w

biased towards larger streams. Sampling at NPD

sites could be combined with other parts of a Ti

monitoring design to increase the overall covera

provided by the deterministic components of a 

design. However, sites provided by the NPDES 

work may not be optimum for several reasons, 

discussed further below.

The distribution of major NPDES dischar

might be more appropriate for a network with o

tives of determining contaminant loads (Tier II 

tives), rather than for a statewide status assessm

The total watershed areas of NPDES sites in ba

where watersheds could be delineated (123 site

excluding sites in the Buzzards Bay, North Coa

and Taunton basins) is 5,062 mi2, which is a lar

fraction (72 percent, excluding areas of the three 

listed above) of the total land area of Massachu

Many of the NPDES sites are located on the ma

rivers that would be of interest for contaminant 

although the sites are unlikely to be at the speci

locations (river mouths or State boundaries) of 

in most cases. Where discharge sites were well l

sampling could occur upstream of the discharge 

location(s) for ambient loads or water-quality, o

and downstream if data also were needed to cha

ize the discharge’s effect on stream quality, for 

ple, as part of a TMDL program. Samples at 

downstream locations also could be used to ide

the need for increased treatment or upgrades at 

discharging facility (D.R. Dunn, Massachusetts 

Department of Environmental Protection, writte

commun., 2000). Potential sites for each facility 

need to be evaluated by an experienced water-q

professional to identify locations suitable for sa

and flow measurement with respect to streamflo

point source(s), in-stream mixing, and other fac
Tier V: Strategies for Compliance-Based Ambient Monitoring 57

0 10 20 30 40 50 KILOMETERS

0 10 20 30 40 50 MILES

CAPE COD 

BAY

ATLANTIC OCEAN

BUZZARDS BAY

MASSACHUSETTS BAY

IPSWICH BAY

NANTUCKET

SOUND

42 ̊00'

42 ̊30'

7300

7230' 72 ̊00' 71 ̊30'

70 ̊00'

41 ̊30'

WATERSHED-DRAINAGE AREAS OF SITES 

 (AREAS INSIDE OF MASSACHUSETTS ONLY)

BOUNDARY OF MAJOR BASINS AND THEIR NAMES

BOUNDARY OF WATERSHED-DRAINAGE AREA OF NPDES SITE,

WHERE NOT COINCIDENT WITH MAJOR BASIN BOUNDARY

NPDES DISCHARGE SITE

EXPLANATION

Map source: USGS, MA-RI District GIS coverages

BLACKSTONE

NASHUA

SUASCO

SHAWSHEEN

PARKER

IPSWICH

BOSTON 

HARBOR

BOSTON HARBOR

CHARLES

SOUTH COASTAL

CAPE COD

ISLANDS

BUZZARDS BAY

TAUNTON

NARRAGANSETT 

BAY

TEN 

MILE

HUDSON

HOUSATONIC

DEERFIELD

WESTFIELD

FARMINGTON

CONNECTICUT

MILLERS

CHICOPEE

FRENCH HUDSON

NORTH COASTAL

MERRIMACK

ISLANDS

QUINEBAUG

QUINEBAUG

FRENCH

RHODE ISLAND

NEW HAMPSHIRE

CONNECTICUT

VERMONT

NEW YORK

Figure 8. Locations and watershed-drainage areas of permitted major discharge sites within the National Pollutant Discharge Elimination System (NPDES) in 

Massachusetts for potential water-quality monitoring. Discharge sites in the Buzzards Bay and North Coastal Basins and sites discharging to coastal waters may be 

represented by more than one discharge location; drainage areas in the Buzzards Bay, North Coastal, and Taunton Basins are not shown.
58 Statewide Water-Quality Network for Massachusetts

suitable sampling sites might not be available for some 

discharge sites. Continuous flow data are needed to 

calculate contaminant loads; thus, if flow measurements could not be made at or near the site, or if the 

site were not close enough to a streamflow gage such 

that intermittent measurements could be related to a 

continuous record, loads could not be determined. In 

addition, isokinetic depth- and width-integrated sampling would likely be needed, which in general is best 

implemented by experienced water-quality personnel. 

More generally, sampling and analyses by facility personnel or contractors may result in data that are 

sufficient comparability or quality to meet infor

needs. Well-defined protocols for sample collec

handling, and analysis, including perhaps the u

one or a small number of laboratories for all an

and rigorous quality control procedures would b

needed. Even with these requirements, data col

by multiple, private entities may not be compar

among sites or over time at individual sites or b

sufficient quality such that contaminant loads c

be calculated at all sampling sites.

Table 11. Distribution of major discharge sites within the National Pollutant Discharge Elimination System among majo

basins and stream orders in Massachusetts

[Density of discharge sites: Based on basin areas within Massachusetts; --, no sites or not determined]

Major basin

Number of discharge sites Den

dis

sites

per 

Stream order Coastal sites or other 

sites for which 

stream order was not 

determined

Total

1 2 3 4 5 6–7

Blackstone ........................................... -- 3 2 1 5 1 -- 12 0

Boston Harbor (Mystic, Neponset, 

Weymouth, and Weir) ...................... 1 -- -- -- 1 -- 13 15 

Buzzards Bay....................................... -- -- -- -- -- -- 9 9 

Cape Cod and Islands .......................... -- -- -- -- -- -- 1 1 

Charles ................................................ -- -- -- 2 2 1 -- 5 

Chicopee .............................................. 1 1 -- -- -- 3 -- 5 

Connecticut.......................................... 1 -- 1 1 4 8 -- 15 

Deerfield .............................................. -- -- 1 2 1 -- 4 

Farmington........................................... -- -- -- -- -- -- -- -- 

French .................................................. -- -- -- -- 1 -- -- 1 

Housatonic........................................... -- -- -- 2 6 -- -- 8 

Hudson................................................. -- -- -- 1 1 -- -- 2 

Ipswich ................................................ 1 1 -- 1 -- -- -- 3 

Merrimack ........................................... 1 1 -- 1 -- 6 1 10 

Millers.................................................. -- -- -- 3 -- 6 -- 9 

Narragansett and Mt. Hope Bay .......... -- -- -- -- -- -- 2 2 

Nashua ................................................. -- -- 1 -- 4 3 -- 8 

North Coastal....................................... -- -- -- -- -- -- 10 10 

Parker................................................... -- -- -- -- -- -- -- -- 

Quinebaug............................................ -- -- 1 1 -- 1 -- 3 

Shawsheen ........................................... -- -- -- -- -- -- -- -- 

South Coastal....................................... 2 -- -- -- -- -- 2 4 

SuAsCo (Assabet, Concord, and 

Sudbury) .......................................... 3 1 -- 2 3 1 -- 10 

Taunton ................................................ 1 -- 2 3 2 1 4 13 

Ten Mile............................................... -- -- -- -- -- -- 3 3 

Westfield .............................................. -- -- -- -- 3 -- -- 3 

TOTAL.............................................. 11 7 8 20 32 32 45 155 0
Summary and Conclus

SUMMARY AND CONCLUSIONS

A water-quality monitoring program is proposed 

that would provide data to meet multiple information 

needs of Massachusetts agencies and others concerned 

with the quality of the State’s water resources. The 

program design was guided by the information needs 

of the Massachusetts Department of Environmental 

Protection, Division of Watershed Management 

(DEP/DWM), which include mandates of the Clean 

Water Act (CWA) and Massachusetts Watershed Initiative (MWI) activities, and by input from many organizations involved in water-quality monitoring in the 

State. The program has several components or tiers, 

which are defined in terms of specific monitoring 

objectives, and is focused on inland surface waters. The 

objective of Tier I of the monitoring program is to provide a periodic assessment of the water-quality status 

of the State’s surface and ground waters, as is required 

by section 305(b) of the CWA. The objective of Tier II 

is to determine loads of contaminants carried by major 

rivers in Massachusetts at strategic locations, such as 

at the mouths of major rivers and at State boundaries. 

Targeted monitoring programs for various objectives, 

such as the listing of impaired water bodies required 

by section 303(d) of the CWA, the identification of 

causes and sources of impairment for 303(d) and 

305(b) purposes, and hot-spot monitoring for pollution 

source identification, compose Tier III of the statewide 

monitoring program. A fourth monitoring Tier is 

needed for the development of Total Maximum Daily 

Loads for specific impaired waters, but is not described 

in this report. Monitoring for compliance with regulations and permits, such as the National Pollutant 

Discharge Elimination System (NPDES) permits, is 

a possible fifth tier that might be modified to provide 

ambient water-quality data as well as compliance data. 

To guide development of the monitoring program design, a review was conducted of general 

principles of network design, including monitoring 

objectives and approaches, and of ongoing monitoring 

activities of Massachusetts state agencies. A clear definition of objectives for the monitoring program is a 

first and necessary step in network design. Monitoring 

approaches, which comprise the details of how waterquality measurements will be made, are chosen to 

answer the water-quality questions posed by the 

program objectives. Monitoring approaches can be 

defined in terms of the time period of the measurements (short-term, long-term, or rotating), the method 

of site selection (targeted or probabilistic), the t

measurements made (for example, physical, che

or biological), the type of water resource being 

tored (for example, stream, lake, or ground wat

the use of the monitoring results. Monitoring m

include fixed-station monitoring, which is a typ

monitoring in which the same sites are repeated

sampled at regular time intervals for a long peri

time. Fixed-station monitoring and flow data ty

are needed to estimate mass fluxes or constituen

as in Tier II of the proposed monitoring program

not the best approach for a large-scale assessme

water-resource conditions, as is needed for Tier 

proposed program. Short-term (synoptic) surve

incorporate probabilistic designs are more appr

for large-scale assessments. 

Ongoing monitoring programs by State a

include (1) lake sampling, fish-toxics monitorin

measurements of benthic macroinvertebrates, an

water-chemistry monitoring by DEP/DWM, (2) 

monitoring by DEM in State parks, (3) reservoi

reservoir tributary, and coastal river sampling fo

bacteria and water-chemistry by the Metropolit

District Commission and the Massachusetts Wa

Resources Authority, (4) bacteria and physical m

ing in coastal waters by the Division of Marine 

ies and fish community surveys by the Division 

Fisheries and Wildlife of the Department of Fis

Wildlife, and Environmental Law Enforcement

ground-water monitoring for highway-runoff co

nants by the Massachusetts Highway Departme

(6) diverse monitoring activities of many local v

teer groups. Many of these activities would pro

useful data for components of the statewide mon

program, but none has the monitoring approach

geographic coverage, sampling density, or samp

parameters that would provide information to m

the information needs of DEP/DWM, the MWI 

and USEPA. The review of ongoing monitoring 

grams demonstrates the need for the developme

a statewide monitoring program such as the one 

described in this report. 

The proposed monitoring program develo

for Tier I objectives consists of a basin-based as

ment of existing surface-water-quality condition

respect to State water-quality standards and the 

nated uses of water bodies. Requirements for a 

program that reflects CWA mandates, are that it 

statewide in scale, comprehensive (all water bo

in the State are assessed), and repeated at regul
60 Statewide Water-Quality Network for Massachusetts

intervals. Another goal is improvement in the 305(b) 

assessment, through an increase in the number of 

stream miles and lake acres assessed and a reduction in 

the historical bias toward problem areas. Several 

approaches for this tier and their associated resource 

requirements were considered. Information collected 

in the Neponset Basin in Eastern Massachusetts, 

which was used as a pilot area for the MWI in the 

early 1990s, was used in the investigation of these 

approaches. GIS-based procedures were developed to 

inventory streams and lakes in the basin for a comprehensive assessment. Resources required for an exhaustive approach, in which every stream segment and lake 

in the basin is assessed and data are collected to evaluate nearly all applicable water-quality standards, were 

estimated to be about 2,660 personnel-days or 12 fulltime equivalents (FTEs) for field sample collection and 

processing and about 4,700 laboratory analyses. These 

estimates are for the Neponset Basin alone, which has 

less than one-half of one of the average area of the 27 

major basins (300 mi2) and less than one-third of the 

average area of the basin areas assessed by the MWI 

teams (400 mi2). Thus, for statewide implementation, 

in which five major basins are assessed per year, perhaps 10 times the Neponset estimates would be needed, 

or about 120 FTEs for sample collection and processing and about 47,000 analyses; in all likelihood, more 

than double the personnel resources would be needed 

when project planning, field preparation, data management and analysis, and other aspects of the program are 

included. Thus, resource requirements for a comprehensive assessment of all water bodies using this 

exhaustive approach are much greater than could be 

realistically expended. 

During the 1994 MWI pilot assessment of the 

basin, about one-half of the total stream miles were 

assessed for their designated uses, with a sampling 

density that was considerably less than that proposed 

for a systematic, exhaustive assessment of streams and 

lakes in the basin. All fourth- and fifth-order were 

assessed for most designated uses; the fraction of thirdorder streams assessed varied from 15 to 85 percent, by 

use; and less than one-half of second-order streams and 

less than one-third of first-order streams were assessed 

for any use. About one- to three-fourths of significant 

(larger than 5 acres) lakes in the basin were assessed 

for designated uses; lake assessments were based on 

limited data that resulted in impairment only being 

assessed for important uses of aquatic life and primary 

contact recreation. Analysis of the Neponset Basin and 

of the MWI pilot demonstrated that resource-lim

problems will always be posed by the large num

of sites needed in order for all the small stream

basin to be sampled (about half of stream miles 

Neponset Basin were headwater or first-order s

and the need for repeated site visits to assess so

uses. Thus, a monitoring program is proposed in 

(a) probabilistic monitoring of small streams is 

bined with the deterministic or targeted monito

large streams and (b) deterministic or probabili

monitoring of lakes may be supplemented with 

intensive sampling in lakes of special interest. S

streams, including first-, second-, and third-ord

streams, are assessed probabilistically for the aq

life and recreational uses. Depending on the res

expended, comprehensive estimates of these us

small streams could be made on a state-wide ba

or for individual basins also. For large streams, 

ing fourth-, fifth, and some third-order streams, 

all designated uses would be assessed. Lakes la

than 10 acres are assessed for aquatic life use an

trophic status. 

The combined probabilistic-deterministic 

gram would provide information to meet CWA 

ments and provide data for other information ne

Massachusetts regulatory agencies and MWI te

would be implemented on schedule with the 5-y

rotating-basin cycle of the MWI, probably in th

MWI’s research and assessment years. Manage

level decisions would be needed with respect to 

gram objectives and sampling density for the pr

listic component of the program, about whether 

estimates of use support for small streams are n

on the statewide scale only or for individual bas

also. With the statewide estimate for small strea

only, about 30 FTEs for field sample collection 

processing and about 10,500 laboratory analyse

be needed; this assumes that five basins, each o

requires about twice the effort as the Neponset, 

assessed per year. Additional time for field prep

and data management could double these requir

to about 60 FTEs, with several additional FTEs 

for program administration, planning, site selec

and obtaining permissions. Although they are m

less than the requirements for the exhaustive ap

these resource requirements are substantial. The

be reduced by eliminating or reducing assessme

some designated uses that require intensive sam
Summary and Conclus

such as the recreational use for small streams or frequent sampling of lakes for trophic status, or by using 

a probabilistic approach for lakes. 

Volunteer monitoring could be used in several 

ways to enhance the proposed program for Tier I monitoring or to offset the resource requirements for field 

data collection. Volunteer monitoring, coordinated 

through the MWI teams, could be used to conduct 

biomonitoring or collect bacteria samples at additional 

sites in basins where individual status estimates for 

small streams are needed; these estimates could be less 

rigorous if less sophisticated biomonitoring protocols 

were followed by the volunteer groups than by agency 

personnel. Volunteer monitoring of additional sites on 

large streams could be used to increase the number of 

third-order streams that are deterministically monitored 

or to increase the sampling density on mainstem 

reaches, most likely for aquatic life (water chemistry 

sampling) or recreational (bacteria sampling) uses. For 

lakes, volunteer monitoring could be used to increase 

or maintain the measurement frequency for trophicstatus indicators, to conduct more intensive assessments for some lakes, or to sample lakes of special 

interest deterministically if a probabilistic approach for 

lakes generally is taken. 

For Tier II, a fixed-station sampling network to 

determine contaminant loads carried by major rivers, 

a total of 19 sampling sites are proposed. The sites 

are located primarily at or near existing streamflow 

gages in 17 of the 27 major basins in Massachusetts. 

Sampling at these sites would provide information on 

contaminant loads from 67 percent of the total land 

area of the State. The remaining unsampled areas of the 

State would be primarily coastal areas, which are 

drained by many small streams. Resource limitations 

would preclude including all these streams in a loads 

network. A limited number of sites in small coastal 

watersheds also could be sampled for a sufficient time 

(several years) to characterize loads from the watersheds, however, then discontinued and relocated elsewhere in the coastal area. Loads from some areas 

between the coast and the inland limit of tidal influence 

will not be determinable without developing sitespecific, non-standard methods for flow measurement 

(through dams, for example), or modelling. Resource 

requirements for Tier II of the network were estimated 

at about 2 FTEs for water-quality sample collection, 

with additional time needed for field preparation, data 

analysis and resources for the management, and 

installation, operation, and maintenance of any 

streamflow gages. 

Targeted programs of Tier III of the prop

network are described primarily in terms of stra

for hot-spot monitoring, that is, monitoring to i

pollution sources. These strategies are investiga

using an analysis of the bacteria sampling progr

the 1994 Neponset Basin assessment. In that stu

data from 41 sites were used to identify leaking 

lines and failed septic systems, as well as storm

runoff, as general sources of bacteria contamina

the basin and to confirm that bacteria were a ba

wide problem. The bacteria source for a specifi

impaired reach was identified in only one instan

of 29 impairments, using infrastructure investig

by a town rather than by additional water-qualit

sampling. An analysis of watershed areas of the 

sampling sites found little relation between bac

concentrations and land uses expected to be bac

sources. These analyses illustrate the difficultie

can arise when a single monitoring design is us

to address multiple, sometimes partly conflictin

monitoring objectives. They also demonstrated 

effective programs for hot-spot monitoring are 

on substantial knowledge of suspected problem 

and on site and contaminant characteristics, inf

tion that commonly is compiled by MWI teams 

also could be provided to some extent by Tier I 

monitoring program. Approaches for hot-spot m

ing programs, in terms of sampling parameters 

density, require site-specific development and re

requirements that cannot be defined in advance

Finally, the distribution of major Nationa

Pollutant Discharge Elimination System (NPDE

in Massachusetts was evaluated to determine th

fulness of these sites for the collection of ambie

water-quality data. Locations of 155 sites were 

reviewed. The sites were well distributed geogr

cally among basins, but were located primarily o

rivers, with two-thirds or more on fourth- or hig

order streams. Use of these sites for a statewide 

ment of stream-water quality, such as needed fo

of the monitoring program, would yield estimat

use support that were biased towards large stream

targeted approach to site selection also would m

that monitoring could not be extrapolated to uns

streams. With assumptions of 3 mi of assessed 

per site for first- through third-order streams an

per site for fourth- and higher order streams, a t
62 Statewide Water-Quality Network for Massachusetts

553 mi, or less than 10 percent of the perennial stream 

miles in the State, would be assessed by sampling 

major NPDES sites. NPDES sites might be more suited 

to sampling for loads or Tier II objectives than for a 

statewide status assessment. Watersheds of major 

NPDES sites, where they could be determined, account 

for about 70 percent of the total land area of Massachusetts. These sites may not be optimally located in terms 

of the loads objectives, however; they also would 

require review and perhaps sampling by experienced 

water-quality personnel. It might also be difficult to 

design and implement sampling protocols for use by 

multiple private entities to ensure adequate data quality 

and comparability.

In summary, the water-quality monitoring 

program described in this report contains several 

components that would provide information to meet 

many of the water-quality information needs of the 

Massachusetts state agencies and others concerned 

about water resources in the State. The components are 

complementary in many ways but are not interchangeable, and each component requires a substantial investment of personnel time, laboratory analyses, and other 

resources. Several components must be developed on 

site-specific bases, and available resources will place 

important constraints on all aspects of the program. 

The water-quality information needs to which components of the proposed program are addressed must be 

carefully evaluated and prioritized, so that monitoring 

resources are efficiently and effectively deployed in 

accordance with the critical tasks of protecting and 

managing the water resources of Massachusetts. 

REFERENCES

Ackerman, M.T., 1989, Compilation of lakes, ponds, 

reservoirs and impoundments relative to the 

Massachusetts Clean Lakes Program: Westborough, 

Mass., Massachusetts Department of Environmental 

Quality Engineering, Division of Water Pollution 

Control, TSB.

Ackerman, M.T., Batiuk, R.A., and Beaudoin, T.M., 

1984, Compilation of lakes, ponds, reservoirs and 

impoundments relative to the Massachusetts Lake 

Classification Program: Boston, Mass., Massachusetts 

Department of Environmental Quality Engineering, 

Publication number 13786-216-30-8-84-CR, 196 p.

Bladys, Stanley, III, Raines, T.H., Mansfield, B.L., a

Sandlin, J.T., 1998, Urban stormwater quality, 

mean concentrations, and estimates of stormwa

pollutant loads, Dallas-Fort Worth Area, Texas, 

1992–93: U.S. Geological Survey Water-Resou

Investigations Report 98-4158, 51 p.

Bowie, G.L., Mills, W.B., Porcella, D.B., Campbell, 

Pagenkopf, J.R., Rupp, G.L., Johnson, K.M., C

P.W.H., Gherini, S.A., and Chamberlin, C.E., 1

Rates, constants, and kinetics formulations in s

water quality modeling (2d ed.): Athens, Ga., U

Environmental Protection Agency, Office of Re

and Development, EPA/600/3-85/040, 455 p.

Carlson, R.E., 1977, A trophic state index for lakes: 

Limnology and Oceanography, v. 22, p. 361–36

Christensen, V.G., Jien, Xiaodong, and Ziegler, A.C

Regression analysis and real-time water-quality 

monitoring to estimate constituent concentratio

loads, and yields in the Little Arkansas River, S

Central Kansas, 1995–99: U.S. Geological Surv

Water-Resources Investigations Report 00-4126

Commonwealth of Massachusetts, 1997, Summary o

quality 1996: Worcester, Mass., Commonwealt

Massachusetts, Executive Office of Environmen

Affairs, Department of Environmental Protectio

Division of Watershed Management, 135 p.

_____1998, Summary of water quality 1998: Worce

Mass., Commonwealth of Massachusetts, Exec

Office of Environmental Affairs, Department of 

Environmental Protection, Division of Watersh

Management, 145 p.

_____1999, Final Massachusetts section 303(d) list 

waters: Worcester, Mass., Commonwealth of 

Massachusetts, Executive Office of Environmen

Affairs, Department of Environmental Protectio

Division of Watershed Management, 131 p.

Cuffney, T.F., Gurtz, M.E., and Meador, M.R., 1993

Methods for collecting benthic invertebrate sam

part of the National Water-Quality Assessment 

Program: U.S. Geological Survey Open-File Re

403, 66 p.

Dates, G., Dickens, S., and Tremblay, M., 2000, Vol

monitoring program development: Report to th

Massachusetts Executive Office of Environmen

Affairs, Oct. 13, 2000, variously paginated.

Edwards, T.K., and Glysson, G.D., 1999, Field meth

measurement of fluvial sediment: U.S. Geologi

Survey Techniques of Water-Resources Investig

Book 3, Ch. C2, 89 p.

Gilbert, R.O., 1987, Statistical Methods for Environ

Pollution Monitoring: New York, Van Nostrand 

Reinhold Company, 319 p.
Refere

Gordon, N.D., McMahon, T.A., Finlayson, B.L., 1992, 

Stream hydrology—An introduction for ecologists: 

New York, John Wiley and Sons, 526 p.

Halliwell, D.B., Kimball, W.A., and Screpetis, A.J., 1982, 

Massachusetts stream classification program: Part I: 

Inventory of rivers and streams: Westborough, Mass., 

Massachusetts Department of Environmental Quality 

Engineering, Division of Water Pollution Control, 

Technical Services Branch, 125 p., and associated 

documentation.

Helsel, D.R., and Hirsch, R.M., 1992, Statistical Methods in 

Water Resources: Amsterdam, The Netherlands, 

Elsevier Science Publishing Company, 522 p.

Hooper, R.P., Goolsby, D.A., Rickert, D.A., and McKenzie, 

S.W., 1997, NASQAN, Monitoring the water quality of 

the Nation’s large rivers, A river-basin perspective on 

monitoring water quality: U.S. Geological Survey Fact 

sheet FS-055-97, 6 p.

Intergovernmental Task Force on Monitoring Water Quality, 

1995a, The strategy for improving water-quality 

monitoring in the United States--Final report of the 

Intergovernmental Task Force of Monitoring Water 

Quality: U.S. Geological Survey Open-File Report 95-

742, accessed February 24, 2000 at URL 

http://water.usgs.gov/wicp/lopez.main.html. 

_____1995b, The strategy for improving water-quality 

monitoring in the United States—Technical 

Appendixes--Final report of the Intergovernmental Task 

Force of Monitoring Water Quality: Reston, Va., U.S. 

Geological Survey, 117 p.

James, William, Huber, W.C., Dickinson, R.E., and James, 

W.R.C., eds, 1998, Water Systems Models Hydrology, 

Users Guide to SWMM4 RUNOFF and supporting 

modules: Guelph, Ontario, Canada, CHI and University 

of Guelph, 283 p. 

Kennedy, L.E., O’Shea, L.K., Dunn, Jr., W.J., and LeVangie, 

D., 1995, The Neponset River Watershed 1994 resource 

assessment report: North Grafton and Boston, Mass., 

Massachusetts Department of Environmental 

Protection, Office of Watershed Management, variously 

paginated.

Kentucky Division of Water, 1997, Kentucky Watershed 

Management Framework Document: accessed May 19, 

2000, at http://water.nr.state.ky.us/dow/wa/default.htm.

Lopes, T.J., and Price, C.V., 1997, Study plan for urban 

stream indicator sites of the National Water-Quality 

Assessment Program: U.S. Geological Survey Openfile Report 97-25, 15 p.

Massachusetts Department of Environmental Protection, 

1997, About the Bureau of Resource Protection: 

accessed February 11, 2000, at URL 

http://www.state.ma.us/dep/brp/aboutbrp.htm.

MassGIS, 1997, MassGIS Datalayer descriptions an

to user services: Boston, Mass., Massachusetts 

Executive Office of Environmental Affairs, Ma

1997, 131 p.

_____2000a, MassGIS Data Viewer Overview, Marc

2000: accessed June 19, 2000, at URL

http:// www.magnet.state.ma.us/mgis/vwrover.h

_____2000b, MassGIS Data Viewer Watershed Ana

March 2000: accessed June 19, 2000, at URL 

http://www.magnet.state.ma.us/mgis/vwr_wa1.

Parker, G.W., and DeSimone, L.A., 1992, Estimatin

reaeration coefficients for low-slope streams in 

Massachusetts and New York, 1985–88: U.S. 

Geological Survey Water-Resources Investigati

Report 91-4188, 34 p. 

Parker, G.W., and Gay, F.B., 1987, Equation to estim

reaeration coefficients in Massachusetts stream

Geological Survey Water-Resources Investigati

Report 86-4111, 34 p.

Persaud, D., Jaagumagi, R., and Hayton, A., 1993, 

Guidelines for the protection and management 

aquatic sediment quality in Ontario: Ontario, C

Queen’s Printer for Ontario, Ontario Ministry o

Environment, Water Resources Branch.

Roth, N.E., Chaillou, J.C., and Gaughan, Michael, 1

Guide to using 1995 Maryland biological stream 

data: prepared by Versar, Inc., Columbia, Md., 

Maryland Department of Natural Resources, An

Md., May 1997, variously paginated

Roth, N.E., Southerland, M.T., Chaillou, J.C., Volsta

Weisberg, S.B., Wilson, H.T., Heimbuch, D.G., 

Seibel, J.C., 1997b, Maryland biological stream 

ecological status of non-tidal streams in six bas

sampled in 1995: prepared by Versar, Inc., Colu

Md., for Maryland Department of Natural Reso

Annapolis, Md., May 1997, variously paginated

Sanders, T.G., Ward, R.C., Loftis, J.C., Steele, T.D., 

D.D., and Yevjevick, Vujica, 1987, Design of N

for Monitoring Water Quality: Littleton, Colora

Water Resource Publications, 328 p.

Scheaffer, R.L., and McClave, J.T., 1982, Statistics f

Engineers: Boston, Duxbury Press, 475 p.

Smith, R.A., Alexander, R.B., and Wolman, M.G., 1

Analysis and interpretation of water-quality tre

major U.S. rivers, 1974–81: U.S. Geological Su

Water-Supply Paper 2307, 25 p.

U.S. Environmental Protection Agency, 1997a, Guid

for preparation of comprehensive state water-qu

assessments (305(b) reports) and electronic upd

report contents: Washington, D.C., U.S. Enviro

Protection Agency, Office of Water, EPA-841-B

002A, variously paginated.
64 Statewide Water-Quality Network for Massachusetts

U.S. Environmental Protection Agency, 1997b, Guidelines 

for preparation of comprehensive state water-quality 

assessments (305(b) reports) and electronic updates: 

supplement: Washington, D.C., U.S. Environmental 

Protection Agency, Office of Water, EPA-841-B-97-

002B, variously paginated.

_____1997c, NPDES Permit Program—General 

Information: U.S. Environmental Protection Agency, 

Office of Wastewater Management, accessed April 24, 

2000, at URL http://www.epa.gov/owm/gen2.htm.

_____1998a, Envirofacts Warehouse, 1998, accessed 

November and December 1998, at URL 

http://www.epa.gov/9966/envirodcd/owa) .

_____1998b, Lake and reservoir bioassessment and 

biocritera, Technical Guidance Document: U.S. 

Environmental Protection Agency, Office of Water, 

EPA-841-B-98-007, variously paginated.

_____1999, Summary of state biological assessment 

programs for streams and rivers: U.S. Environmental 

Protection Agency, Office of Water, EPA230-R-96-007, 

accessed February 11, 2000, at URL 

http://www.epa/gov/owow/monitoring/bio.

_____2000, About the NPDES storm water program: U.S. 

Environmental Protection Agency, Office of Wastewater 

Management, accessed April 24, 2000, at URL

http://www.epa.gov/owm/sw/about/index.htm.

U.S. Geological Survey, 2000, Water resources of N

Hampshire and Vermont, Study design of the N

England Coastal Basins and preliminary monit

plans, accessed November 9, 2000, at URL 

http://nh.water.usgs.gov/CurrentProjects/nawqa

web2.htm.

Weiskel, P.K., Howes, B.L., and Heufelder, G.R., 19

Coliform contamination of a coastal embaymen

sources and transport pathways: Environmental 

and Technology, v. 30, no. 6, p. 1872-1881.

Waldron, M.C., Steeves., P.A., and Finn, J.T., 2001, 

thematic mapper imagery to assess water qualit

trophic state, and macrophyte distributions in 

Massachusetts lakes: U.S. Geological Survey W

Resources Investigations Report 01-4016, 40 p

Ward, R.C., Loftis, J.C., and McBride, G.B., 1990, D

water quality monitoring systems: New York, V

Nostrand Reinhold, 231 p.

Wood, Pamla, Shipp, Alison, and Colten, Lee, 1999

2000 Strategic monitoring plan, Salt & Licking 

Management Unit, Kentucky: accessed May 19

at URL http://water.nr.state.ky.us/dow/mon2.ht
APPENDIX—Geographic Information System (GIS)

and other computer-based procedures used in the

monitoring design for the Neponset Basin

Appe

GENERAL COMMENTS

The procedures outlined below describe the steps that can be followed to inventory 

streams and lakes in a basin as needed for the Tier I network design of the proposed statewide monitoring program. The inventory for streams involves segmenting the streams at 

tributary confluences, intersections with lakes, and point-source discharges. Digital data 

used in these procedures is the 1:25,000-scale hydrography made available with the 

MassGIS Watershed Data Viewer (MassGIS, 2000a). Most of the procedures are carried 

out using ESRI’s ARC/INFO Geographic Information System (GIS) software or the 

Watershed Viewer, which is run in ESRI’s ARCVIEW software. Knowledge of and facility 

with these software packages is assumed in the steps described.

An overview of the procedures is as follows:

A. First, the centerline stream data layer for the basin was edited, in ARC/INFO, to 

generate a data layer of points that define the boundaries between stream segments 

and downstream of lakes. The approach used to complete this task was guided by 

the need to delineate watersheds for each stream segment and lake included in the 

inventory (these were needed for a stratified-sampling design based on watershed 

characteristics, which was not in fact implemented in the final monitoring design). 

Consequently, streams were segmented in ARC/INFO at locations that were at 

small distances (30 meters) upstream from the actual points of tributary 

confluences and of intersections with lake boundaries, so that separate watersheds 

could be accurately delineated for each segment with the Watershed Analyst. 

B. The data layer of points defining stream-segment boundaries was used to create 

“events” along the centerline hydrography for the basin using the Watershed 

Analyst in ARCVIEW. Events are points along a stream network that are 

referenced to the network in terms of distance along a stream reach and 

upstream/downstream order. Unique identification numbers were given to the 

stream segments, and an event table was created that provided information on the 

distance of each point along its reach. These data were later manipulated in a 

spreadsheet to determine individual stream segment lengths (see item 4, below).

C. Watersheds, which were saved as ARCVIEW shape files, were delineated from 

each event. These represent watersheds for all stream segments and lakes in the 

basin. The application within the Watershed Analyst that was used to delineate 

watersheds from a point-event table (that is, in batch mode), rather than 

interactively and individually, were specifically created for this project by Aleda 

Freeman at MassGIS.

D. Stream segment data from (B) were manipulated in a spreadsheet to generate 

population statistics such as total stream miles in the basin, length per segment, 

and so on. 
68 Statewide Water-Quality Network for Massachusetts

1. SEGMENTATION OF STREAM HYDROGRAPHY IN THE NEPONSET BASIN 

USING ARC/INFO

1.1. PREPARATION OF THE STREAM COVERAGE

1.1.1. Copy the centerline coverage (called “centerline”) for the basin of 

interest out of the “watershed” library of the MassGIS Watershed 

Data Viewer. This is the coverage created by MassGIS that represents 

hydrography as a routed network.

1.1.2. Remove all arcs that do not connect to the main network (these arcs 

represent streams that flow into sink holes such as a kettle pond).

1.1.3. Drop the node, route, and section feature classes from the centerline 

coverage using 'Dropfeatures'.

1.1.4. Build the centerline coverage as a polygon coverage to complement 

the line attributes that still exist. The purpose of this step is to allow 

identification of braided areas in the centerline coverage.

1.1.5. Review the polygons that exist in the centerline coverage. There 

should be two types of polygons, which will be separately handled:

- Large polygons are typically stream networks that share the same 

headwaters (generally a wetland). These areas are left as is.

- Small polygons are typically areas inside a braided stream. 

Identify these areas on a plot; these areas will need special 

manipulation in a subsequent step (1.2.13b, below)

1.1.6. Drop the polygon feature class. The edited centerline coverage that 

results will be a line coverage containing only connected streams. 

1.2. SEGMENTING STREAMS BASED ON TRIBUTARY CONFLUENCES

1.2.1. Make a copy of the edited centerline coverage. Retain both copies; 

continue steps described below on one copy. 

1.2.2. Remove intermittent streams. Save them in a separate coverage. 

1.2.3. Drop the line feature class; then re-build the coverage as lines. 

Calculate the attribute “covername-id” equal to 1 for all lines. 

1.2.4. Remove pseudo nodes using the 'Eliminate' command. 

1.2.5. Remove any dangling arcs with lengths less than 100 meters 

(328 feet). Save them in a separate coverage.

1.2.6. Run the 'Eliminate' command again to remove pseudo nodes left over 

after the removal of dangling arcs less than 100 meters (there may be 

a few pseudo nodes remaining on very long arcs). 

1.2.7. Build the coverage as nodes. Add two items to the node attribute 

table (NAT) using the ‘Additem’ command: NODE_TYPE (4 5 B) 

and NODE_CODE (2 2 I). 

1.2.8. Create a coverage of all lakes and ponds in the watershed by selecting 

them out of the hydrography coverage (“hydro”) that is located in the 

“watershed” library. The hydrography coverage is the traditional 

1:25,000-scale digital data representing hydrography as shown on 

USGS topographic quadrangles. The lake coverage created in this 

step will be used to identify confluences in the centerline coverage 

that occur within lakes (step 1.2.9, below).
Appe

1.2.9. Calculate values for NODE_TYPE and NODE_CODE as follows:

NODE_TYPE: 1 = dangles; 2 = pseudo nodes; 3 = all remaining 

nodes (nodes of type 3 will be at the tributary confluences). 

NODE_CODE: 

1 = pseudo nodes (same as node_type = 2)

2 = nodes at confluences within lakes (Use the 'Overlap' option of 

the ‘Reselect’ command in ArcPlot, with the coverage of lakes 

created in step 1.2.8, above, as the overlap coverage.)

3 = dangles (same as node_type = 1 except for the node at the 

mouth of the network).

4 = dangles in lakes (Repeat the ‘Reselect/Overlap’ procedures 

with the lakes coverage for NODE_CODE = 2, then reselect for 

NODE_TYPE = 1. These nodes are uniquely identified because

they are headwater nodes.)

5 = node at mouth of basin

8 = all remaining nodes (confluences). These nodes will be used in 

step 2.1.4, below, to define stream segments. 

1.2.10. Run the 'Buffer' command on the nodes, using 30 meters as the buffer 

distance, to create circular polygons of 30-meter radii around all 

nodes. 

1.2.11. Reselect all nodes with a NODE_CODE = 8. Within this selected 

set, reselect all buffers which overlap the selected nodes (Use the 

‘Reselect’ command in ARC/PLOT), using the coverage created in 

step 1.2.10 (“coverbuff”) as the buffer coverage and the coverage 

being developed (“coverage”) as the input coverage, as follows ‘Reselect coverbuff poly overlap coverage node’). Create a new coverage of 

the selected buffer polygons, using the ‘Writeselect’ command. 

1.2.12. Run the 'Identity' command using the edited centerline coverage as 

the input coverage and the coverage of buffer polygons as the identity 

coverage (use 'LINE' for feature class). This is done to create nodes 

where the buffer boundary intersects the centerline. 

1.2.13. Select all new nodes created in step 1.2.12 (NODE_CODE = 0) and 

calculate NODE_CODE = 99. Quality-assure these nodes on the 

computer screen by “zooming into” various areas in the map. 

Check for two problems: 

a. Areas where there are multiple river sections (for example, 

canals, mud flats, or marshland). In these areas, select 

nodes that may overlap one another or cluster. Keep 

some representative nodes for these areas, coded as 

NODE_CODE = 99. Calculate the remainder to 

NODE_CODE = 6. 

 b. Nodes that are on braided-stream sections (identified and plotted in step 1.1.5; these areas include cranberry bogs). Calculate 

NODE_CODE = 7 for these. 
70 Statewide Water-Quality Network for Massachusetts

1.2.14. Run the 'Nodepoint' command to create points from the nodes in 

the coverage. In the output point coverage, select all points with 

NODE_CODE values not equal to 99 and delete them. The remaining 

points are the population for defining stream segments by tributary 

confluences. 

1.3. INVENTORYING LAKES AND SEGMENTING STREAM 

HYDROGRAPHY BASED ON LAKES:

1.3.1. Preparation of the lakes coverage

1.3.1.1. From the coverage of lakes created in step (1.2.8), above, 

create a new coverage by reselecting all polygons larger 

than 5 acres (20,235 square meters). NOTE: This coverage,

of lakes larger than 5 acres, is the coverage used as an 

inventory of lakes in the basin for the monitoring program.

1.3.1.2. Check that all lake polygons lie on the centerline network of 

perennial and intermittent streams. Do this by comparing the 

coverage of lakes larger than 5 acres with the edited centerline coverage retained in step 1.2.1 that included intermittent 

streams. In rare instances, lakes may not lie on the centerline 

network, and may need special handling to delineate their 

watersheds (see step 3, below).

1.3.1.3. Review the lakes polygons in the coverages on screen to 

identify single lake bodies that are represented by two adjacent polygons. These may occur at quadrangle boundaries 

(for example, Bird Pond in the Neponset Basin) or where 

lakes are partly coded as lake/open water and partly as 

lake/wetland. Review these lakes on the topo quadrangles 

and dissolve the internal arcs as appropriate. This step also 

may be completed in step 2.1.2.2.

1.3.2. Build the edited centerline coverage with intermittent streams, 

retained in step (1.2.1), above, as a node coverage (complimenting 

the line feature class). Add an item to the node attribute table, 

LAKE_NODE (1 1 I). Calculate all nodes to LAKE_NODE = 1.

1.3.3. 'Clip' the centerline data later using the coverage of lakes larger than 

5 acres as the clip coverage, specifying ‘Line’ for the feature class 

option. 

1.3.4. New nodes will be created from this clip. Reselect all nodes where 

LAKE_NODE = 0 and calculate LAKE_NODE = 2 for these new 

nodes.

1.3.5. Run the 'Buffer' command on the coverage using ‘Node’ as the feature type and 30 meters as the buffer distance. Check the output coverage for overlapping buffer-zone polygons. Overlapping buffer 

polygons would occur in areas where two lakes, less than 60 meters 

apart, are connected by a stream. Document these areas for a 

subsequent step.
Appe

1.3.6. Reselect (in ARC/PLOT) all nodes from the clipped coverage with a 

LAKE_NODE = 2, then reselect all polygons from the buffer zones 

coverage that overlap the selected set. Create a new coverage of these 

buffer zones using the ‘Writeselect’ command.

1.3.7. Prepare the final line coverage created in the section 1.2, above, for 

inclusion of lake nodes by adding the intermittent stream segments 

and small arc lengths, which were removed in steps 1.2.2 and 1.2.5, to 

the coverage with the 'Append’ command. Select all nodes where 

NODE_CODE = 0 (these are new nodes produced during the append 

procedure), and calculate NODE_CODE = 9 for these nodes. The 

intermittent stream segments and small arc segments are added back 

to the coverage being developed at this stage, to allow for nodes to be 

determined for lakes that lie on these stream reaches. 

Note that items in both the arc (AAT) and node (NAT attribute tables 

must match before running 'Append'. If they do not match, “dummy” 

items will need to be added to the coverage that lacks attributes 

present in the other coverage. This is necessary because items in the 

two coverages must be identical to the ‘Append’ command to work 

correctly; if items are not identical, items present in one coverage and 

not in the other will be eliminated when the ‘Append’ command is 

run. The only non-default items that it is important to retain are 

NODE_TYPE and NODE_CODE items in the NAT. Build the output 

coverage from the Append procedure as LINE and NODE feature 

classes (check to see if all items exist in the NAT). 

1.3.8. Run the 'Identity' command using the final line coverage created in 

step 1.3.7, and the output coverage of buffer polygons created in 

step 1.3.6. 

In the output coverage from the ‘Identity’ procedure, reselect the 

nodes that overlap the coverage of lakes larger than 5 acres. Within 

this selected set, reselect the nodes with NODE_CODE = 0. Calculate 

the NODE_CODE = 10 for this subset of nodes. Then, use the 'Nselect' to “flop” the selected set, which will select all remaining nodes 

with NODE_CODE = 0 (these will be all nodes that are more than 

30 meters outside of lake boundaries). Calculate NODE_CODE = 98 

for these nodes.

1.3.9. Run the 'Nodepoint' command. In the output point coverage, select 

out all points with NODE_CODE values not equal to 98 and delete 

these nodes. The remaining points are the population for defining 

stream segments by significant lakes. 

1.3.10. Combine the coverage of points created in step (3.9) with lakes with 

the coverage of points created in (2) with tributary confluences, using 

the ‘Append’ command. 

Check for:

 a. Points that fall within estuaries for coastal watersheds (the 

centerline extends out to the ocean). Delete these points.
72 Statewide Water-Quality Network for Massachusetts

 b. Locations where lakes are very close to confluences. Any points 

that fall closer than 20 meters to the lake or the confluence 

should be deleted. This will occur only infrequently. 

A quick on-screen review or check plot of the coverage should 

be sufficient to locate these occurrences (nodes lying close to 

one another also can be found using the reach codes of the 

Watershed Analyst).

 c. Locations where two lakes are very close to one another identified in step 3.5). Add a point in the middle of the two lakes as 

close to the centerline as possible.

1.4. SEGMENTING STREAM HYDROGRAPHY BASED ON POINT 

SOURCES

1.4.1. Create or use an existing point coverage of the point-source sites in 

the watershed. Review the coverage for accuracy and compare it to 

the centerline coverage of streams. If a site does not lie on the centerline network, determine its correct location and move the point to that 

location. 

1.4.2. Run the ‘Nodepoint’ command and calculate NODE_CODE = 97 for 

all points. 

1.4.3. ‘Append’ the point coverage created in step 1.4.2 for NPDES locations to the point coverage based on lakes and confluences created in 

step 1.3.10. Check for match among attributes in the two coverages as 

described in step 1.3.7.

1.5. CREATING THE FINAL POINT COVERAGE OF SEGMENT 

BOUNDARIES

1.5.1. Add an attribute “ID” to the point coverage created in step 1.4.3. Calculate ID equal to the coverage# attribute; this will define a unique 

identification number for each node.

1.5.2. Run the 'Addxy' command on the point coverage. The coverage now 

is ready to create events on the centerline hydrography with the 

Watershed Analyst.

2. DETEMINING UPSTREAM/DOWNSTREAM ORDER AND ANCILLARY 

INFORMATION FOR STREAM SEGMENTS BY CREATING POINT EVENTS 

ON THE CENTERLINE HYDROGRAPHY USING ARCVIEW AND THE 

WATERSHED ANALYST

2.1. Open the MassGIS Data Viewer project in ARCVIEW. Load the extension 

'Spatial Analyst', followed by the extension 'MassGIS Watershed Delineator'.

2.2. Preset a tolerances option, using options under the 'MassGIS-Hydro' menu:

“Change snap tolerance for finding route”—This tolerance sets the maximum 

distance from which a point will snap to the centerline network. Because the 

points are already on the centerline network, this tolerance can be set at 1. 

2.3. Add the centerline theme for the basin of interest and the point coverage finalized in step 1.5.2 to the view. With both themes active, run the 'MassGISHydro' menu option 'Make point event table from coverage' to create a point 

event table. This option prompts the user to select the attribute that should be 
Appe

used to number the events. The attribute “ID,” created in step 1.5.1, was used 

to set the event identification number (ID), ensuring a unique ID for each 

event.

The point event table created in this step will provide the following information: the ID of the point event, the MassGIS reach code for the stream reach on 

which the event is located, and the distance along that reach (measured from 

its downstream end) to the event. This information will be used in step 5, 

below, to determine stream segment lengths.

2.4. Run the 'Display event table' from the 'MassGIS-Hydro' menu, which creates a 

theme and displays the point events.

3. DELINEATE WATERSHEDS FOR STREAM SEGMENTS AND LAKES USING 

ARCVIEW AND THE WATERSHED ANALYST

3.1. Open the MassGIS Data Viewer project in ARCVIEW. Load the extension 

'Spatial Analyst', followed by the extension 'MassGIS Watershed Delineator.'

3.2. Preset a tolerances option, using options under the 'MassGIS-Hydro' menu:

“Change snap tolerance for delineation”—This tolerance sets a search distance from the cell of elevation grid in the Watershed Analyst that is selected 

(in this case, the cell that the event lies within) to the lowest cell within the tolerance distance to start the delineation (the watershed delineation will start 

from this cell). Because the centerline network was used to create the events 

used for delineation, the events lie directly upon the centerline network. This 

allows snap tolerances for watershed delineation to be set at very low values. 

Low snap tolerances are especially important at confluences, where a snap tolerance greater than 2 elevation-grid cells could result in the wrong confluence 

being chosen as the starting point for the delineated watershed. However, 

although the events all are on the stream centerline, the selected elevation-grid 

cell corresponding to an event will not always correspond to the cell where the 

stream lies, as described by the grid elevations (although the stream locations 

based on the centerline and on the grid elevations should be close, due to 

enhancement processing of the source DEMs for the elevation grid). Thus, 

some leeway should be allowed for this tolerance. Because the confluence 

events are located 30 meters from the actual confluences, 15 to 20 meters is an 

appropriate value for this tolerance.

3.3. With the centerline theme and the event theme active, select the “Upstream 

Watershed for Points in Batch Mode” tool, which is a button on the Watershed 

Analyst pull down indicated with a “W” and three diamond shaped symbols 

(for more information on how to use the Watershed Analyst, see the MassGIS 

Home page: http://www.magnet.state.ma.us/mgis/.

3.4. The user is asked several questions before the batch processing begins, including whether to use either an input attribute to name the output watershed shape 

files (each watershed is output to a separate shape file) or a default value. For 

this project, the identification number determined as the coverage attribute 

“ID” in step 1.5.1 and used as the point event ID in step 2.1.3 was used. The 

user also is asked to choose attributes for inclusion in each output shape file. 

The following attributes were included: the ID of the point event, the distance 

or “measure” along the stream route that the point event occurs, measured 
74 Statewide Water-Quality Network for Massachusetts

from the beginning of the route, and the area, in square meters, of the delineated watershed. The ID and measure attributes are are important to include, 

because they maintain a relationship between the output watershed and both 

the event and the centerline network. (The ID and measure attributes also 

occur in the point event table.)

3.5. Delineated watersheds should be quality-assured with on-screen review. For 

the Neponset Basin work, 95 percent of the watersheds were found to be accurately delineated. Inaccurate delineations occurred in a few instances where, 

for example, an event was too close to an upstream lake, and the delineated 

watershed incorrectly cut partly across the lake surface instead of running outside of the lake boundary (enhancements to the watershed delineation application have been proposed to correct this problem). Because of these few 

inaccuracies, the quality-assurance review is recommended. 

3.6. If lakes larger than 5 acres include any lake not on the centerline, their watersheds will need to be separately delineated. Procedures for this will depend of 

the specific circumstances of each lake.

4. MANIPULALATION OF STREAM SEGMENT DATA TO OBTAIN STREAM 

AND LAKE POPULATION STATISTICS IN A SPREADSHEET

GENERAL COMMENT: The spreadsheet steps described below were developed 

simultaneously with the GIS procedures described in steps 1 through 3, above. The 

procedures described effectively process the data generated by the GIS work to 

obtain the information needed for the Neponset network design and analysis; however, they do not represent the most efficient approach to obtaining this information. 

The GIS procedures described in steps 1-3 result in the definition of segments along 

the centerline hydrography that can be uniquely identified by their downstream endpoints (IDs). The centerline segments include (i) segments along streams between 

confluences (“internal stream segments”) and (ii) segments extending through lakes 

(lake segments). The centerline segments also include (iii) 40-meter segments along 

mainstem reaches that extend up- and downstream from confluences with tributaries, 

and (iv) 20-meter segments along each tributary extending upstream from its confluence a higher order or mainstem stream. Segment types (iii) and (iv) resulted because 

of the need to divide the centerline hydrography small distances up- and downstream 

from confluences, rather than at their exact locations, so that watersheds could be 

delineated. Similarly, lake segments extend about 20 meters up- and(or) downstream 

from the lake inlet and outlet, respectively (separate nodes at the lake boundaries 

themselves were not created). The confluence segments and the 20-meter lengths 

within lake segments represent parts of the physical stream segments of interest for 

the stream population inventory, and their lengths must be “added back” to the internal stream segments to obtain true lengths of physical stream segments in the basin. 

The re-accumulation of stream segments for the stream population inventory from 

confluence segments and parts of lake segments was accomplished through the 

spreadsheet steps described below. A more efficient approach would be to complete 

this work within ARCVIEW. An application within the Watershed Analyst could be 

developed that would make use of the option to “Create a linear event table from the 

point event table” in the Watershed Analyst. Input to the application would be point 

events that were located at confluences and at lake inlets and outlets, rather than at 

the up- and downstream points needed for watershed delineation. A linear event table 
Appe

summarizes the length of river meters from an event to the next downstream event, 

and includes the upstream point event ID for each linear event. The linear event 

table would efficiently produce the information on stream-segment length and 

upstream/downstream order needed for an accurate stream population inventory in 

a basin. Work was begun on this application by USGS and MassGIS, but was not 

completed as part of the current project.

4.1. STREAMS

4.1.1. A spreadsheet was constructed containing:

a. event ID

b. reach code - the number MassGIS uses to uniquely code each 

continuous length of stream in the centerline coverage 

c. measure - the distance, in meters, along the reach from its 

beginning to the location of the event)

d. NODE_TYPE - S, stream; L, lake defined based 

e. order - strahler stream order 

f. watershed area

Items a, b, c, and f were obtained from the ARCVIEW shape files 

containing the watershed delineations; they also could have been 

derived from the point event table. Items d and e were obtained from 

the ARC/INFO coverage by listing attribute items NODE_TYPE and 

ORDER 

4.1.2. Data were sorted on (1) reach code and (2) measure, in ascending 

order. In this way, the centerline segments are ordered sequentially 

from downstream to upstream along a reach. 

4.1.3. Values for lengths of all centerline segments (LENGTH1), in meters, 

were determined by subtracting the measure of the upstream event ID 

from the measure of the event ID for the segment of interest. 

4.1.4. Centerline segments representing confluence segments (types iii and 

iv, above), were identified, by their lengths (about 20 or 40 meters) 

and relative positions between longer segments. The identification of 

these segments was checked on a plot of centerline hydrography and 

event locations.

4.1.5. Final values for lengths of inventoried stream segments were 

determined:

 a. For internal stream segments bounded by confluence segments, 

lengths were determined by adding the lengths of the internal 

stream segments to the length of the adjacent confluence segments (or one-half of the lengths of an adjacent confluence 

segments that extended across the confluences). 

 b. For internal stream segments bounded by lake segments, lengths 

were determined by adding 20 meters to the length of the 

internal stream segments. 

4.1.6. Final values for lengths of inventoried lake segments also were determined, subtracting 20 meters from the initial length value (step 4.1.3) 

for lake inlet and outlet segments; these procedures were verified as 

appropriate by reviewing a plot to the centerline hydrography, lake 
76 Statewide Water-Quality Network for Massachusetts

polygons, and event locations. However, this information, on length 

of the centerline hydrography as intersected by the lake boundary, 

was not used for in the current network design or analysis for 

characterizing lakes in the basin. 

4.1.7. Final values for inventoried, physical stream and lake segments of 

length, stream order, and watershed area, were output to a second 

spreadsheet for calculation of summary statistics and further analysis.

4.1.8. For lakes, values of lake area, determined by listing the AREA 

attribute of the coverage of lakes greater than five acres created in step 

1.3.1, were added to the spreadsheet created in step 4.1.7.

4.2. LAKES

4.2.1. A spreadsheet was constructed by copying items listed in step 4.1.1 

for all IDs where NODE_TYPE was equal to L (for lake).

4.2.2. Lake areas (polygon areas) were added, by matching ARC/INFO 

polygon IDs, obtained from the.PAT file of the coverage of lakes 

larger than 5 acres.

4.2.3. Lake polygons and IDs were reviewed on a plot to identify lakes represented by two polygons in the coverage. Generally, these occurred 

when part of the lake was represented by open water and part by 

wetland. These were combined in the spreadsheet inventory as 

appropriate. Note that as similar review occurred at step 1.1.1.3