Prepared in cooperation with the Michigan Department of Environmental Quality

Temporal Trends in Water-Quality Constituent Concentrations 

and Annual Loads of Chemical Constituents in Michigan 

Watersheds, 1998–2013

Scientific Investigations Report 2017–5147

U.S. Department of the Interior

U.S. Geological Survey
Cover. Saginaw River near Bay City upstream from U.S. Geological Survey station 04157065. 

Photograph by Aaron Toth.
Temporal Trends in Water-Quality 

Constituent Concentrations and Annual 

Loads of Chemical Constituents in 

Michigan Watersheds, 1998–2013

By Christopher J. Hoard, Lisa Reynolds Fogarty, and Joseph W. Duris

Prepared in cooperation with the Michigan Department of Environmental Quality

Scientific Investigations Report 2017–5147

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

RYAN K. ZINKE, Secretary

U.S. Geological Survey

William H. Werkheiser, Deputy Director

exercising the authority of the Director

U.S. Geological Survey, Reston, Virginia: 2018

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Suggested citation:

Hoard, C.J., Fogarty, L.R., and Duris, J.W., 2018, Temporal trends in water-quality constituent concentrations and 

annual loads of chemical constituents in Michigan watersheds, 1998–2013: U.S. Geological Survey Scientific Investigations Report 2017–5147, 79 p., https://doi.org/10.3133/sir20175147. 

ISSN 2328-031X (print)

ISSN 2328-0328 (online)
iii

Contents

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Water Chemistry Monitoring Program..............................................................................................3

Previous Studies and Data..................................................................................................................3

Purpose and Scope ..............................................................................................................................3

Approach.........................................................................................................................................................5

Monitoring Program Design................................................................................................................5

Sample Collection.................................................................................................................................5

Quality Assurance Samples................................................................................................................5

Water-Quality Trend Analysis .............................................................................................................7

Estimating Constituent Loads ...........................................................................................................10

Water-Quality Trend Results ......................................................................................................................10

Trends in Chloride and Total Suspended Solids ............................................................................10

Trends in Nutrient Constituents........................................................................................................13

Trends in Trace Metals Concentrations..........................................................................................17

Trend Summary ...................................................................................................................................21

Constituent Load Results............................................................................................................................21

Annual Loads and Yields for Chloride, Total Suspended Solids, and Total Phosphorus.........22

Annual Loads of Trace Metals..........................................................................................................27

Comparison of Upper and Lower Watershed Yields..............................................................................27

Summary........................................................................................................................................................31

References Cited .........................................................................................................................................31

Appendixes 1–2............................................................................................................................................35

Figures

1. Map showing Michigan watersheds and associated land cover studied as part of

the Michigan Water Chemistry Monitoring Program .............................................................2

2. Maps showing trend results for chloride, total suspended solids, total phosphorus,

and orthophosphate by Michigan watershed........................................................................15

3. Maps showing trend results for ammonia, nitrate, nitrite, and total Kjeldahl nitrogen

by Michigan watershed.............................................................................................................18

4. Maps showing trend results for chromium, copper, lead, and mercury by Michigan

watershed ....................................................................................................................................20

5. Graph showing number of upward and downward trends at Michigan stream

stations .........................................................................................................................................22

6. Graphs showing annual total phosphorus loads and yields for six intensively 

monitored rivers, 2002–13..........................................................................................................23
iv

7. Graphs showing annual total suspended solids and yields for six intensively 

monitored rivers, 2002–13..........................................................................................................24

8. Graphs showing annual chloride loads and yields for six intensively monitored 

rivers, 2002–13.............................................................................................................................25

9 Graph showing annual average streamflow for six intensively monitored rivers,

2002–13 .........................................................................................................................................26

10. Graph showing comparison of chloride, total suspended solids, and total phosphorus 

yields for lower and upper watershed sampling locations .................................................30

Tables

1. Stations sampled as part of the Michigan Water Chemistry Monitoring Program...........4

2. Michigan Water Chemistry Monitoring Program distribution of samples over time

by station, 1998–2013....................................................................................................................6

3. Summary of quality control field blank samples collected for the Water Chemistry

Monitoring Program.....................................................................................................................7

4. Summary of quality control replicate samples for the Water Chemistry Monitoring

Program..........................................................................................................................................8

5 U.S. Geological Survey station information and years for which annual loads were

produced ......................................................................................................................................11

6. U.S. Geological Survey stations used in the Water Chemistry Monitoring Program

load computation ........................................................................................................................12

7. Composite summary of constituent concentration data collected for the Water

Chemistry Monitoring Program 1998–2013.............................................................................13

8 Trend results for chloride and total suspended solids at Michigan stream stations,

1999–2013 .....................................................................................................................................14

9. Trend results for select nutrient constituents at Michigan stream stations, 

1999–2013 .....................................................................................................................................16

10. Trend results for trace metal constituents at Michigan stream stations, 

1999–2013 .....................................................................................................................................19

11. Water Chemistry Monitoring Program load and yield summary statistics for

chloride, total suspended solids, and total phosphorus at intensively monitored

stations, 2002–13.........................................................................................................................28

12. Water Chemistry Monitoring Program load and yield summary statistics for cooper, 

chromium, lead, and mercury at intensively monitored stations, 2002–13 .......................29

Appendix Tables

1. Summary of data collected at select Michigan Water-Chemistry Monitoring 

Program stream sites, 1999–2013.............................................................................................36

 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year..............60
v

Conversion Factors

International System of Units to U.S. customary units

Multiply By To obtain

Length

meter (m) 3.281 foot (ft)

Area

square kilometer (km2) 0.3861 square mile (mi2)

Volume

liter (L) 33.81402 ounce, fluid (fl. oz)

liter (L) 2.113 pint (pt)

liter (L) 1.057 quart (qt)

liter (L) 0.2642 gallon (gal)

Flow rate

cubic meter per second (m3/s) 35.31 cubic foot per second (ft3/s)

Mass

kilogram (kg) 2.205 pound, avoirdupois (lb)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

 °F = (1.8 × °C) + 32.

U.S. customary units to International System of Units

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

Area

square mile (mi2) 2.590 square kilometer (km2) 

Volume

ounce, fluid (fl. oz) 0.02957 liter (L) 

pint (pt) 0.4732 liter (L) 

quart (qt) 0.9464 liter (L) 

gallon (gal) 3.785 liter (L) 

Flow rate

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

Mass

pound, avoirdupois (lb) 0.4536 kilogram (kg) 

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows: 

 °C = (°F − 32) / 1.8.
vi

Supplemental Information

Concentrations of chemical constituents in water are given in either 

milligrams per liter (mg/L), micrograms per liter (μg/L), or nanograms per liter 

(ng/L).

Abbreviations

MDEQ Michigan Department of Environmental Quality

TKN total Kjeldahl nitrogen

TSS total suspended solids

USGS U.S. Geological Survey

WCMP Water Chemistry Monitoring Program
Temporal Trends in Water-Quality Constituent 

Concentrations and Annual Loads of Chemical 

Constituents in Michigan Watersheds, 1998–2013

By Christopher J. Hoard, Lisa R. Fogarty, and Joseph W. Duris

Abstract

In 1998, the Michigan Department of Environmental 

Quality and the U.S. Geological Survey began the Water 

Chemistry Monitoring Program for select streams in the State 

of Michigan. Objectives of this program were to provide 

assistance with (1) statewide water-quality assessments, (2) 

the National Pollutant Discharge Elimination System permitting process, and (3) water-resource management decisions. 

As part of this program, water-quality data collected from 

1998 to 2013 were analyzed to identify potential trends for 

select constituents that were sampled. Sixteen water-quality 

constituents were analyzed at 32 stations throughout Michigan. Trend analysis on the various water-quality data was 

done using either the uncensored Seasonal Kendall test or 

through Tobit regression. In total, 79 trends were detected in 

the constituents analyzed for 32 river stations sampled for 

the study period—53 downward trends and 26 upward trends 

were detected. The most prevalent trend detected throughout 

the State was for ammonia, with 11 downward trends and 1 

upward trend estimated.

In addition to trends, constituent loads were estimated for 

31 stations from 2002 to 2013 for stations that were sampled 

12 times per year. Loads were computed using the Autobeale 

load computation program, which used the Beale ratio estimator approach to estimate an annual load. Constituent loads 

were the largest in large watershed streams with the highest 

annual flows such as the Saginaw and Grand Rivers. Likewise, 

constituent loads were the smallest in smaller tributaries that 

were sampled as part of this program such as the Boardman 

and Thunder Bay Rivers.

Introduction

The surface water in Michigan and the surrounding Great 

Lakes is an important ecological, recreational, and economical 

resource. Michigan has 36,350 miles of rivers and streams that 

drain 62 major watersheds to the Great Lakes. The importance 

of these waters to the State of Michigan and Great Lakes 

was acknowledged in 1998, with the passage of the Clean 

Michigan Initiative by the citizens of Michigan. This initiative 

authorized $675 million in State bonds to finance environmental and natural resources protection programs. 

Beginning in 1998, the U.S. Geological Survey (USGS) 

Michigan Water Science Center, in cooperation with the 

Michigan Department of Environmental Quality (MDEQ), 

collected samples for water quality from tributaries throughout 

Michigan (fig. 1) as part of the MDEQ Water Chemistry Monitoring Program (WCMP). Supported by the Clean Michigan 

Initiative, this long-term monitoring program was designed to 

assess the quality of Michigan rivers and streams that drain to 

the Great Lakes and to determine if the chemical characteristics of surface waters of the State are changing with time.

The WCMP used a two-phase approach. Initially, the 

WCMP helped to establish baseline water quality for rivers 

and streams. Once baseline water quality was established, 

continued monitoring allowed for the assessment of trends 

of water-quality constituents. This type of monitoring program can help identify the need for remediation or changes in 

management practices and also help determine the effects that 

changes to prior water or land-management practices have had 

on water quality. Changes in water quality of a river or stream 

can be the result of several factors; for example, land-use 

change, population growth, water use, and climate change.

As part of the WCMP, sampling for determination of constituent loads followed the same two-phase sampling approach 

as was used to identify trends. The product of a constituent 

concentration and the volume of water during a defined period 

of time is referred to as the load of the constituent. Constituent 

loads are often estimated on an annual or monthly basis and 

are important when determining the potential impact constituents may have on the environment. Understanding constituent 

loads is important when evaluating the potential ecological 

and biological impacts to receiving waters and, ultimately, to 

the Great Lakes. For example, an intense focus has been on 

understanding the total load of phosphorus to Lake Erie (not 

shown), which has had harmful algal blooms of increasing 

frequency, magnitude, and duration since the middle 1990s 

(International Joint Commission, 2014). The total load of 

phosphorus to Lake Erie has been identified as one of the 
2 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents

18

2

30

11

15

10

19

14

13

5

1

25

31

27 24

20

12

16

17

8

3

21

26

6

23

22

7

4

9

29

28

32

Land use

Integrator

Intensive

EXPLANATION

Water

Urban

Undeveloped

Agriculture

Watershed boundary

and number

0 60 120 MILES

0 60 120 KILOMETERS

Station location

Base modified from the Michigan GIS open data portal, 2017, Watershed Boundary Dataset, 2017, 

and National Land Cover Database 2011 Land Cover (2011 Edition, amended Homer and others, 2015)

1:3,656,279, World Geodetic System, 1984

1

N

Figure 1. Michigan watersheds and associated land cover studied as part of the Michigan Water Chemistry Monitoring Program.
Introduction 3

major driving forces of the ecological transition of Lake Erie 

to this harmful eutrophic state (International Joint Commission, 2014). The overall mass of total phosphorus and nitrogen 

also has been implicated in causing large areas of hypoxia 

(dangerously low dissolved oxygen) in Lake Erie, which has 

ecological and economic consequences for the commercial 

fishery in Lake Erie’s central basin (International Joint Commission, 2014). 

By developing an understanding of the load of a constituent, in addition to evaluating the flow and seasonally normalized trends in a constituent, scientists are able to derive an 

understanding of which constituents might be driven more 

by point sources (those loads that are constant regardless of 

changes in streamflow) with those that might be more driven 

by nonpoint sources. 

Water Chemistry Monitoring Program

In 1998, the MDEQ began monitoring 27 watersheds in 

Michigan as part of the WCMP (fig. 1). The program used the 

MDEQ watershed-management units and 5-year rotational 

cycle developed by the MDEQ Ambient Surface WCMP 

(Michigan Department of Environmental Quality, 2001) to 

assess Michigan streams and channels connecting the Great 

Lakes and bays. The objectives of the WCMP were to provide assistance with (1) statewide water-quality assessments, 

(2) the National Pollutant Discharge Elimination System 

permitting process, and (3) water-resource-management 

decisions. 

The areas selected for monitoring coincide with USGS 

eight-digit hydrologic units throughout the State. Sampling 

locations in these hydrologic units were selected near the 

mouth of major streams that drain to the Great Lakes to determine the quality of the water directly entering the Great Lake 

into which each river drained. Land use in the watersheds 

differed from primarily undeveloped forest in the northern part 

of the State to more developed urban centers in the southern 

part of the State (fig. 1). Land-use categories differing from 

urban to undeveloped were represented by six hydrologic units 

that were monitored every year. Different land-use categories 

also were represented by 21 other hydrologic units that were 

monitored through 26 sampling stations (table 1). 

Previous Studies and Data

Since 2001, several reports summarizing the WCMP 

data for the State of Michigan have been published by the 

MDEQ (Michigan Department of Environmental Quality, 

2001, 2002, 2003, 2004, 2005, 2006a, 2008, 2013). Previously published WCMP reports summarizing annual and 

5-year results are available from the MDEQ, Water Resources 

Division, Water Chemistry web page at http://www.michigan.

gov/deq/0,4561,7-135- 3313_3686_3728-32361—,00.html. 

The information provided includes constituent load estimates 

for total phosphorus, chloride, total suspended solids (TSS), 

mercury, chromium, copper, and lead for selected tributaries in 

the WCMP. 

In 2009, the USGS published water-quality trend results 

for the selected streams in the WCMP for data collected during 

1998–2005 (Hoard and others, 2009). The 2009 USGS report 

describes water-quality trends observed during the first 7 years 

of the WCMP. Results of the assessment of the first 7 years of 

data identified several constituents with values either decreasing or increasing during 1998–2005. Upward trends were 

identified at multiple rivers for chloride, nitrite, and copper 

concentrations. Downward trends for turbidity, ammonia, total 

phosphorus, total Kjeldahl nitrogen (TKN), chromium, and 

lead also were identified at multiple rivers.

In 2013, the MDEQ published a report (Michigan 

Department of Environmental Quality, 2013) that provided a 

summary of various aspects of the WCMP. Spatial variability 

of water-quality constituents was assessed for the State of 

Michigan using a probabilistic sampling approach. In addition, 

trends during 1998–2008 for select water-quality parameters 

were estimated for the same 31 stream stations analyzed in 

Hoard and others (2009) as well as for select Great Lakes 

connecting channels and large bays (Roush, 2013). With the 

addition of 3 years of data collection, trend estimates did differ 

between the two reports. For example, chloride was identified 

as having a statistically significant trend (p-value 0.05) for 

nine locations in Roush (2013) as opposed to three locations in 

Hoard and others (2009).

Purpose and Scope

The purpose of this report is to summarize the estimated 

trends and loads for select water-quality constituents collected 

as part of the MDEQ WCMP from 1998 to 2013. Trends in 

water-quality constituents were estimated for 32 stream stations in 27 watersheds throughout Michigan using either the 

Seasonal Kendall test or Tobit regression trend estimation 

methods. Trends were estimated for select physical characteristics of water, nutrients, trace metals, and chloride. Annual 

constituent loads were estimated for the stream stations 

sampled 12 times per year using the Beale ratio estimator 

approach. Constituent loads were estimated for chloride, TSS, 

total phosphorus, mercury, lead, copper, and chromium for 30 

stations from 27 watersheds using flow and concentration data 

collected from 2002 to 2013. All chemical and physical data, 

and sample-related metadata, at all stations presented in this 

report are available online in the USGS National Water Information System (NWIS) database. These data can be accessed 

using station information documented in this report at https://

nwis.waterdata.usgs.gov/mi/nwis/qwdata. Flow adjusted concentrations and annual constituent loads are reported in this 

document and are not stored in the NWIS database. 
4 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents

Table 1. Stations sampled as part of the Michigan Water Chemistry Monitoring Program.

[Bold text indicates intensively sampled site; USGS, U.S. Geological Survey; EPA, U.S. Environmental Protection Agency; STORET, Storage and Retrieval 

System (water-quality data, EPA); Mich., Michigan]

Watershed 

number Station name

USGS 

station 

number

EPA 

STORET 

number

Latitude Longitude

1 Ontonagon River at Ontonagon, Mich. 04040018 660038 46.8674 -89.3171

2 Menominee River at Menominee, Mich. 04067648 550038 45.1064 -87.6357

3 Escanaba River at Wells, Mich. 040590345 210102 45.7811 -87.0675

4 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 210032 45.8408 -86.6688

5 Manistique River Above Manistique, Mich. 04057004 770073 45.9716 -86.2432

6 Tahquamenon River at Emerson, Mich. 04045510 170141 46.5564 -85.0387

7 Pine River near Charles, Mich. 04127925 490006 46.0570 -84.6570

8 Cheboygan River at Cheboygan, Mich. 04132052 160073 45.6339 -84.4811

9 Boardman River near Traverse City, Mich. 04127200 280014 44.6753 -85.6309

10 Manistee River at Parkdale, Mich. 04126010 510088 44.2642 -86.2954

11 Pere Marquette River at Scottville, Mich. 04122500 530027 43.9450 -86.2787

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 610273 43.3181 -86.0364

13 Muskegon River near Hersey, Mich. (upper) 04121621 670008 43.8472 -85.4322

14 Grand River near Eastmanville, Mich. (lower) 04119400 700123 43.0242 -86.0264

15 Grand River at Ionia, Mich. (upper) 04116000 340025 42.9720 -85.0692

16 Kalamazoo River at New Richmond, Mich. (lower) 04108660 030077 42.6517 -86.1078

17 Kalamazoo River near Augusta, Mich. (upper) 04105707 390057 42.3256 -85.3589

18 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 110628 42.0892 -86.4747

19 St. Joseph River at Mottville, Mich. (upper) 04099000 750273 41.8009 -85.7561

20 River Raisin at Monroe, Mich. 04176540 580046 41.9134 -83.3847

21 Huron River at Rockwood, Mich. 04175120 580364 42.0642 -83.2539

22 River Rouge at River Rouge, Mich. 04168550 820070 42.2806 -83.1288

23 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 500233 42.5839 -82.8827

24 Black River at Port Huron, Mich. 04160075 740385 42.9944 -82.4450

25 Flint River near Fosters, Mich. 04149000 730285 43.3084 -83.9536

26 Cass River near Bridgeport, Mich. 04152002 730024 43.3650 -83.9550

27 Shiawassee River near Fergus, Mich. 04145000 730023 43.2547 -84.1055

28 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 730025 43.3936 -84.0150

29 Saginaw River at Weadock Road at Essexville, Mich. 04157065 090177 43.6281 -83.8366

30 Au Sable River near Au Sable, Mich. 04137500 350061 44.4364 -83.4339

31 Thunder Bay at Alpena, Mich. 04135020 040123 45.0708 -83.4378

32 Black River near Port Huron, Mich. 04160055 740267 43.0175 -82.4530
Approach 5

Approach

Monitoring Program Design

The sample design for the WCMP has been described 

in detail in previous reports (Roush, 2013; Hoard and others, 

2009). However, the monitoring program and water-quality 

sample design for the sampling stations and data used for this 

report are described in this section. Selected sampling stations were designated as either intensive or integrator stations 

(fig. 1). 

From 2001 to 2013, 6 intensive stations were sampled 

12 times annually. These samples were not collected at even 

intervals during the year, instead eight samples were collected targeting high-flow events. Samples also were collected 

between 1998 and 2000; however, samples were not collected 

continuously during that period. Samples were collected during the part of the year when rivers were free of ice, which in 

most cases was March through November. 

The other type of sampling station studied during this 

program was the integrator station (fig. 1). Integrator stations were sampled at varying frequency, but were typically sampled four times annually. During a typical year, an 

integrator station was sampled at approximately even intervals 

during the ice-free period of the year. Each integrator station 

also was sampled 12 times annually on a 5-year rotating basis. 

The WCMP distribution of samples by year for intensive and 

integrator stations in Michigan is listed in table 2. 

 During the study period, the determination was made 

that the original station for monitoring the Black River watershed (Black River at Port Huron, Michigan; USGS station 

04160075; watershed number 24) was likely representing 

a mix of Lake Huron and the Black River. This station was 

moved in 2006 to the Black River near Port Huron, Mich. 

(USGS station 04160055; watershed number 32), which is further upstream and is not affected by mixing from Lake Huron. 

Therefore, trends were estimated from 2000 to 2005 for the 

Black River at Port Huron, Mich. (USGS station 04160075) 

and from 2006 to 2013 for the Black River near Port Huron, 

Mich. (USGS station 04160055). Trend results for both stations are reported. 

Sample Collection

For wadeable streams, water samples for trace metals 

and total mercury were collected as a single grab sample in 

the center of flow about 2–3 feet below the water surface. If 

a wading sample was not possible, water samples for mercury and trace metals were collected using a peristaltic pump 

either from a bridge or a boat with C-Flex tubing connected to 

6–15 feet of Teflon tubing. The Teflon tubing was connected to 

a Teflon counter weight and dropped below the surface, about 

2–3 feet, in the center of the channel. Water samples for mercury analysis were collected in 500 milliliter Teflon bottles, 

and water samples for analysis of trace metals were collected 

in 250 milliliter Teflon bottles. Before sampling, the tubing 

was rinsed with sample water for 5 minutes. Sample bottles 

were sealed in plastic bags and placed on ice in a cooler until 

final processing and transportation. The Teflon and C-Flex 

tubing were rinsed with 2-percent nitric acid and then rinsed 

in deionized water. The Teflon line was stored until the next 

sampling, whereas the C-Flex tubing was sent back to the Wisconsin State Lab of Hygiene. Water samples for mercury and 

trace metals were shipped in a cooler with ice to the Wisconsin 

State Lab of Hygiene, Madison, Wisconsin, within 48 hours of 

sample collection.

For wadeable streams and for streams where a wading sample was not possible, water samples for nutrients, 

chloride, and TSS were collected as a single grab sample in 

the center of flow about 2–3 feet below the water surface in 

500 milliliter polypropylene bottles by using grab, peristaltic 

pump, sampling can, and Van Dorn samplers, as appropriate. 

Sample bottles were placed on ice in a cooler until final processing and transportation. The samples that were analyzed 

for total organic carbon, nitrate, nitrite, ammonia, TKN, and 

total phosphorus were amended with 10 drops of concentrated 

sulfuric acid in the field to preserve the samples. Peristaltic 

tubing used for sampling was then cleaned using phosphate 

free detergent, rinsed with deionized water, and then stored 

for the next sampling. Samples were placed in a cooler with 

ice and shipped or transported to the MDEQ Environmental 

Laboratory, Lansing, Mich., within 48 hours of sample collection. Results for all analyses are stored in the USGS NWIS 

database (https://waterdata.usgs.gov/nwis/nwis).

Quality Assurance Samples

As part of the WCMP, field blank and replicate samples 

were collected for the purpose of quality assurance. Field 

blank samples were used to assess whether or not the sampling 

equipment or methods were introducing contamination to the 

samples collected. Field blank samples were collected using 

blank water of known chemical quality during sample processing and submitting that sample for analysis. Between 6 and 

15 blank samples were collected and analyzed annually for all 

the constituents. To put the blank sample analysis into context, 

knowledge of how to report lab results is required. For the 

nonmetal constituents, a minimum reporting level is the level 

at which a concentration can be quantified, so that above 

that level a value is reported and below that level the value 

is censored. For the trace metal constituents, two levels are 

used; a quantification level and a method detection level. The 

quantification level is the concentration at which a constituent 

can be quantified with certainty. The method detection level 

is defined as the smallest concentration that can be measured 

and reported with 99 percent confidence that the analyte concentration is greater than zero (Bonn, 2008). Any trace metal 

constituent with a result below the method detection level was 

reported as a censored value.
6 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Table 2. Michigan Water Chemistry Monitoring Program distribution of samples over time by station, 1998–2013. [Year indicates calendar year; plain text indicates integrator site, italicized text indicates samples included in trend analysis; bold text indicates intensive site; Mich., Michigan] Watershed number Station name Samples by year 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

1 Ontonagon River at Ontonagon, Mich. 0 0 3 4 4 4 4 4 4 4 12 4 4 4 4 122 Menominee River at Menominee, Mich. 0 0 3 4 12 4 4 4 4 12 4 4 4 12 12 43 Escanaba River at Wells, Mich. 0 13 6 4 4 4 4 12 4 4 4 4 12 8 4 44 Sturgeon River at County Road 499 at Nahma, Mich. 0 0 3 12 4 4 4 4 12 4 4 4 4 12 4 45 Manistique River Above Manistique, Mich. 0 13 3 4 4 4 12 4 4 4 4 12 4 12 4 46 Tahquamenon River at Emerson, Mich. 0 13 3 4 4 4 12 4 4 4 4 12 4 4 4 47 Pine River near Charles, Mich. 0 0 3 4 4 4 12 4 4 4 4 12 4 4 4 48 Cheboygan River at Cheboygan, Mich. 0 0 6 4 4 4 4 12 4 4 4 4 12 4 4 49 Boardman River near Traverse City, Mich. 0 0 0 4 4 12 4 4 4 4 12 4 4 4 4 12

10 Manistee River at Parkdale, Mich. 0 0 3 4 4 4 12 4 4 4 4 12 4 4 4 4

11 Pere Marquette River at Scottville, Mich. 0 12 6 4 5 4 4 12 4 4 4 4 12 8 4 4

12 Muskegon River near Bridgeton, Mich. (lower) 0 12 6 12 12 12 12 12 12 12 12 12 12 12 12 1213 Muskegon River near Hersey, Mich. (upper) 0 0 3 12 5 4 4 4 12 4 4 4 4 12 4 414 Grand River near Eastmanville, Mich. (lower) 0 13 6 12 12 12 12 12 12 12 12 12 12 12 12 1215 Grand River at Ionia, Mich. (upper) 0 0 3 12 4 4 4 5 12 4 4 4 4 12 4 416 Kalamazoo River at New Richmond, Mich. (lower) 0 13 6 12 12 12 12 12 12 12 12 12 12 12 12 1217 Kalamazoo River near Augusta, Mich. (upper) 0 0 3 4 4 4 12 4 4 4 4 12 4 12 4 418 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 0 12 3 12 4 4 4 12 4 4 4 4 4 12 4 419 St. Joseph River at Mottville, Mich. (upper) 0 0 6 4 4 4 4 4 12 4 4 4 12 4 4 420 River Raisin at Monroe, Mich. 12 0 3 4 4 12 4 4 4 4 12 4 4 4 4 1221 Huron River at Rockwood, Mich. 12 0 3 4 12 4 4 4 4 12 4 4 4 4 12 422 River Rouge at River Rouge, Mich. 13 0 6 4 4 4 4 12 4 4 4 4 12 4 4 423 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 13 0 6 12 12 12 12 12 12 12 12 12 12 12 12 1224 Black River at Port Huron, Mich. 0 0 3 4 4 4 4 4 0 0 0 0 0 0 0 025 Flint River near Fosters, Mich. 0 0 3 4 4 12 4 4 4 4 12 4 4 4 4 1226 Cass River near Bridgeport, Mich. 0 0 3 12 4 4 4 4 12 4 4 4 4 12 4 427 Shiawassee River near Fergus, Mich. 13 0 6 4 4 4 4 13 4 4 4 4 12 4 4 428 Tittabawassee River at Center Road near Saginaw, Mich. 13 0 3 4 12 4 4 4 4 12 4 4 4 4 12 429 Saginaw River at Weadock Road at Essexville, Mich. 8 0 0 12 12 12 12 12 12 12 12 12 12 12 12 1230 Au Sable River near Au Sable, Mich. 11 0 6 12 12 12 12 12 12 12 12 12 12 12 12 1231 Thunder Bay at Alpena, Mich. 11 0 6 4 4 4 4 12 4 4 4 4 12 4 4 432 Black River near Port Huron, Mich. 0 0 0 0 0 0 0 0 4 12 4 4 4 4 12 4
Approach 7

Concentrations that are estimated are values that have 

less certainty associated with their reported quantity. In the 

nonmetal constituents, estimated values were reported in 

cases when the lab had to adjust a procedure that may increase 

uncertainty in a result. For example, dilution may be required 

to analyze a sample or matrix interference may affect the analysis of the sample. In addition to the previous examples, the 

concentration of a trace metal constituent also can be qualified 

as estimated when a concentration is reported that is above 

the detection level but below the quantification level. The 

concentration is qualified as estimated because the reported 

concentration is less certain than a concentration above the 

quantification level. 

 In general, the blank sample results were below the 

minimum reporting level or quantification level for nonmetal and trace metal constituents, respectively. Constituents 

were only above the minimum reporting and quantification 

levels in about 4.5 percent of blank samples (table 3). Nutrient species were the most prevalent constituents with some 

quantifiable concentration in blank samples. Orthophosphate, 

nitrite, ammonia, and nitrate had estimated and detected levels 

in blanks at about 61, 48, 45, and 15 percent, respectively 

(table 3). These results indicate the possibility of some lowlevel contamination in the nutrient species collected during 

this study.

Sequential replicate samples were used to assist in determining the variability in constituent concentrations as a result 

of sample collection, processing, and natural variability in 

the stream. The number of replicate samples collected ranged 

from 243 to 263, dependent on the constituent (table 4). 

Comparison of the environmental samples to the replicate 

samples collected indicates that most constituents have a 

low relative percent difference in concentration between the 

original environmental sample and the replicate environmental 

sample (table 4). Median values of relative percent difference 

are low indicating good precision in analysis and generally 

low natural variability in the stream. However, although 

most constituents had low variability, the maximum relative 

percent difference could be high for certain constituents. The 

large value for maximum relative percent difference (table 4) 

indicates lower precision and higher environmental variability with the collection and analysis of mercury, copper, total 

phosphorus, and orthophosphate. For mercury, copper, total 

phosphorus, and orthophosphate the mean sample concentrations were generally near the minimum reporting level or 

quantification level. Consequently, small differences between 

the environmental and replicate samples can translate to a 

large percent difference among the sample results.

Water-Quality Trend Analysis

A trend is defined as a change in a single direction 

(upward/downward) in constituent concentrations expressed as 

percent change per year. The statistical methods for estimating 

trends in water quality were developed in ESTREND (Schertz 

and others, 1991) and converted to a library (S–ESTREND) 

for use in S–PLUS, a statistical software package. The library 

and documentation for S–PLUS can be obtained in Slack and 

others (2003). 

Table 3. Summary of quality control field blank samples collected for the Water Chemistry Monitoring Program.

[mg/L, milligrams per liter; N, Nitrogen; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus]

Constituent Number of 

censored results

Number of values 

below quantification 

but above the detection 

level

Number of samples 

above quantification 

level

Total samples

Ammonia (mg/L as N) 70 52 6 128

Chloride (mg/L) 117 6 5 128

Chromium (μg/L) 124 6 4 134

Copper (μg/L) 123 2 5 130

Lead (μg/L) 123 8 3 134

Mercury (ng/L) 128 4 3 135

Nitrate (mg/L as N) 100 14 3 117

Nitrite (mg/L as N) 67 43 18 128

Orthophosphate (mg/L as P) 50 70 8 128

Total phosphorus (mg/L as P) 114 11 3 128

Total Kjehldahl nitrogen (mg/L as N) 116 8 4 128

Total suspended solids (mg/L) 116 4 7 127
8 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Table 4. Summary of quality control replicate samples for the Water Chemistry Monitoring Program. [mg/L, milligrams per liter; N, Nitrogen; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus] Constituent Number of replicate samples Mean environmental sample concentration Mean replicate sample concentration Mean of the environmental/ replicate pair concentration Mean standard deviation Minimum relative percent difference1 Median relative percent difference1 Maximum relative percent difference1 Ammonia (mg/L as N) 245 0.047 0.047 0.047 0.001 0.00 2.020 85.7 Chloride (mg/L) 245 44.542 44.429 44.486 0.356 0.00 0.000 40.0 Chromium (μg/L) 259 1.088 1.078 1.083 0.067 0.00 6.259 84.3 Copper (μg/L) 258 1.807 1.843 1.825 0.069 0.00 1.771 167.0 Lead (μg/L) 263 0.829 0.839 0.834 0.034 0.00 3.306 112.6 Mercury (ng/L) 259 4.211 3.002 3.606 1.066 0.00 7.407 187.7 Nitrate (mg/L as N) 243 0.798 0.794 0.796 0.009 0.00 0.567 100.0 Nitrite (mg/L as N) 244 0.016 0.016 0.016 0.0003 0.00 0.000 100.0 Orthophosphate (mg/L as P) 244 0.018 0.018 0.018 0.001 0.00 0.000 136.8 Total phosphorus (mg/L as P) 247 0.061 0.061 0.061 0.002 0.00 2.985 143.3 Total Kjehldahl nitrogen (mg/L as N) 245 0.629 0.629 0.629 0.015 0.00 2.532 43.5 Total suspended solids (mg/L) 244 16.463 16.213 16.338 1.127 0.00 7.407 100.0

1Relative percent difference is defined as RPD Val Val Val Val = −

+ × ( ) (( ) / ) . | | 1 2 1 2 2 100
Approach 9

The nonparametric approach of the uncensored Seasonal 

Kendall test was chosen as the primary test for this study 

because of the characteristics of the water-quality data collected in the WCMP. The water-quality data collected as part 

of this program generally (1) were not normally distributed, 

(2) have seasonal variability in concentrations, (3) have variability in concentrations related to streamflow, (4) have some 

outlier concentration values, (5) have some censored concentration values, and (6) have some missing concentration values. 

The uncensored Seasonal Kendall test provides a means for 

analyzing data with those characteristics, whereas standard 

parametric procedures have difficulty evaluating this dataset 

(Hirsch and others, 1982; Hirsch and others, 1991).

The uncensored Seasonal Kendall test for trend detection 

has four principal data requirements. The period of record for 

a water-quality station must be at least 5 years (Schertz and 

others, 1991). The minimum number of samples that can be 

tested for a particular sampling station is at least 3 times the 

number of designated annual seasons, or at least a minimum of 

10 samples (Schertz and others, 1991). Additionally, a minimum percentage, in this case 30 percent, of the total possible 

number of seasonal water-quality values in the beginning and 

ending fifths of the record must be present (Schertz and others, 

1991). Finally, no more than 5 percent of the observed values 

can be censored (Schertz and others, 1991). Censored values 

are results for concentrations of constituents that are less than 

the laboratory method reporting level. These values are not 

quantified but are given a value of less than some reporting 

level.

Seasonal differences in concentrations of water-quality 

constituents can complicate the detection of trends. To detect 

a trend, the effect of seasonal differences on a constituent 

concentration needs to be removed. The ESTREND program 

removes the effect by dividing a year into seasons and only 

comparing sample data collected from similar seasons to estimate a trend (Schertz and others, 1991).

Seasons, for the different stations and constituents analyzed for trends, were defined on the basis of the sampling 

frequency at a station and the distribution of concentration data 

with time. The number of seasons per year used for this study 

was either 12, 6, 4, 3, or 2. The ESTREND program has an 

automated procedure for selecting the most appropriate number 

of seasons to use in the uncensored Seasonal Kendall test 

(Schertz and others, 1991). The program combines the beginning and ending fifths of the water-quality data for a constituent 

and compares that total to the middle three-fifths of the record. 

This procedure then calculates the total possible number of seasonal comparisons that could be made given a certain period of 

record and compares that total to the actual number of seasonal 

comparisons that can be made on the basis of the data available 

for a certain constituent at a station. The seasonal definition 

that had the largest number of seasons and that had 50 percent 

or more of the total possible seasonal matches was selected. 

Emphasis was placed on the beginning and ending fifths of the 

record, so the seasonal definition procedure weighted those 

portions of the record higher than the middle three-fifths of 

the record. When a season for a particular year had multiple 

samples, the most central value, with respect to time, that also 

was paired with a flow estimate was selected to represent the 

season (Schertz and others, 1991).

The concentrations of various water-quality constituents 

commonly are related to streamflow. As a result, the variance 

in the flow of a stream may be one of the major influences on 

a constituent concentration with time. In many cases, the influence of streamflow may be greater than the influence of other 

anthropogenic factors on constituent concentrations. In this 

case, any trend analysis test used essentially would be examining trends in streamflow as opposed to trends in constituent 

concentrations. To better understand the anthropogenic effect 

on the concentrations of water-quality constituents in streams, 

the effect that variation in streamflow has on constituent concentrations needs to be removed.

The ESTREND program provides a utility to remove the 

variability in constituent concentrations as a result of streamflow variability. This utility requires a streamflow estimate for 

each constituent concentration at each station being tested. 

The ESTREND program then computes a relation between the 

constituent concentration and the streamflow estimate, effectively creating a flow-adjusted concentration value (Schertz 

and others, 1991). For this study, a locally weighted scatter plot 

smoothing technique (Helsel and Hirsch, 2002) was used to 

develop the flow-adjusted concentration values. These flowadjusted concentration values were then tested for possible 

trends using the uncensored Seasonal Kendall test.

The parametric Tobit regression (Cohn, 1988; Schertz and 

others, 1991) also was used but only in cases where the data 

characteristics did not support using the uncensored Seasonal 

Kendall test. This trend estimation method was used for stations 

with constituents that had more than 5 percent but less than 

50 percent censored values. When 50 percent or more values for 

a constituent at a station were censored, then no trend tests were 

attempted. Only seven constituents analyzed for trends were in 

that category—ammonia, chromium, nitrate, nitrite, orthophosphate, total phosphorus, and TSS. A description of the Tobit 

regression equation, data requirements, and how the equation 

accounts for variability in constituent concentration as a result 

of flow and season, are in Cohn (1988), Schertz and others 

(1991), and Slack and others (2003). When the Tobit regression 

method was used for trend estimation, a log transformation of 

the flow and constituent concentrations was implemented and 

seasonal terms were included to account for variability in constituent concentrations related to flow and seasonality. 

A trend is considered to be statistically significant if the 

p-value of the trend test for a constituent is below a certain 

threshold. For this study, any trend with a p-value below 0.05 

was considered statistically significant. The p-value is the probability that a detected trend resulted from a chance arrangement 

of the data, rather than from an actual change in constituent 

concentration. To illustrate, for a p-value of 0.05 a 5-percent 

chance exists that a detected trend is an artifact of a chance 

arrangement of data as opposed to an actual trend in constituent concentrations. 
10 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents

Estimating Constituent Loads

Water-quality data from the WCMP were used in conjunction with streamflow data to compute loads at select stations. Loads were computed using the Autobeale load computation program (Richards and others, 1996) in stratified mode 

so that loads computed from the WCMP data can be compared 

to loads computed the same way by the U.S. Environmental 

Protection Agency (Dolan and Chapra, 2012). Annual constituent loads were computed for chloride, TSS, total phosphorus, chromium, copper, lead, and mercury. Because of 

the rotational basis of sampling, loads were computed at the 

integrator stations on a rotational basis following the 5-year 

rotation of intensive sampling based on the MDEQ watershedmanagement unit rotation (fig. 1, table 5). Annual loads also 

were computed at the six intensive stations for every year that 

the WCMP trend program was active (fig. 1). 

At the beginning of the WCMP, only 9 of 32 sampling 

locations selected for water-quality monitoring were either 

colocated or close enough to be considered flow equivalent 

with a USGS streamflow-gaging station. When a streamflowgaging station was not at the sampling station, a drainage-area 

multiplier (Archfield and Vogel, 2010) was determined for the 

area that contributed flow to that sample station. This multiplier was used in conjunction with the flow from a nearby 

streamflow-gaging station, usually upstream, to estimate the 

daily mean streamflow at the sample location. The Kalamazoo 

River near Augusta, Mich. (upper) (USGS station 04105707), 

Black River near Port Huron, Mich. (USGS station 04160055), 

and River Rouge (USGS station 04176540) were either the 

sum of multiple upstream gages or a combination of the sum 

of upstream gages and the use of a drainage area multiplier. 

Daily flows were provided by the dam operator for the Thunder Bay River at Alpena, Mich. (USGS station 04135020). 

Lastly, the Cheboygan River at Cheboygan, Mich. (USGS station 04132052) flow was estimated using a regression of flows 

from nearby gages. A compilation of the streamgages used to 

derive daily flow for each station that loads were estimated is 

listed in table 6.

Water-Quality Trend Results

Water-quality constituent results collected for the study 

are summarized in table 7. The table provides a comparison of 

the range of values seen statewide and for the rivers sampled 

as part of the State of Michigan WCMP. Results of individual 

rivers sampled are available in appendixes 1 and 2 and can be 

used to identify how a specific river compares to the composite distribution of all water-quality results from the WCMP. 

 Water-quality data from 32 rivers sampled as part of the 

WCMP were analyzed for trends in ammonia, chloride, chromium, copper, lead, mercury, nitrate, nitrite, orthophosphate, 

total phosphorus, TKN, and TSS. Water-quality data were 

collected between 1998 and 2013; however, water-quality 

data were not collected continuously during that period. For 

instance, the Saginaw River at Essexville was sampled in 1998 

and then not sampled again until 2001. The gap in that record 

caused problems with the trend estimation techniques used 

because too few records were at the beginning of the dataset. 

Therefore, only the periods with continuous data collection 

were used when estimating trends. For the Saginaw River, 

therefore, the trend estimate was for the period from 2001 to 

2013. Similarly, trends in constituent concentrations were only 

estimated from 2000 onward for the Clinton, Au Sable, Raisin, 

Huron, Rouge, Shiawassee, Tittabawassee, and Thunder Bay 

Rivers and do not include data from the sampling seasons during 1998–99. The number of samples by year for each station 

and the period during which trends were estimated are listed 

in table 2. To provide a cross-reference with figures and tables, 

the watershed number for each river described in the results is 

included in parentheses following the river name.

Trends in Chloride and Total Suspended Solids

Trends in chloride flow-adjusted concentrations may be 

the result of natural or anthropogenic sources to the environment. Some examples of natural sources are saline groundwater or dissolution of evaporite deposits in the Michigan 

Basin (Westjohn and Weaver, 1998). Anthropogenic sources 

of chloride include road-deicing compounds, plant fertilizer, 

and wastewater effluent (Hem, 1985). An increase in chloride 

is generally considered a decrease in water quality. Few values 

were censored so the uncensored Seasonal Kendall trend test 

was used for all stations.

Of the 32 rivers analyzed for trends in chloride, five 

had statistically significant trends (table 8). One river had an 

estimated downward trend, whereas four rivers had estimated 

upward trends. The downward trend was in the Cass River 

(26). The decrease in chloride for that river was 1.07 percent 

per year. The four upward trends were in the Menominee (2), 

Manistique (5), lower St. Joseph (18), and Black Rivers (24). 

The increase in chloride for these rivers was 2.80, 1.40, 0.90, 

and 5.43 percent per year, respectively. The spatial distribution 

of chloride trends in Michigan is shown in figure 2. A pattern 

is not obvious in the spatial distribution of chloride trends 

throughout the State. 

The concentration of the suspended material in a water 

sample are TSS. The TSS concentration is determined by 

filtering a water sample through a preweighed filter, then 

drying and weighing the filter to get the mass of material that 

was filtered. Large amounts of TSS in a water body can lead 

to increased water temperature, reduction of photosynthetic 

activity, and reduction in dissolved oxygen and, thus, degrading the water quality of the water body (Michigan Department 

of Environmental Quality, 2017). The TSS concentrations usually are correlated with streamflow, because high-flow events 

typically carry more suspended material than during low-flow 

events. Hence, flow-adjusted concentrations were used in 

the analyses. For TSS, two trend tests were used because of 
Water-Quality Trend Results 11

Table 5. U.S. Geological Survey station information and years for which annual loads were produced.[USGS, U.S. Geological Survey; STORET, Storage and Retrieval System (water-quality data, U.S. Environmental Protection Agency); Mich., Michigan; N, annual loads were not calculated; Y, annual loads were calculated; year indicates calendar year]

Watershed 

number Station name

USGS 

station 

number

STORET 

number 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

1 Ontonagon River at Ontonagon, Mich. 04040018 660038 N N N N Y N Y N N Y N Y2 Menominee River at Menominee, Mich. 04067648 550038 Y N N N N Y N N N Y Y N3 Escanaba River at Wells, Mich. 040590345 210102 N N N Y N N N N Y N N N4 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 210032 N N N N Y N N N N Y N N5 Manistique River Above Manistique, Mich. 04057004 770073 N N Y N N N N Y N Y N N6 Tahquamenon River at Emerson, Mich. 04045510 170141 N N Y N N N N Y N N N N7 Pine River near Charles, Mich. 04127925 490006 N N Y N N N N Y N N N N8 Cheboygan River at Cheboygan, Mich. 04132052 160073 N N N Y N N N N Y N N N9 Boardman River near Traverse City, Mich. 04127200 280014 N Y N N N N Y N N N N Y

10 Manistee River at Parkdale, Mich. 04126010 770073 N N Y N N N N Y N N N N

11 Pere Marquette River at Scottville, Mich. 04122500 530027 N N N Y N N N N Y N N N

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 610273 Y Y Y Y Y Y Y Y Y Y Y Y13 Muskegon River near Hersey, Mich. (upper) 04121621 670008 N N N N Y N N N N Y N N14 Grand River near Eastmanville, Mich. (lower) 04119400 700123 Y Y Y Y Y Y Y Y Y Y Y Y15 Grand River at Ionia, Mich. (upper) 04116000 340025 N N N N Y N N N N Y N N16 Kalamazoo River at New Richmond, Mich. (lower) 04108660 030077 Y Y Y Y Y Y Y Y Y Y Y Y17 Kalamazoo River near Augusta, Mich. (upper) 04105707 390057 N N Y N N N N Y N Y N N18 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 110628 N N N Y N N N N N Y N N19 St. Joseph River at Mottville, Mich. (upper) 04099000 750273 N N N N Y N N N Y N N N20 River Raisin at Monroe, Mich. 04176540 580046 N Y N N N N Y N N N N Y21 Huron River at Rockwood, Mich. 04175120 580364 Y N N N N Y N N N N Y N22 River Rouge at River Rouge, Mich. 04168550 820070 N N N Y N N N N Y N N N23 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 500233 Y Y Y Y Y Y Y Y Y Y Y Y25 Flint River near Fosters, Mich. 04149000 730285 N Y N N N N Y N N N N Y26 Cass River near Bridgeport, Mich. 04152002 730024 N N N N Y N N N N Y N N27 Shiawassee River near Fergus, Mich. 04145000 730023 N N N Y N N N N Y N N N28 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 730025 Y N N N N Y N N N N Y N29 Saginaw River at Weadock Road at Essexville, Mich. 04157065 090177 Y Y Y Y Y Y Y Y Y Y Y Y30 Au Sable River near Au Sable, Mich. 04137500 350061 Y Y Y Y Y Y Y Y Y Y Y Y31 Thunder Bay at Alpena, Mich. 04135020 040123 N N N Y N N N N Y N N N32 Black River near Port Huron, Mich. 04160055 740385 N N N N N Y N N N N Y N
12 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents

Table 6. U.S. Geological Survey stations used in the Water Chemistry Monitoring Program load computation.

[USGS, U.S. Geological Survey; Mich., Michigan]

Watershed 

number Station name

USGS station 

number

(sample 

collection)

USGS station number

(daily mean flow determination)

Drainage 

area

multiplier

1 Ontonagon River at Ontonagon, Mich. 04040018 04040000 1.03

2 Menominee River at Menominee, Mich. 04067648 04067500 1.03

3 Escanaba River at Wells, Mich. 040590345 04059000 1.00

4 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 04057510 1.20

5 Manistique River Above Manistique, Mich. 04057004 04056500 1.34

6 Tahquamenon River at Emerson, Mich. 04045510 04045500 1.07

7 Pine River near Charles, Mich. 04127925 04127918 1.41

8 Cheboygan River at Cheboygan, Mich. 04132052 Special1 1.00

9 Boardman River near Traverse City, Mich. 04127200 04126970 1.91

10 Manistee River at Parkdale, Mich. 04126010 04125550 1.25

11 Pere Marquette River at Scottville, Mich. 04122500 04122500 1.00

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 04121970 1.07

13 Muskegon River near Hersey, Mich. (upper) 04121621 04121500 1.15

14 Grand River near Eastmanville, Mich. (lower) 04119400 204119000 21.08

15 Grand River at Ionia, Mich. (upper) 04116000 04116000 1.00

16 Kalamazoo River at New Richmond, Mich. (lower) 04108660 04108660 1.00

17 Kalamazoo River near Augusta, Mich. (upper) 04105707 Sum of 04105500 and 04105700 1.00

18 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 04101500 1.15

19 St. Joseph River at Mottville, Mich. (upper) 04099000 04099000 1.00

20 River Raisin at Monroe, Mich. 04176540 04176500 1.02

21 Huron River at Rockwood, Mich. 04175120 04174500 1.17

22 River Rouge at River Rouge, Mich. 04168550 Sum of 04166500 and 04167000 

and 04168000

1.25

23 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 04165500 1.00

25 Flint River near Fosters, Mich. 04149000 04149000 1.00

26 Cass River near Bridgeport, Mich. 04152002 04151500 1.08

27 Shiawassee River near Fergus, Mich. 04145000 04145000 1.00

28 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 04156000 1.05

29 Saginaw River at Weadock Road at Essexville, Mich. 04157065 04157000 1.04

30 Au Sable River near Au Sable, Mich. 04137500 04137500 1.00

31 Thunder Bay at Alpena, Mich. 04135020 Dam3 1.00

32 Black River near Port Huron, Mich. 04160055 Sum of 04159492 and 04159900 1.08

1

Special, daily mean flow was computed via a weighted-linear regression analysis using the following formula (where the numbers represent the daily mean 

flow from the indicated USGS Station Numbers. Cheboygan daily mean flow (04132052)=(1522.7 × ln(04127997+04130500+0412890))−8072.3.

2

Drainage area multiplier used from water years 2002–09, in water year 2010 a USGS streamgage was installed at the same location as sample collection and 

was used for load computation from water year 2010–13.

3

Flow provided by dam operator.
Water-Quality Trend Results 13

Table 7. Composite summary of constituent concentration data collected for the Water Chemistry Monitoring Program 1998–2013.

[mg/L, milligrams per liter; N, Nitrogen; <, less than; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus]

Constituent Number of 

Samples Minimum 25 percent quantile Mean Median 75 percent quantile Maximum

Ammonia (mg/L as N) 3,085 <0.01 0.013 0.052 0.024 0.061 3.30

Chloride (mg/L) 3,086 <1 8.00 41.639 28.0 58.0 447

Chromium (μg/L) 3,011 <0.002 0.312 0.971 0.635 1.14 47.7

Copper (μg/L) 3,015 <0.001 0.536 1.789 1.34 2.21 393.000

Lead (μg/L) 3,069 0.013 0.146 0.889 0.441 1.07 50.8

Mercury (ng/L) 3,056 <0.01 1.14 3.323 2.09 4.04 304

Nitrate (mg/L as N) 3,048 0.002 0.084 0.886 0.440 1.32 10.9

Nitrite (mg/L as N) 3,083 <0.002 0.005 0.016 0.010 0.022 0.250

Orthophosphate (mg/L as P) 2,989 <0.003 0.005 0.022 0.010 0.026 4.00

Total Kjehldahl nitrogen (mg/L as N) 3,087 <0.1 0.400 0.665 0.630 0.880 4.70

Total phosphorus (mg/L as P) 3,087 <0.005 0.023 0.068 0.049 0.091 1.30

Total suspended solids (mg/L) 3,084 <4 4.00 18.737 11.0 21.0 1,700

the large number of censored values in the TSS dataset. The 

Seasonal Kendall trend test was used for the 14 rivers that had 

5 percent or fewer censored values. Tobit regression was used 

on 13 rivers with greater than 5 percent censored values. The 

remaining five rivers either had more than 50 percent censored 

values or had a censored data distribution that confounded the 

trend estimation; therefore, trends for TSS for those stations 

were not tested. Nine rivers that were tested for trends had 

statistically significant trends, all of which were downward 

(table 7, fig. 2). The lower Muskegon (12), upper Muskegon 

(13), lower Grand (14), upper Grand (15), lower St. Joseph 

(18), Clinton (23), Cass (26), Tittabawassee (28), and Saginaw 

(29) Rivers indicated downward trends for TSS. The percent 

decrease per year was 3.89, 4.08, 3.78, 6.72, 6.70, 5.69, 5.79, 

4.56, and 4.66, respectively (appendix 1). These results indicate a general improvement in water quality with respect to 

suspended solids in the State of Michigan. Detected trends in 

TSS were all in the Lower Peninsula (fig. 2), primarily within 

the central and southern portion of Michigan.

Trends in Nutrient Constituents

The nutrient constituents analyzed as part of this study 

were flow-adjusted concentrations of ammonia, nitrate, nitrite, 

orthophosphate, total phosphorus, and TKN. Sources of nutrient constituents include, but are not limited to, fertilizers, 

wastewater effluent, and by-products of combustion of fossil 

fuels. A direct relation exists between nutrient concentration 

and algal growth, which can lead to eutrophication of water 

bodies. In other words, as the concentration of nutrient species increase, algae growth is stimulated and eutrophication 

of a water body may result (U.S. Environmental Protection 

Agency, 2017).

Trends in orthophosphate were problematic to assess at 

many rivers because of the low concentrations detected in 

samples. Only 19 rivers could be tested because of limitations 

associated with the number of censored values and the distribution of the data with time. Fourteen of the rivers required 

the Tobit regression technique to detect a trend, whereas the 

remaining 5 rivers (table 9) were analyzed using the Seasonal Kendall trend test. Five rivers had estimated trends in 

orthophosphate concentrations, three were upward trends 

and two were downward trends. The three upward trends 

were estimated in the Ontonagon (1) and lower Grand (14) 

Rivers, as well as in the Black River (32) near Port Huron, 

at rates of 9.19, 3.15, and 21.10 percent per year, respectively (appendix 1). Downward trends were estimated in the 

Escanaba (3) and upper Kalamazoo (17) Rivers at rates of 

6.48 and 3.42 percent per year, respectively (appendix 1). The 

spatial distribution of orthophosphate trends in Michigan is 

shown in figure 2. Two trends are in the Upper Peninsula, and 

three trends are in the central and southern Lower Peninsula of 

the State. 

Trends in total phosphorus concentration were detected 

in 6 of the 32 rivers that were analyzed (table 9). All trends 

detected were downward, likely indicating improvement in 

water quality with respect to total phosphorus. Three rivers 

required the Tobit regression technique because more than 

5 percent of the concentrations were censored. The remaining 29 rivers were analyzed using the Seasonal Kendall trend 

test. Downward trends were estimated in the Pine (7), lower 

St. Joseph (18), Raisin (20), Clinton (23), Flint (25), and Cass 

(26) Rivers at percentages of 3.38, 4.24, 3.08, 3.37, 3.83, 

and 4.12, respectively (appendix 1). Spatially, the trends in 

total phosphorus are shown in figure 2. The trends are in the 

southern Lower Peninsula with the exception of the Pine (7) 

watersheds.
14 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents

Table 8. Trend results for chloride and total suspended solids at Michigan stream stations, 1999–2013.

[Mich., Michigan; -- ,no trend detected; U, upward trend with p-value less than or equal to 0.05; NA , trend not tested because of data 

limitationd; D, downward trend with p-value less than or equal to 0.05]

Watershed 

number Station name Chloride Total suspended solids

1 Ontonagon River at Ontonagon, Mich. -- --

2 Menominee River at Menominee, Mich. U NA

3 Escanaba River at Wells, Mich. -- --

4 Sturgeon River at County Road 499 at Nahma, Mich. -- --

5 Manistique River Above Manistique, Mich. U --

6 Tahquamenon River at Emerson, Mich. -- NA

7 Pine River near Charles, Mich. -- --

8 Cheboygan River at Cheboygan, Mich. -- NA

9 Boardman River near Traverse City, Mich. -- --

10 Manistee River at Parkdale, Mich. -- --

11 Pere Marquette River at Scottville, Mich. -- --

12 Muskegon River near Bridgeton, Mich. (lower) -- D

13 Muskegon River near Hersey, Mich. (upper) -- D

14 Grand River near Eastmanville, Mich. (lower) -- D

15 Grand River at Ionia, Mich. (upper) -- D

16 Kalamazoo River at New Richmond, Mich. (lower) -- --

17 Kalamazoo River near Augusta, Mich. (upper) -- --

18 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) U D

19 St. Joseph River at Mottville, Mich. (upper) -- --

20 River Raisin at Monroe, Mich. -- --

21 Huron River at Rockwood, Mich. -- --

22 River Rouge at River Rouge, Mich. -- --

23 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. -- D

24 Black River at Port Huron, Mich. U --

25 Flint River near Fosters, Mich. -- --

26 Cass River near Bridgeport, Mich. D D

27 Shiawassee River near Fergus, Mich. -- --

28 Tittabawassee River at Center Road near Saginaw, Mich. -- D

29 Saginaw River at Weadock Road at Essexville, Mich. -- D

30 Au Sable River near Au Sable, Mich. -- NA

31 Thunder Bay at Alpena, Mich. -- NA

32 Black River near Port Huron, Mich. -- --
Water-Quality Trend Results 15

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Total suspended solids

EXPLANATION

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Orthophosphate

Upward trend

Downward trend

Watershed boundary

and number

Base modified from the Michigan GIS open data portal, 2017 

and the Watershed Boundary Dataset, 2017, 1:8,433,662

World Geodetic System, 1984

N

Figure 2. Trend results for chloride, total suspended solids, total phosphorus, and orthophosphate by Michigan watershed.
16 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Table 9. Trend results for select nutrient constituents at Michigan stream stations, 1999–2013. [Mich., Michigan; -- , no trend detected; NA, trend not tested because of data limitations; U, upward trend with p-value less than or equal to 0.05; D, downward trend with p-value less than or equal to 0.05] Watershed number Station name Total Kjeldahl nitrogen Ammonia Nitrate Nitrite Orthophosphate Phosphorus

1 Ontonagon River at Ontonagon, Mich. -- -- -- NA

U --

2 Menominee River at Menominee, Mich. --

D -- NA NA --

3 Escanaba River at Wells, Mich.

U -- -- NA

D --

4 Sturgeon River at County Road 499 at Nahma, Mich. -- -- -- NA NA --5 Manistique River Above Manistique, Mich. -- -- -- NA NA --6 Tahquamenon River at Emerson, Mich. -- -- -- NA NA --7 Pine River near Charles, Mich. -- -- -- -- --

D

8 Cheboygan River at Cheboygan, Mich. -- -- -- NA NA --9 Boardman River near Traverse City, Mich. -- -- -- NA NA --

10 Manistee River at Parkdale, Mich. -- --

D NA NA --

11 Pere Marquette River at Scottville, Mich. -- -- -- NA -- --

12 Muskegon River near Bridgeton, Mich. (lower) -- -- -- NA NA --13 Muskegon River near Hersey, Mich. (upper) -- -- -- -- NA --14 Grand River near Eastmanville, Mich. (lower)

D

D --

D

U --

15 Grand River at Ionia, Mich. (upper)

D -- -- -- -- --

16 Kalamazoo River at New Richmond, Mich. (lower)

D

D -- -- -- --

17 Kalamazoo River near Augusta, Mich. (upper) --

D -- --

D --

18 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) -- -- -- -- --

D

19 St. Joseph River at Mottville, Mich. (upper) --

D

D -- NA --

20 River Raisin at Monroe, Mich. --

D --

D --

D

21 Huron River at Rockwood, Mich. -- --

D -- NA --

22 River Rouge at River Rouge, Mich. --

U

U

U -- --

23 Clinton River at Gratiot Avenue at Mt. Clemens, Mich.

D

D --

D --

D

24 Black River at Port Huron, Mich. -- -- -- -- -- --25 Flint River near Fosters, Mich. --

D -- -- --

D

26 Cass River near Bridgeport, Mich. --

D -- -- --

D

27 Shiawassee River near Fergus, Mich. -- -- -- -- -- --28 Tittabawassee River at Center Road near Saginaw, Mich. --

D -- -- -- --

29 Saginaw River at Weadock Road at Essexville, Mich. -- -- -- -- -- --30 Au Sable River near Au Sable, Mich. --

D

D NA NA --

31 Thunder Bay at Alpena, Mich. -- -- -- NA NA --32 Black River near Port Huron, Mich.

U -- -- --

U --
Water-Quality Trend Results 17

Trends in ammonia were detected more frequently than 

any other nutrient constituent. Trends were estimated at 12 of 

the 32 rivers analyzed. Two rivers had more than 5 percent of 

the ammonia results reported as censored values. Therefore, 

the Tobit regression technique was used for those two rivers, 

and the seasonal Kendall trend test was used for the remainder 

of the rivers (table 9). Of the 12 rivers with observed trends, 

11 of the trends were downward and 1 trend was upward. The 

spatial distribution of ammonia trends in Michigan is shown 

in figure 3. The large number of rivers with downward trends 

throughout the State indicates an overall improvement in 

water quality with respect to ammonia. Only one river that 

was monitored indicated upward trends in ammonia, the River 

Rouge (22), with trends increasing at 5.39 percent per year 

(appendix 1). 

Nitrate trends were detected in 5 of 32 rivers and all but 1 

of those trends was downward, much like the ammonia results 

(table 9). Seven rivers had more than 5 percent of the nitrate 

results reported as censored values. For those seven rivers, 

the Tobit regression technique was used to estimate trends, 

and the remaining rivers were analyzed using the Seasonal 

Kendall trend test. The spatial distribution of nitrate trends in 

Michigan is shown in figure 3. The distribution is similar to 

that of ammonia, but with fewer trends on the eastern one-half 

of the State. The Manistee (10), upper St. Joseph (19), Huron 

(21), and Au Sable (30) Rivers had significant downward 

trends at rates of 2.17, 1.53, 7.49, and 3.65 percent per year, 

respectively (appendix 1). The River Rouge (22) was the only 

station with an upward trend in nitrate at 3.83 percent per year 

(appendix 1). 

Trends in nitrite were problematic to assess mostly 

because concentrations were low and were censored more 

frequently than other constituents. Trends only could be 

analyzed for 19 of the 32 rivers because of limitations associated with the number of censored values and the distribution 

of the data with time. Of the 19 rivers that could be tested, 11 

rivers required Tobit regression because more than 5 percent 

of the constituent concentrations were below the censoring 

level. The remaining eight rivers were tested by using the 

Seasonal Kendall trend test. Downward trends were estimated 

in three rivers (table 9)—the lower Grand (14), Clinton (23), 

and Raisin (20) Rivers, which declined at 2.66, 4.83, and 

3.91 percent per year, respectively (appendix 1). An upward 

trend was estimated in the River Rouge (22), which increased 

at 5.97 percent per year (appendix 1). The spatial distribution 

of nitrite trends in Michigan is shown in figure 3.

The TKN is the concentration of the sum of organic 

nitrogen, ammonia, and the ammonium ion in solution. All 32 

rivers were analyzed using the Seasonal Kendall trend test. 

Downward trends were estimated in four rivers and upward 

trends were estimated in two rivers (table 9). The rivers with 

downward trends were the lower Grand (14), upper Grand 

(15), lower Kalamazoo (16), and Clinton (23) Rivers at rates 

of 2.46, 2.24, 1.6, and 1.57 percent per year, respectively 

(appendix 1). The two upward trends were detected in the 

Escanaba River (3) and the Black River (32) near Port Huron 

at rates of 2.66 and 5.30 percent per year, respectively (appendix 1). The spatial distribution of TKN trends in Michigan 

is shown in figure 3. Trends are primarily in the southern 

and central Lower Peninsula with one increasing trend in the 

Upper Peninsula of the State. 

Trends in Trace Metals Concentrations

The watersheds monitored as part of this study were 

analyzed to detect trends in trace metal flow-adjusted concentrations, including chromium, copper, lead, and mercury. Trace 

metals are released to the environment from natural sources 

as well as from anthropogenic processes. Some anthropogenic 

sources of trace metals include industrial processing, wastewater effluent, and atmospheric deposition of materials released 

into the atmosphere through industrial processes. In addition 

to various industrial uses of lead, from the 1920s through 

the 1980s tetraethyl lead was added to “leaded” gasoline to 

increase power output from gasoline engines; therefore, lead 

is broadly distributed in the environment. At certain levels, 

trace metal constituents are toxic to humans (U.S. Environmental Protection Agency, 2016) as well as to aquatic organisms (Michigan Department of Environmental Quality, 2006b, 

2016).

Trends in chromium were estimated in 9 of 32 rivers and 

all of the trends were upward (table 10). The Seasonal Kendall 

test was used for four of the rivers analyzed. The remaining 

six rivers required the Tobit regression technique because 

greater than 5 percent of the chromium values were censored (appendix 1). Those rivers that had significant upward 

trends were the Menominee (2), Sturgeon (4), Manistique (5), 

Cheboygan (8), Boardman (9), lower Muskegon (12), upper 

St. Joseph (19), Au Sable (30), and Thunder Bay (31) Rivers 

at rates of 4.65, 7.16, 4.18, 16.8, 23.2, 5.65, 12.7, 26.7, and 

18.8 percent per year, respectively (appendix 1). The spatial 

distribution of chromium trends in Michigan is shown in 

figure 4. The trends shown are primarily in the Upper Peninsula and northern Lower Peninsula of the State. The prevalent 

upward trend generally indicates a decline in water quality. 

However, although the prevalence of upward trends may be a 

concern, the maximum concentrations measured at these rivers 

are still low (1.09–7.14 micrograms per liter) (appendix 1). The 

Michigan Rule 57 water-quality criteria final chronic value for 

aquatic environments with respect to chromium is dependent 

on the hardness of the water for a particular sample (Michigan 

Department of Environmental Quality, 2006b, 2016). Therefore, a specific number cannot be defined, rather a number 

that changes as the waters hardness changes. The maximum 

concentrations of the rivers with upward trends are still below 

the final chronic value for chromium of 109 and 92 micrograms 

per liter, respectively (appendix 1).

Trends in copper were detected in 4 of 32 rivers analyzed 

(table 10). All rivers were analyzed using the Seasonal Kendall 

analysis and four downward trends were estimated. The four 

downward trends for copper were at the Escanaba (3), lower 
18 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents

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EXPLANATION

Insufficient data for 

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Integrator

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and number

Base modified from the Michigan GIS open data portal, 2017 

and the Watershed Boundary Dataset, 2017, 1:8,433,662

World Geodetic System, 1984

N

Figure 3. Trend results for ammonia, nitrate, nitrite, and total Kjeldahl nitrogen by Michigan watershed.
Water-Quality Trend Results 19

Table 10. Trend results for trace metal constituents at Michigan stream stations, 1999–2013.

[Mich.,Michigan; --, no trend detected; U, upward trend with p-value less than or equal to 0.05; D, downward trend with p-value less than or 

equal to 0.05]

Watershed 

number Station name Chromium Copper Lead Mercury

1 Ontonagon River at Ontonagon, Mich. -- -- U --

2 Menominee River at Menominee, Mich. U -- D --

3 Escanaba River at Wells, Mich. -- D -- --

4 Sturgeon River at County Road 499 at Nahma, Mich. U -- -- U

5 Manistique River Above Manistique, Mich. U -- -- --

6 Tahquamenon River at Emerson, Mich. -- -- -- --

7 Pine River near Charles, Mich. -- -- -- U

8 Cheboygan River at Cheboygan, Mich. U -- -- U

9 Boardman River near Traverse City, Mich. U -- -- --

10 Manistee River at Parkdale, Mich. -- -- -- --

11 Pere Marquette River at Scottville, Mich. -- -- -- --

12 Muskegon River near Bridgeton, Mich. (lower) U -- -- --

13 Muskegon River near Hersey, Mich. (upper) -- -- -- --

14 Grand River near Eastmanville, Mich. (lower) -- -- D --

15 Grand River at Ionia, Mich. (upper) -- -- -- --

16 Kalamazoo River at New Richmond, Mich. (lower) -- D D --

17 Kalamazoo River near Augusta, Mich. (upper) -- -- -- --

18 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) -- -- D --

19 St. Joseph River at Mottville, Mich. (upper) U -- -- --

20 River Raisin at Monroe, Mich. -- D -- --

21 Huron River at Rockwood, Mich. -- -- -- --

22 River Rouge at River Rouge, Mich. -- -- -- --

23 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. -- D D --

24 Black River at Port Huron, Mich. -- -- -- --

25 Flint River near Fosters, Mich. -- -- D --

26 Cass River near Bridgeport, Mich. -- -- D --

27 Shiawassee River near Fergus, Mich. -- -- -- --

28 Tittabawassee River at Center Road near Saginaw, Mich. -- -- D --

29 Saginaw River at Weadock Road at Essexville, Mich. -- -- D --

30 Au Sable River near Au Sable, Mich. U -- -- U

31 Thunder Bay at Alpena, Mich. U -- -- --

32 Black River near Port Huron, Mich. -- -- -- --
20 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents

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EXPLANATION

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World Geodetic System, 1984

N

Figure 4. Trend results for chromium, copper, lead, and mercury by Michigan watershed.
Constituent Load Results 21

Kalamazoo (16), Raisin (20), and Clinton (23) Rivers at a rate 

of 3.32, 1.37, 2.32, and 2.31 percent per year, respectively 

(appendix 1). The spatial distribution of copper trends in 

Michigan is shown in figure 4. The downward trends are in the 

southern Lower Peninsula, with the exception of the Escanaba 

River (3) in the Upper Peninsula of the State. Similar to chromium, the maximum concentrations for the rivers with upward 

trends are still low (0.67 and 1.57 micrograms per liter). 

Similar to chromium, the copper Michigan Rule 57 waterquality criteria final chronic value is based on a waters hardness (Michigan Department of Environmental Quality, 2006b, 

2016). For these streams with upward trends, the maximum 

concentrations were below the final chronic value for copper 

of 6.9 and 5.3 micrograms per liter, respectively.

Trends in lead were detected in 10 of 32 rivers analyzed (table 10). Again, the data distribution was such that 

the Seasonal Kendall test could be used for all analyses of 

trends. All but one of the trends were downward, indicating 

a general improvement in water quality with respect to lead. 

The one upward trend was for the Ontonagon River (1) at a 

rate of 3.83 percent per year. The nine downward trends were 

at the Menominee (2), lower Grand (14), lower Kalamazoo 

(16), lower St. Joseph (18), Clinton (23), Flint (25), Cass (26), 

Tittabawassee (28), and Saginaw (29) Rivers at rates of 1.80, 

4.97, 2.33, 6.26, 3.91, 5.38, 5.45, 5.48, and 5.27 percent per 

year, respectively (appendix 1). The spatial distribution of 

lead trends in Michigan is shown in figure 4. The only upward 

trend is in the northernmost sampled river in the Upper Peninsula. The downward trends are primarily in the Lower Peninsula, with the exception of the Menominee River (2). For lead, 

Michigan Rule 57 water-quality criteria final chronic value 

also is based on a waters hardness (Michigan Department of 

Environmental Quality, 2016). The maximum value (17 micrograms per liter) of the only upward trend for the Ontonagon 

River (1) did exceed the final chronic value of 15.6 micrograms per liter for that sample. However, the maximum value 

of lead for that sample (May 10, 2006) was related to a runoff 

event with high flow and elevated sediment and other metal 

constituents in the river. The lead concentrations for the Ontonagon River (1) did not exceed the Rule 57 final chronic value 

for lead in any other sample because the previously described 

conditions were not observed again.

Trends in mercury were estimated in 4 of the 32 rivers 

analyzed (table 10). The Seasonal Kendall test was used 

to analyze all rivers and four upward trends were detected. 

The upward trends were detected in the Sturgeon (4), 

Pine (7), Cheboygan (8), and Au Sable (30) Rivers at rates 

of 5.21, 2.99, 7.12, and 3.43 percent per year, respectively 

(appendix 1). The spatial distribution of mercury trends in 

Michigan is shown in figure 4. The upward trends are in the 

Upper Peninsula and northern Lower Peninsula of the State. 

Maximum concentrations at the stations with increasing trends 

are still low, ranging from 1.43 to 45.05 nanograms per liter 

(appendix 1). Those values are below the Michigan Rule 

57 water-quality criteria final chronic value for mercury of 

770 nanograms per liter.

Trend Summary

During this study, samples were collected at 32 river 

sites, and for the constituents that were analyzed, 79 trends 

were detected—53 downward trends and 26 upward trends. 

The trend directions should be used in context with the constituent in deciding whether the trend indicates an improvement 

or impairment of a river. Trend results indicate that more constituents are declining (downward trend) than are increasing 

(upward trend); however, trend results do not necessarily indicate that the water quality in the State is improving. Rather, an 

examination of each constituent is needed to decide whether 

water quality in a river may be improving or degrading. For 

example, a downward trend in nutrient species might indicate 

improvement in water quality, whereas a downward trend in 

dissolved oxygen might indicate a decline in water quality.

In general, trends in nutrient species were downward; 30 

of the 38 detected trends were downward. The most prevalent 

trend in nutrient species was for ammonia, with 11 downward 

trends and 1 upward trend. Trends in trace metals were not as 

uniform as the other constituents. Lead and copper trends were 

typically downward, whereas chromium and mercury trends 

were mainly upward.

Almost every river sampled had an estimated trend with 

the exception of the Tahquamenon River (6), which had no 

trends in any water-quality constituents. A summary of the 

number of trends and type of trend by watershed is shown in 

figure 5. Some particular rivers with trends indicating apparent improvement in water quality are the lower Grand (14), 

lower Kalamazoo (16), Raisin (20), and Clinton (23) Rivers. 

The lower Grand River (14) had estimated downward trends 

in TSS, ammonia, nitrite, TKN, and lead (tables 8–10). The 

lower Kalamazoo River (16) had downward trends in ammonia, TKN, copper, and lead (tables 9–10). The River Raisin 

(20) had downward trends in ammonia, nitrite, total phosphorus, and copper (tables 9–10). The Clinton River (23) had 

the most downward trends of any of the rivers studied with 

downward trends in TSS, ammonia, nitrite, total phosphorus, 

TKN, copper, and lead (tables 8–10). Trends common among 

these rivers were improvements in water quality resulting from 

decreases in nutrient and some trace metal concentrations during the study period.

In contrast, only one station had more than two upward 

trends, indicating an overall decline in water quality. The 

River Rouge (22) had upward trends in ammonia, nitrite, and 

nitrate. The declines in water quality for this river are associated with nutrient increases during the study period.

Constituent Load Results

Load estimates are a function of streamflow and constituent concentration in the stream. As such, the variability in 

streamflow is directly related to the variability in constituent 

load. Much of the variability seen in load estimates from year 
22 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Number of trends

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

Watershed number (table 1)

6

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Figure 5. Number of upward and downward trends at Michigan stream stations.

to year is mostly because of variability in stream discharge. 

In addition, although large streams may have small concentrations of constituents in their water, the load may be high 

because of the large magnitude of flow that is discharged by 

that stream. For example, the Saginaw River (29) consistently 

has the maximum loads for the various constituents analyzed 

because it is one of the largest streams we analyzed in terms of 

streamflow.

Annual constituent loads were computed for chloride, 

TSS, total phosphorus, chromium, copper, lead, and mercury 

by using concentrations that were not flow adjusted at 31 stations throughout the study period (appendix 2). Annual loads 

were computed every year from 2002 to 2013 for the lower 

Kalamazoo (16), lower Grand (14), lower Muskegon (12), Au 

Sable (30), Clinton (23), and Saginaw (29) Rivers (referred 

to as the intensive stations), whereas load calculations for the 

remaining 25 stations were more irregular (tables 5 and 6). 

The number of stations analyzed for loads (31 stations) is not 

in conflict with the number of stations analyzed for trends (32 

stations), as the Black River (32) only had loads estimated in 

2006 and 2012. Thus, loads were only estimated for USGS 

station number 04160055 and not for the older USGS station 

number 04160075. In the Kalamazoo, Grand, and Muskegon 

River watersheds, where upstream and downstream locations 

were sampled, the ratio of the load in the upstream subwatershed to the total load computed at the mouth of the stream 

lower watershed was determined. To account for difference in 

drainage areas, yields (loads/drainage area) also were determined where annual loads were calculated. 

Annual Loads and Yields for Chloride, Total 

Suspended Solids, and Total Phosphorus

Annual variability was observed most prominently at 

the stations with the highest loads (figs. 6–8). The annual 

loads are primarily driven by flow in each of these watersheds and wetter years where annual flows were higher 

(fig. 9); total phosphorus, TSS, and chloride also were higher. 

Summary statistics for annual loads at the six stations that 
Constituent Load Results 23

0

200,000

400,000

600,000

800,000

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Total phosphorus load, in kilograms per year

EXPLANATION

Au Sable River near Au Sable, Michigan (30)

Clinton River at Gratiot Avenue at Mt. Clemens, Michigan (23)

Grand River near Eastmanville, Michigan (lower) (14)

Kalamazoo River at New Richmond, Michigan (lower) (16)

Muskegon River near Bridgeton, Michigan (lower) (12)

Saginaw River at Weadock Road at Essexville, Michigan (29)

0

20

40

60

80

100

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Year

Total phosphorus yield,

in kilograms per year per square kilometer

Figure 6. Annual total phosphorus loads (top) and yields (bottom) for six intensively monitored rivers, 2002–13.
24 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents

0

100,000,000

200,000,000

300,000,000

400,000,000

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Total suspended solids load, in kilograms per year

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Year

Total suspended solids yield, 

in kilograms per year per square kilometer

EXPLANATION

Au Sable River near Au Sable, Michigan (30)

Clinton River at Gratiot Avenue at Mt. Clemens, Michigan (23)

Grand River near Eastmanville, Michigan (lower) (14)

Kalamazoo River at New Richmond, Michigan (lower) (16)

Muskegon River near Bridgeton, Michigan (lower) (12)

Saginaw River at Weadock Road at Essexville, Michigan (29)

Figure 7. Annual total suspended solids (top) and yields (bottom) for six intensively monitored rivers, 2002–13.
Constituent Load Results 25

0

50,000,000

100,000,000

150,000,000

200,000,000

250,000,000

300,000,000

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Chloride load, in kilograms per year

0

10,000

20,000

30,000

40,000

50,000

60,000

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Year

Chloride yield, in kilograms per year per square kilometer

EXPLANATION

Au Sable River near Au Sable, Michigan (30)

Clinton River at Gratiot Avenue at Mt. Clemens, Michigan (23)

Grand River near Eastmanville, Michigan (lower) (14)

Kalamazoo River at New Richmond, Michigan (lower) (16)

Muskegon River near Bridgeton, Michigan (lower) (12)

Saginaw River at Weadock Road at Essexville, Michigan (29)

Figure 8. Annual chloride loads (top) and yields (bottom) for six intensively monitored rivers, 2002–13.
26 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents

20

40

60

80

100

120

140

160

180

200

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Year

Average annual streamflow, in cubic meters per second

EXPLANATION

Au Sable River near Au Sable, Michigan (30)

Clinton River at Gratiot Avenue at Mt. Clemens, Michigan (23)

Grand River near Eastmanville, Michigan (lower) (14)

Kalamazoo River at New Richmond, Michigan (lower) (16)

Muskegon River near Bridgeton, Michigan (lower) (12)

Saginaw River at Weadock Road at Essexville, Michigan (29)

Figure 9. Annual average streamflow for six intensively monitored rivers, 2002–13.
Comparison of Upper and Lower Watershed Yields 27

had 12 years of annual data from 2002 to 2013—lower 

Muskegon (12), lower Grand (14), lower Kalamazoo (16), 

Clinton (23), Saginaw (29), and Au Sable (30) Rivers—are 

listed in table 11. Out of the six intensively monitored stations, the annual loads for chloride, TSS, and total phosphorus were largest for the Saginaw (29) and Grand (14) Rivers, 

which also represent the largest drainage areas (16,110 and 

13,701 square kilometers [km2], respectively). In 2006, the 

Saginaw River (29) had the largest annual load estimates for 

TSS (431 million kilograms per year [kg/yr]) and total phosphorus (922,000 kg/yr). The Saginaw River (29) also had the 

largest chloride loads, 216 million kg/yr in 2011. The Saginaw River (29) watershed is a large watershed dominated by 

agricultural land use (fig. 1) often a source for sediment and 

phosphorus. In contrast, the Au Sable (30) River (4,504 km2) 

and Muskegon River (12) (6,423 km2) typically had the 

lowest annual loads for all three constituents. Both of the 

watersheds are in the northern portion of the Lower Peninsula dominated by undeveloped land use (fig. 1). In 2002, the 

Au Sable River (30) had the lowest estimated load for TSS 

and total phosphorus (29,800 kg/yr and 8,070 kg/yr, respectively). In 2003, the Au Sable River (30) had the lowest 

chloride load (6,230,000 kg/yr). These results are consistent 

with other Great Lake studies that have determined land use 

and drainage area have a significant influence on sediment 

and phosphorus loads (Robertson and Saad, 2011; Hayhurst 

and others, 2016).

To account for the different drainage area, yields were 

determined by dividing the annual load (kilogram per year) 

by the drainage area (square kilometers). The results for all 

studies stations are listed in appendix 2. Summary statistics 

and results for the intensive stations are listed in table 11 and 

shown in figures 6–8. The Clinton River (23) had the highest yield for chloride (65,753 kilograms per year per square 

kilometer [kg/yr/km2]), total phosphorus (104.5 kg/yr/km2), 

and TSS (34,507 kg/yr/km2) all in 2011. However, out of the 

dataset the Ontonagon River (1) had the greatest TSS yields 

(appendix 2). The lowest yields for total phosphorus and 

TSS were at the Au Sable River (30) in 2002 (about 1.8 and 

7 kg/yr/km2, respectively). For chloride, several rivers had 

lower yields than the lowest intensive station; the Au Sable 

River (30) in 2003. The rivers include the Sturgeon (4), 

Ontonagon (1), Manistique (5), Tahquamenon (6), Thunder 

Bay (31), Pine (7), and Menominee (2) Rivers.

Although the Clinton River (23) had moderate loads 

compared to larger drainage areas of the Saginaw (29) and 

Grand (14) Rivers, the yield of chloride was considerably 

higher than all of the other intensively monitored stations 

(fig. 8). The Clinton River (23) average annual yield for 

chloride was 42,257 kg/yr/km2 compared to the next highest 

of 14,924 kg/yr/km2 at the Saginaw River (29) (table 11). 

The Clinton River (23) also had higher average total phosphorus and TSS yields compared to the other five intensively 

monitored stations. 

Annual Loads of Trace Metals

Annual loads for the trace metals (chromium, copper, 

lead, and mercury) follow similar patterns to TSS and total 

phosphorus at the intensive stations (table 12). The Saginaw 

(29) and lower Grand (14) Rivers had the largest annual loads 

for all four metals; again, these rivers also represent larger 

drainage areas. When considering drainage areas, results 

indicate the Clinton River (23) has the highest yields for each 

of the trace metals. 

From 2002 to 2013, the maximum chromium load 

observed during was 18,700 kg/yr in the Ontonagon River 

(1) in 2008 (appendix 2). The greatest observed loads were 

in the Ontonagon (1), Saginaw (29), and lower Grand (14) 

Rivers; the Saginaw River (29) had 6 of the 10 highest chromium loads within the dataset. The minimum chromium load 

observed in Michigan was 4.4 kg/yr in the Au Sable River (30) 

in 2003. The 10 lowest observed loads were in the Au Sable 

(30), Boardman (9), Cheboygan (8), Thunder Bay (31), Pere 

Marquette (11), Shiawassee (27), and Sturgeon (4) Rivers. 

During the study period, the maximum cooper load was 

19,400 kg/yr observed in the Saginaw River (29) in 2006 

(appendix 2). The greatest copper loads were observed in the 

Saginaw (29), Ontonagon (1), and lower Grand (14) Rivers. The minimum observed copper load was 51 kg/yr in the 

Boardman River (9) in 2003. The lowest observed loads of 

copper were observed in the Boardman (9), Sturgeon (4), Au 

Sable (30), and Thunder Bay (31) Rivers.

The maximum annual load of lead was 15,800 kg/yr in 

the Saginaw River (29) in 2006 (appendix 2). The greatest 

observed loads were in the Saginaw (29) and lower Grand 

(14) Rivers. The minimum annual load of lead observed was 

28 kg/yr in the Au Sable River (30) in 2010. The smallest 

observed loads of lead during the study period were in the Au 

Sable (30), Sturgeon (4), Boardman (9), Cheboygan (8), and 

Thunder Bay (31) Rivers.

The maximum load of mercury was 69.4 kg/yr in the 

Saginaw River (29) in 2006 (appendix 2). The greatest 

observed loads during the study were in the Saginaw (29), 

lower Grand (14), and Menominee (2) Rivers. The minimum 

load of mercury was 0.34 kg/yr, in the Au Sable River (30) in 

2010. Rivers with the smallest loads of mercury included the 

Au Sable (30), Boardman (9), Shiawassee (27), and Cheboygan (8) Rivers.

Comparison of Upper and Lower 

Watershed Yields

During the WCMP study, contributing subwatersheds 

were sampled in the same year for three of the major river 

basins; Kalamazoo, Grand, and Muskegon. Yields were compared at the upper watershed and lower watershed for chloride, 

TSS, and total phosphorus to determine if major load contributions differed in these large watersheds (fig. 10). 
28 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Table 11. Water Chemistry Monitoring Program load and yield summary statistics for chloride, total suspended solids, and total phosphorus at intensively monitored stations, 2002–13. [USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan] Watershed number Station name USGS station number Drainage area, km2 Summary statistic Annual mean discharge 

m3/s

Chloride Total suspended solids Total phosphorus 

Load, in

 kg/yr

Yield, in

 kg/yr/km2

Load, in 

kg/yr

Yield, in 

kg/yr/km2

Load, in 

kg/yr

Yield, in 

kg/yr/km2

12 Muskegon River near Bridgeton, 

Mich. (lower) 

04122030 6,420 Maximum 76.5 39,000,000 6,072 197,000,000 30,670 208,000 32.38 

Median 61.6 34,250,000 5,332 20,800,000 3,238 57,950 9.02 Minimum 44.8 28,200,000 4,390 6,820,000 1,062 35,600 5.54 Average 62.6 33,900,000 5,278 35,643,333 5,549 69,417 10.81 

14 Grand River near Eastmanville, 

Mich. (lower)

04119400 13,700 Maximum 186.2 225,000,000 16,422 236,000,000 17,225 746,000 54.45 

Median 129.3 188,000,000 13,722 118,000,000 8,612 539,500 39.38 Minimum 73.8 130,000,000 9,488 59,900,000 4,372 256,000 18.68 Average 132.1 184,583,333 13,472 119,208,333 8,701 512,583 37.41 

16 Kalamazoo River at New Richmond, Mich. (lower) 04108660 5,050 Maximum 88.7 93,600,000 18,533 80,900,000 16,018 241,000 47.72 Median 61.1 75,400,000 14,929 33,000,000 6,534 159,000 31.48 

Minimum 34.5 61,500,000 12,177 22,500,000 4,455 93,800 18.57 Average 62.2 75,191,667 14,888 36,716,667 7,270 174,233 34.50 

23 Clinton River at Gratiot Avenue at 

Mt. Clemens, Mich.

04165553 1,900 Maximum 31.6 125,000,000 65,753 65,600,000 34,507 198,000 104.15 

Median 17.9 76,700,000 40,346 24,500,000 12,888 88,750 46.68 Minimum 12.9 52,000,000 27,353 3,400,000 1,788 50,200 26.41 Average 19.4 80,333,333 42,257 29,491,667 15,513 103,917 54.66 

29 Saginaw River at Weadock Road at 

Essexville, Mich.

04157065 16,100 Maximum 192.2 297,000,000 18,436 431,000,000 26,754 922,000 57.23 

Median 135.9 242,500,000 15,053 182,500,000 11,329 546,500 33.92 Minimum 69.8 193,000,000 11,980 40,900,000 2,539 227,000 14.09 Average 139.4 240,416,667 14,924 182,608,333 11,335 550,167 34.15 

30 Au Sable River near Au Sable, 

Mich.

04137500 4,500 Maximum 42.4 10,500,000 2,331 5,280,000 1,172 13,700 3.04 

Median 36.9 7,455,000 1,655 2,260,000 502 12,150 2.70 Minimum 32.1 6,230,000 1,383 29,800 6.62 8,070 1.79 Average 37.3 7,620,000 1,692 2,407,817 535 11,428 2.54 
Comparison of Upper and Lower Watershed Yields 29

Table 12. Water Chemistry Monitoring Program load and yield summary statistics for cooper, chromium, lead, and mercury at intensively monitored stations, 2002–13.[USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan]

Watershed 

number Station name

USGS 

station 

number

Drainage 

area, 

in km2

Summary 

statistic

Annual 

mean 

discharge, 

in m3/s

Cooper Chromium Lead Mercury

Load, in 

kg/yr

Yield, in 

kg/yr/km2

Load, in 

kg/yr

Yield, in 

kg/yr/km2

Load, in 

kg/yr

Yield, in 

kg/yr/km2

Load, in 

kg/yr

Yield, in kg/

yr/km2

12 Muskegon River 

near Bridgeton, Mich. (lower) 

04122030 6,420 Maximum 76.5 4,480 0.697 3,920 0.610 4,190 0.652 14.1 0.00220

Median 61.6 1,480 0.230 797 0.124 398 0.062 2.57 0.00042Minimum 44.8 892 0.139 87.6 0.014 168 0.026 1.48 0.00023Average 62.6 1,699 0.265 999 0.155 717 0.112 3.75 0.00061

14 Grand River near 

Eastmanville, Mich. (lower)

04119400 13,700 Maximum 186.2 14,900 1.088 9,140 0.667 10,100 0.737 33.4 0.00244

Median 129.3 10,535 0.769 5,595 0.408 5,660 0.413 19.4 0.00155Minimum 73.8 6,230 0.455 1,280 0.093 2,660 0.194 8.02 0.00059Average 132.1 10,800 0.788 5,908 0.431 5,859 0.428 20.3 0.00153

16 Kalamazoo River at 

New Richmond, Mich. (lower)

04108660 5,050 Maximum 88.7 4,310 0.853 2,660 0.527 3,950 0.782 14.6 0.00289

Median 61.1 2,930 0.580 1,575 0.312 2,240 0.444 10.1 0.00204Minimum 34.5 1,850 0.366 380 0.075 1,610 0.319 6.21 0.00137Average 62.2 3,028 0.599 1,632 0.323 2,524 0.500 10.7 0.00220

23 Clinton River at 

Gratiot Avenue at Mt. Clemens, Mich.

04165553 1,900 Maximum 31.6 6,890 3.624 3,820 2.009 6,130 3.225 11.2 0.00589

Median 17.9 2,675 1.407 1,425 0.750 1,700 0.894 3.80 0.00223Minimum 12.9 1,380 0.726 691 0.363 772 0.406 1.91 0.00100Average 19.4 3,026 1.592 1,722 0.906 2,177 1.145 4.74 0.00256

29 Saginaw River at 

Weadock Road at Essexville, Mich.

04157065 16,100 Maximum 192.2 19,400 1.204 12,100 0.751 15,800 0.981 69.4 0.00431

Median 135.9 11,900 0.739 8,145 0.506 8,335 0.517 22.0 0.00155Minimum 69.8 5,030 0.312 1,560 0.097 2,530 0.157 7.00 0.00043Average 139.4 12,099 0.751 7,389 0.459 7,559 0.469 28.1 0.00180

30 Au Sable River 

near Au Sable, Mich.

04137500 4,500 Maximum 42.4 475 0.105 527 0.117 73.0 0.016 1.00 0.00022

Median 36.9 350 0.078 255 0.057 46.5 0.010 0.547 0.00012Minimum 32.1 219 0.049 4.4 0.001 28.0 0.006 0.340 0.00008Average 37.3 340 0.075 239 0.053 49.5 0.011 0.558 0.00013
30 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents

0

50

100

150

2011 Kalamazoo

Total phosphorus yield, 

in kilograms per day per square kilometer

EXPLANATION

Upper river station

Lower river station

2004 Kalamazoo

2009 Kalamazoo

2006 Grand

2011 Grand

2006 Muskegon

2011 Muskegon

0

25,000

50,000

75,000

Total suspended solids yield, 

in kilograms per day per square kilometer

0

10,000

20,000

30,000

40,000

50,000

Chloride yield, 

in kilograms per day per square kilometer

95 percent confidence 

interval of estimate

Figure 10. Comparison of chloride (top), total suspended solids (middle), and total phosphorus (bottom) yields for lower and upper 

watershed sampling locations.
References Cited 31

The TSS and total phosphorus yields were similar at the 

upper and lower watershed with a couple exceptions. Yields 

seemed to be higher in 2006 at the lower Muskegon River 

(12); however, the load estimation had a large uncertainty and, 

therefore, a true difference was difficult to determine. A single 

event on March 13, 2006, at the lower Muskegon River (12) 

(USGS station 04122030, Muskegon River near Bridgeton, 

Mich.) resulted in a sample being collected with higher flows 

and higher concentrations. This biased the annual load for 

this station, resulting in a large uncertainty value. In 2009, 

the TSS yield was slightly higher at the lower Kalamazoo 

River (16) compared to the upper station; otherwise yields 

were within error estimation. Similar results also were seen 

for total phosphorus where yields for most comparisons were 

similar. Exceptions were in 2011 in the Grand River where a 

higher yield was in the upper watershed (15) and in 2009 in 

the Kalamazoo River where a higher yield was in the lower 

watershed (16). Although loads may be greater downstream 

in the watershed (appendix 2), when drainage area is considered, yields are similar for these stations on the years where 

comparisons could be made. 

Chloride yields were greater at the lower watershed location for the Muskegon and Kalamazoo Rivers than the upper 

watershed location. These yield results were not similar for the 

Grand River watershed. The lower Kalamazoo River (16) had 

about 10,000 kilograms per day per square kilometer greater 

yield for chloride than the upper Kalamazoo River (17) for 

all three sampling dates during the study period. Similarly, 

the lower Muskegon River (12) had greater yields than the 

upper Muskegon River (13) for both sampling dates during 

the study period. The difference in chloride yields could be a 

result of several factors including land-use nonpoint source 

such as runoff from land surfaces or point sources such as 

wastewater effluent. Unlike suspended sediment and particulate phosphorus, chloride is often a dissolved constituent that 

is more conservative so removal from the system by physical 

or biological processes is less likely. Therefore, chloride could 

be accumulating in the river as it moves downstream. Further 

studies would be needed to determine the source or reasons for 

difference in the watershed.

Summary

In 1998, the Michigan Department of Environmental 

Quality and the U.S. Geological Survey began the Water 

Chemistry Monitoring Program for select streams in the State 

of Michigan. Objectives of this program were to provide assistance with (1) statewide water-quality assessments, (2) the 

National Pollutant Discharge Elimination System permitting 

process, and (3) water-resource management decisions. As 

part of this program, water-quality data collected from 1998 

to 2013 were analyzed to identify potential trends in waterquality constituents and estimate constituent loads from select 

streams in Michigan.

Water-quality data from 32 rivers sampled as part of 

the Water Chemistry Monitoring Program were analyzed for 

trends in ammonia, chloride, chromium, copper, lead, mercury, nitrate, nitrite, orthophosphate, total phosphorus, total 

Kjeldahl nitrogen, and total suspended solids. Trend analysis 

on the various water-quality data in the form of flow-adjusted 

concentrations was done using either the uncensored Seasonal Kendall test, or through Tobit regression. Trend analysis 

identified 79 trends in water-quality constituents among the 32 

river stations analyzed—53 downward trends and 26 upward 

trends were identified in the water-quality dataset. The most 

prevalent trend throughout Michigan streams was a downward trend for ammonia, primarily in the Lower Peninsula of 

Michigan. Several river stations analyzed for trends indicate 

an improvement in water quality during the study period 

and include the lower Grand, lower Kalamazoo, Raisin, and 

Clinton Rivers. However, trends in water-quality constituents 

indicate a decline in water quality at the Rouge River during 

the study period. 

In addition to trends, constituent loads were estimated for 

31 stations from 2002 to 2013 for stations that were sampled 

12 times per year. Loads were computed using the Autobeale 

load computation program, which used the Beale ratio estimator approach to estimate an annual load. Constituent loads 

were the largest in large watershed streams with the highest 

annual flows such as the Saginaw and Grand Rivers. Likewise, 

constituent loads were the smallest in smaller tributaries that 

were sampled as part of this program such as the Boardman 

and Thunder Bay Rivers. Rivers with paired upstream and 

downstream sampling locations were assessed to identify percent contribution of load on years when loads were estimated 

at both river stations.

Using the data from the Water Chemistry Monitoring 

Program, the trend and load analysis developed in this study 

can be used to identify areas that are improving and degrading 

with respect to water quality in the State of Michigan. Identification of watersheds will enable water-resource managers to 

further study these watersheds and determine factors that are 

contributing to the improvement or decline in water quality. 

In addition, the information can assist in developing strategies to meet Great Lakes goals in improving water-quality 

and mitigating issues in the Great Lakes basin such as harmful 

algal blooms and lake hypoxia. The continued monitoring and 

analysis of water quality of streams in Michigan will be helpful in assessing the effectiveness of any strategies employed to 

address water-quality issues.

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2008, at http://www.michigan.gov/documents/deq/wb-swas9805tribreport_222804_7.pdf.

Michigan Department of Environmental Quality, 2013, 

Michigan’s water chemistry monitoring program—A report 

of statewide spatial patterns 2005–2009 and fixed stations 

status and trends 1998–2008: MI/DEQ/WRD–13/005, 

accessed February 22, 2016, at http://www.michigan.gov/

documents/deq/wrd-swas-wcmp-0509report_431945_7.pdf.

Michigan Department of Environmental Quality, 2016, 

Rule 57 Water Quality Values: Michigan Department 

of Environmental Quality website, accessed January 4, 

2016, at http://www.michigan.gov/deq/0,4561,7-135-

3313_3681_3686_3728-11383—,00.html.
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Michigan Department of Environmental Quality, 2017, Water 

quality parameter information page: accessed May 20, 

2017, at http://www.michigan.gov/documents/deq/wrdnpdes-water-quality_570237_7.pdf.

Richards, R.P., Baker, D.B., Kramer, J.W., and Ewing, D.E., 

1996, Annual loads of herbicides in Lake Erie tributaries of 

Michigan and Ohio: Journal of Great Lakes Research, v. 22, 

no, 2, p. 414–428.

Robertson, D.M., and Saad, D.A., 2011, Nutrient inputs 

to the Laurentian Great Lakes by source and watershed 

estimated using SPARROW watershed models: Journal of 

the American Water Resources Association, v. 47, no. 5, 

p. 1011–1033, accessed October, 3, 2017, at https://doi.

org/10.1111/j.1752-1688.2011.00574.x.

Roush, Dawn, 2013, Michigan’s Water Chemistry Monitoring Program—A report of statewide spatial patterns 

2005–2009 and fixed station status and trends 1998–2008: 

Michigan Department of Environmental Quality Report 

MI/DEQ/WRD-13/005, 131 p. [Also available at http://

www.michigan.gov/documents/deq/wrd-swas-wcmp0509report_431945_7.pdf.]

Schertz, T.L., Alexander, R.B., and Ohe, D.J., 1991, The computer program Estimate TREND (ESTREND), a system for 

the detection of trends in water-quality data: U.S. Geological Survey Water-Resources Investigations Report 91–4040, 

68 p.

Slack, J.R., Lorenz, D.L., and others, 2003, USGS library 

for S–PLUS for Windows—Release 2.1: U.S. Geological 

Survey Open-File Report 2003–357, accessed October 23, 

2017, at https://pubs.er.usgs.gov/usgspubs/ofr/ofr03357.

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accessed October 29, 2017, at http://gis-michigan.opendata.

arcgis.com/.

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contaminants—Standards and regulations: U.S. Environmental Protection Agency website, accessed January 4, 

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epa.gov/nutrientpollution.

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April 15, 2017, at https://nrcs.app.box.com/v/huc.

Westjohn, D.B., and Weaver, T.L., 1998, Hydrogeologic 

framework of the Michigan Basin regional aquifer system: 

U.S. Geological Survey Professional Paper 1418, 47 p.

Appendixes 1–2
36 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013. [USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus] Watershed number Station name USGS station number Number of samples collected Number of censored results Minimum concentration Median concentration Maximum concentration Years of data used Seasons used Ammonia (mg/L as N)

1 Ontonagon River at Ontonagon, Mich. 04040018 70 2 0.002 0.008 0.25 14 22 Menominee River at Menominee, Mich. 04067648 87 6 0.003 0.011 0.047 14 NA3 Escanaba River at Wells, Mich. 040590345 91 0 0.015 0.056 0.194 15 34 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 79 0 0.002 0.017 0.062 14 65 Manistique River Above Manistique, Mich. 04057004 92 0 0.003 0.0165 0.053 15 36 Tahquamenon River at Emerson, Mich. 04045510 84 1 0.004 0.015 0.047 15 37 Pine River near Charles, Mich. 04127925 71 2 0.003 0.016 0.11 14 38 Cheboygan River at Cheboygan, Mich. 04132052 74 1 0.005 0.0155 0.035 14 39 Boardman River near Traverse City, Mich. 04127200 76 4 0.002 0.008 0.026 13 4

10 Manistee River at Parkdale, Mich. 04126010 71 1 0.002 0.018 0.047 14 3

11 Pere Marquette River at Scottville, Mich. 04122500 91 0 0.002 0.019 0.068 15 3

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 173 4 0.002 0.021 0.099 15 1213 Muskegon River near Hersey, Mich. (upper) 04121621 80 3 0.002 0.0135 0.089 14 414 Grand River near Eastmanville, Mich. (lower) 04119400 175 3 0.002 0.065 0.81 15 1215 Grand River at Ionia, Mich. (upper) 04116000 80 4 0.003 0.029 0.28 14 316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 175 6 0.004 0.035 0.3 15 1217 Kalamazoo River near Augusta, Mich. (upper) 04105707 79 2 0.004 0.038 0.15 14 418 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 91 5 0.002 0.015 0.31 15 319 St. Joseph River at Mottville, Mich. (upper) 04099000 74 1 0.004 0.0435 0.151 14 320 River Raisin at Monroe, Mich. 04176540 79 2 0.004 0.025 0.17 14 421 Huron River at Rockwood, Mich. 04175120 79 0 0.007 0.056 0.186 14 422 River Rouge at River Rouge, Mich. 04168550 74 1 0.01 0.151 3.3 14 323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 162 0 0.013 0.09 0.76 14 1224 Black River at Port Huron, Mich. 04160075 23 0 0.005 0.036 0.17 6 325 Flint River near Fosters, Mich. 04149000 79 1 0.005 0.04 0.93 14 326 Cass River near Bridgeport, Mich. 04152002 79 1 0.002 0.025 0.5 14 627 Shiawassee River near Fergus, Mich. 04145000 75 0 0.002 0.028 0.25 14 328 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 2 0.003 0.046 0.28 14 429 Saginaw River at Weadock Road at Essexville, Mich. 04157065 155 0 0.016 0.13 0.741 13 630 Au Sable River near Au Sable, Mich. 04137500 162 8 0.001 0.0145 0.047 14 631 Thunder Bay at Alpena, Mich. 04135020 74 1 0.002 0.018 0.054 14 332 Black River near Port Huron, Mich. 04160055 47 9 0.003 0.012 0.22 8 NA
Appendix 1 37

Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued[USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus]

Watershed 

number Station name

USGS 

station 

number

Number of 

samples 

collected

Number of 

censored 

results

Trend 

test 

used

Trend in 

constituent 

units per 

year

Trend as a 

percent per 

year

p-value of 

trend

Ammonia (mg/L as N)—Continued

1 Ontonagon River at Ontonagon, Mich. 04040018 70 2 SK <0.0001 0.042 1.0002 Menominee River at Menominee, Mich. 04067648 87 6 TR -0.0004 -2.681 0.0483 Escanaba River at Wells, Mich. 040590345 91 0 SK 0.0025 4.172 0.0954 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 79 0 SK -0.0004 -2.451 0.5665 Manistique River Above Manistique, Mich. 04057004 92 0 SK -0.0002 -1.294 0.2596 Tahquamenon River at Emerson, Mich. 04045510 84 1 SK -0.0005 -3.292 0.1667 Pine River near Charles, Mich. 04127925 71 2 SK -0.0003 -2.014 0.2688 Cheboygan River at Cheboygan, Mich. 04132052 74 1 SK -0.0005 -3.369 0.0969 Boardman River near Traverse City, Mich. 04127200 76 4 SK <0.0001 0.640 0.689

10 Manistee River at Parkdale, Mich. 04126010 71 1 SK -0.0006 -2.811 0.198

11 Pere Marquette River at Scottville, Mich. 04122500 91 0 SK -0.0008 -4.046 0.073

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 173 4 SK -0.0008 -3.573 0.06413 Muskegon River near Hersey, Mich. (upper) 04121621 80 3 SK -0.0006 -4.231 0.05214 Grand River near Eastmanville, Mich. (lower) 04119400 175 3 SK -0.0028 -5.515 0.00415 Grand River at Ionia, Mich. (upper) 04116000 80 4 SK 0.0005 1.723 0.83816 Kalamazoo River at New Richmond, Mich. (lower) 04108660 175 6 SK -0.0020 -5.793 0.01217 Kalamazoo River near Augusta, Mich. (upper) 04105707 79 2 SK -0.0040 -10.361 0.01318 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 91 5 SK -0.0005 -2.964 0.32619 St. Joseph River at Mottville, Mich. (upper) 04099000 74 1 SK -0.0035 -10.730 0.00120 River Raisin at Monroe, Mich. 04176540 79 2 SK -0.0017 -8.104 0.02521 Huron River at Rockwood, Mich. 04175120 79 0 SK -0.0013 -2.236 0.36922 River Rouge at River Rouge, Mich. 04168550 74 1 SK 0.0078 5.441 0.01623 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 162 0 SK -0.0072 -8.053 0.00224 Black River at Port Huron, Mich. 04160075 23 0 SK -0.0022 -5.431 0.19925 Flint River near Fosters, Mich. 04149000 79 1 SK -0.0023 -5.946 0.03326 Cass River near Bridgeport, Mich. 04152002 79 1 SK -0.0014 -5.699 0.03527 Shiawassee River near Fergus, Mich. 04145000 75 0 SK -0.0002 -0.782 0.92328 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 2 SK -0.0047 -12.235 0.00729 Saginaw River at Weadock Road at Essexville, Mich. 04157065 155 0 SK -0.0042 -3.014 0.23130 Au Sable River near Au Sable, Mich. 04137500 162 8 SK -0.0005 -3.749 0.00931 Thunder Bay at Alpena, Mich. 04135020 74 1 SK -0.0007 -3.909 0.10332 Black River near Port Huron, Mich. 04160055 47 9 TR -0.0004 -1.265 0.790 
38 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued [USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus] Watershed number Station name USGS station number Number of samples collected Number of censored results Minimum concentration Median concentration Maximum concentration Years of data used Seasons used Chloride (mg/L)

1 Ontonagon River at Ontonagon, Mich. 04040018 70 0 2 3 72 14 22 Menominee River at Menominee, Mich. 04067648 87 0 3 7.3 13 14 33 Escanaba River at Wells, Mich. 040590345 91 1 1 21 61 15 34 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 79 0 1.9 2 4 14 65 Manistique River Above Manistique, Mich. 04057004 92 0 1 2 3.7 15 36 Tahquamenon River at Emerson, Mich. 04045510 84 0 1.9 2 4 15 37 Pine River near Charles, Mich. 04127925 71 0 1 3 12 14 38 Cheboygan River at Cheboygan, Mich. 04132052 74 0 5.8 8 16 14 39 Boardman River near Traverse City, Mich. 04127200 76 0 7 8 34 13 4

10 Manistee River at Parkdale, Mich. 04126010 71 0 7.5 12 33 14 3

11 Pere Marquette River at Scottville, Mich. 04122500 91 0 5 13 51 15 3

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 173 0 11 19 26 15 1213 Muskegon River near Hersey, Mich. (upper) 04121621 80 0 2 16 72 14 414 Grand River near Eastmanville, Mich. (lower) 04119400 175 0 23 51 79 15 1215 Grand River at Ionia, Mich. (upper) 04116000 80 3 1 47.5 94 14 316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 175 0 21 42 62 15 1217 Kalamazoo River near Augusta, Mich. (upper) 04105707 79 0 13 39 59 14 418 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 91 0 18 31 45 15 319 St. Joseph River at Mottville, Mich. (upper) 04099000 74 0 15 23 34 14 320 River Raisin at Monroe, Mich. 04176540 79 0 21 45 64 14 421 Huron River at Rockwood, Mich. 04175120 79 0 68 97 174 14 422 River Rouge at River Rouge, Mich. 04168550 74 1 1 79.5 259 14 323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 162 0 38 151.5 447 14 1224 Black River at Port Huron, Mich. 04160075 23 0 12 28 70 6 325 Flint River near Fosters, Mich. 04149000 79 0 40 82 232 14 326 Cass River near Bridgeport, Mich. 04152002 79 0 15 40 88 14 627 Shiawassee River near Fergus, Mich. 04145000 75 0 29 72 117 14 328 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 0 25 85 204 14 429 Saginaw River at Weadock Road at Essexville, Mich. 04157065 156 0 24 72 194 13 630 Au Sable River near Au Sable, Mich. 04137500 161 0 4.9 6 34 14 631 Thunder Bay at Alpena, Mich. 04135020 74 0 5 7 14 14 332 Black River near Port Huron, Mich. 04160055 48 0 14 51 82 8 4
Appendix 1 39

Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued[USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus]

Watershed 

number Station name

USGS 

station 

number

Number of 

samples 

collected

Number of 

censored 

results

Trend 

test 

used

Trend in 

constituent 

units per 

year

Trend as a 

percent per 

year

p-value of 

trend

Chloride (mg/L)—Continued

1 Ontonagon River at Ontonagon, Mich. 04040018 70 0 SK 0.0241 0.803 0.2052 Menominee River at Menominee, Mich. 04067648 87 0 SK 0.1963 2.805 0.0133 Escanaba River at Wells, Mich. 040590345 91 1 SK 0.0697 0.332 0.7274 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 79 0 SK 0.0128 0.642 0.1735 Manistique River Above Manistique, Mich. 04057004 92 0 SK 0.0309 1.403 0.0296 Tahquamenon River at Emerson, Mich. 04045510 84 0 SK -0.0066 -0.330 0.5207 Pine River near Charles, Mich. 04127925 71 0 SK 0.0221 0.849 0.5708 Cheboygan River at Cheboygan, Mich. 04132052 74 0 SK 0.0940 1.176 0.1529 Boardman River near Traverse City, Mich. 04127200 76 0 SK 0.0079 0.099 0.585

10 Manistee River at Parkdale, Mich. 04126010 71 0 SK 0.1822 1.518 0.153

11 Pere Marquette River at Scottville, Mich. 04122500 91 0 SK 0.0726 0.605 0.249

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 173 0 SK 0.0403 0.212 0.61813 Muskegon River near Hersey, Mich. (upper) 04121621 80 0 SK 0.1073 0.651 0.37114 Grand River near Eastmanville, Mich. (lower) 04119400 175 0 SK 0.0456 0.086 0.80715 Grand River at Ionia, Mich. (upper) 04116000 80 3 SK 0.4895 1.030 0.21616 Kalamazoo River at New Richmond, Mich. (lower) 04108660 175 0 SK 0.2306 0.524 0.22017 Kalamazoo River near Augusta, Mich. (upper) 04105707 79 0 SK -0.1029 -0.264 0.09918 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 91 0 SK 0.2789 0.900 0.02419 St. Joseph River at Mottville, Mich. (upper) 04099000 74 0 SK 0.0422 0.184 0.50320 River Raisin at Monroe, Mich. 04176540 79 0 SK -0.3517 -0.782 0.59221 Huron River at Rockwood, Mich. 04175120 79 0 SK -0.0465 -0.049 0.97822 River Rouge at River Rouge, Mich. 04168550 74 1 SK 3.1247 3.396 0.04523 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 162 0 SK 0.8418 0.526 0.49324 Black River at Port Huron, Mich. 04160075 23 0 SK 1.8991 5.426 0.04725 Flint River near Fosters, Mich. 04149000 79 0 SK 0.0595 0.076 0.91626 Cass River near Bridgeport, Mich. 04152002 79 0 SK -0.7156 -1.704 0.03627 Shiawassee River near Fergus, Mich. 04145000 75 0 SK 0.1829 0.277 0.57128 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 0 SK 0.4450 0.536 0.50429 Saginaw River at Weadock Road at Essexville, Mich. 04157065 156 0 SK -0.0297 -0.040 1.00030 Au Sable River near Au Sable, Mich. 04137500 161 0 SK NA NA 0.10831 Thunder Bay at Alpena, Mich. 04135020 74 0 SK -0.0559 -0.799 0.10732 Black River near Port Huron, Mich. 04160055 48 0 SK 0.2563 0.545 1.000
40 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued [USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus] Watershed number Station name USGS station number Number of samples collected Number of censored results Minimum concentration Median concentration Maximum concentration Years of data used Seasons used Chromium (μg/L)

1 Ontonagon River at Ontonagon, Mich. 04040018 69 0 0.331 1.16 47.7 14 22 Menominee River at Menominee, Mich. 04067648 86 1 0.057 0.41 1.51 14 33 Escanaba River at Wells, Mich. 040590345 89 0 0.129 0.658 2.22 15 34 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 76 0 0.102 0.452 1.23 14 65 Manistique River Above Manistique, Mich. 04057004 91 0 0.095 0.42 1.18 15 36 Tahquamenon River at Emerson, Mich. 04045510 83 1 0.057 0.424 1.26 15 37 Pine River near Charles, Mich. 04127925 71 0 0.543 1.42 8.08 14 38 Cheboygan River at Cheboygan, Mich. 04132052 70 20 0.002 0.1075 1.09 14 NA9 Boardman River near Traverse City, Mich. 04127200 75 14 0.002 0.214 1.76 13 NA

10 Manistee River at Parkdale, Mich. 04126010 70 2 0.04 0.29 1.14 14 3

11 Pere Marquette River at Scottville, Mich. 04122500 88 2 0.057 0.433 2.49 15 3

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 168 17 0.002 0.2805 7.14 15 NA13 Muskegon River near Hersey, Mich. (upper) 04121621 77 4 0.002 0.34 2.84 14 414 Grand River near Eastmanville, Mich. (lower) 04119400 171 0 0.147 1.12 4.73 15 1215 Grand River at Ionia, Mich. (upper) 04116000 77 0 0.112 0.764 15.1 14 316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 171 2 0.057 0.718 5.97 15 1217 Kalamazoo River near Augusta, Mich. (upper) 04105707 78 0 0.105 1.11 6.1 14 418 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 86 1 0.057 0.6305 3.87 15 319 St. Joseph River at Mottville, Mich. (upper) 04099000 71 7 0.002 0.182 1.89 14 NA20 River Raisin at Monroe, Mich. 04176540 78 0 0.156 0.7535 6.75 14 421 Huron River at Rockwood, Mich. 04175120 78 0 0.136 0.5565 2.33 14 422 River Rouge at River Rouge, Mich. 04168550 71 0 0.563 1.39 4.38 14 323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 158 0 0.275 1.53 14.7 14 1224 Black River at Port Huron, Mich. 04160075 21 0 0.146 0.643 1.25 6 325 Flint River near Fosters, Mich. 04149000 78 0 0.358 1.25 10 14 326 Cass River near Bridgeport, Mich. 04152002 78 0 0.187 0.9 4.05 14 627 Shiawassee River near Fergus, Mich. 04145000 70 0 0.132 0.6885 3.28 14 328 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 77 0 0.057 0.54 3.37 14 429 Saginaw River at Weadock Road at Essexville, Mich. 04157065 151 0 0.14 0.978 7.3 13 630 Au Sable River near Au Sable, Mich. 04137500 159 59 0.002 0.09 1.2 14 NA31 Thunder Bay at Alpena, Mich. 04135020 71 22 0.002 0.11 1.6 14 NA32 Black River near Port Huron, Mich. 04160055 48 0 0.292 0.962 10.2 8 4
Appendix 1 41

Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued[USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus]

Watershed 

number Station name

USGS 

station 

number

Number of 

samples 

collected

Number of 

censored 

results

Trend 

test 

used

Trend in 

constituent 

units per 

year

Trend as a 

percent per 

year

p-value of 

trend

Chromium (μg/L)—Continued

1 Ontonagon River at Ontonagon, Mich. 04040018 69 0 SK 0.0407 2.866 0.1312 Menominee River at Menominee, Mich. 04067648 86 1 SK 0.0197 4.650 0.0453 Escanaba River at Wells, Mich. 040590345 89 0 SK 0.0125 2.088 0.4584 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 76 0 SK 0.0321 7.158 0.0125 Manistique River Above Manistique, Mich. 04057004 91 0 SK 0.0177 4.178 0.0486 Tahquamenon River at Emerson, Mich. 04045510 83 1 SK 0.0136 2.995 0.1377 Pine River near Charles, Mich. 04127925 71 0 SK 0.0059 0.437 0.8098 Cheboygan River at Cheboygan, Mich. 04132052 70 20 TR 0.0344 16.808 <0.00019 Boardman River near Traverse City, Mich. 04127200 75 14 TR 0.0720 23.518 <0.0001

10 Manistee River at Parkdale, Mich. 04126010 70 2 SK 0.0188 5.953 0.141

11 Pere Marquette River at Scottville, Mich. 04122500 88 2 SK 0.0102 2.484 0.581

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 168 17 TR 0.0224 5.649 0.00113 Muskegon River near Hersey, Mich. (upper) 04121621 77 4 SK 0.0217 7.217 0.06014 Grand River near Eastmanville, Mich. (lower) 04119400 171 0 SK -0.0032 -0.312 0.89515 Grand River at Ionia, Mich. (upper) 04116000 77 0 SK 0.0198 2.905 0.18916 Kalamazoo River at New Richmond, Mich. (lower) 04108660 171 2 SK 0.0096 1.371 0.48317 Kalamazoo River near Augusta, Mich. (upper) 04105707 78 0 SK 0.0054 0.463 0.75218 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 86 1 SK -0.0050 -0.833 0.73719 St. Joseph River at Mottville, Mich. (upper) 04099000 71 7 TR 0.0433 12.720 0.00120 River Raisin at Monroe, Mich. 04176540 78 0 SK 0.0215 2.959 0.38121 Huron River at Rockwood, Mich. 04175120 78 0 SK 0.0221 3.960 0.23022 River Rouge at River Rouge, Mich. 04168550 71 0 SK -0.0335 -2.412 0.32023 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 158 0 SK -0.0270 -1.865 0.38124 Black River at Port Huron, Mich. 04160075 21 0 SK -0.0079 -1.071 0.90225 Flint River near Fosters, Mich. 04149000 78 0 SK -0.0190 -1.399 0.43726 Cass River near Bridgeport, Mich. 04152002 78 0 SK -0.0026 -0.327 0.77427 Shiawassee River near Fergus, Mich. 04145000 70 0 SK 0.0013 0.187 1.00028 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 77 0 SK 0.0069 1.306 0.66129 Saginaw River at Weadock Road at Essexville, Mich. 04157065 151 0 SK -0.0122 -1.416 0.41530 Au Sable River near Au Sable, Mich. 04137500 159 59 TR 0.0504 26.731 <0.000131 Thunder Bay at Alpena, Mich. 04135020 71 22 TR 0.0450 18.854 <0.000132 Black River near Port Huron, Mich. 04160055 48 0 SK 0.0135 1.323 0.658
42 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued [USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus] Watershed number Station name USGS station number Number of samples collected Number of censored results Minimum concentration Median concentration Maximum concentration Years of data used Seasons used Copper (μg/L)

1 Ontonagon River at Ontonagon, Mich. 04040018 70 0 1.12 3.26 46.9 14 22 Menominee River at Menominee, Mich. 04067648 87 0 0.489 0.815 1.64 14 33 Escanaba River at Wells, Mich. 040590345 90 0 0.452 0.6805 2.33 15 34 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 76 0 0.21 0.414 1.57 14 65 Manistique River Above Manistique, Mich. 04057004 91 0 0.06 0.374 0.677 15 36 Tahquamenon River at Emerson, Mich. 04045510 82 0 0.202 0.4025 0.982 15 37 Pine River near Charles, Mich. 04127925 68 0 0.579 1.265 6.12 14 38 Cheboygan River at Cheboygan, Mich. 04132052 70 0 0.27 0.52 0.969 14 39 Boardman River near Traverse City, Mich. 04127200 71 0 0.124 0.318 1.51 13 4

10 Manistee River at Parkdale, Mich. 04126010 70 0 0.223 0.4565 0.803 14 3

11 Pere Marquette River at Scottville, Mich. 04122500 90 0 0.241 0.485 2.05 15 3

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 168 0 0.338 0.6735 6.67 15 1213 Muskegon River near Hersey, Mich. (upper) 04121621 78 0 0.34 0.6065 2.8 14 414 Grand River near Eastmanville, Mich. (lower) 04119400 172 0 1.13 2.345 393 15 1215 Grand River at Ionia, Mich. (upper) 04116000 78 0 1.24 2.36 12.4 14 316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 171 0 0.806 1.44 5.03 15 1217 Kalamazoo River near Augusta, Mich. (upper) 04105707 77 0 0.624 1.38 4.25 14 418 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 88 0 0.865 1.52 4.92 15 319 St. Joseph River at Mottville, Mich. (upper) 04099000 71 1 0.03 0.666 1.41 14 320 River Raisin at Monroe, Mich. 04176540 79 0 1.47 2.39 7.98 14 421 Huron River at Rockwood, Mich. 04175120 78 0 0.898 1.635 3.63 14 422 River Rouge at River Rouge, Mich. 04168550 73 0 0.793 2.75 7.21 14 323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 160 0 1.82 3.665 19.8 14 1224 Black River at Port Huron, Mich. 04160075 20 0 1.18 2.2 4.08 6 325 Flint River near Fosters, Mich. 04149000 78 0 1.41 2.58 13.5 14 326 Cass River near Bridgeport, Mich. 04152002 78 0 1.15 1.915 3.93 14 627 Shiawassee River near Fergus, Mich. 04145000 73 0 1.05 1.68 4.28 14 328 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 78 0 0.998 1.78 5.52 14 429 Saginaw River at Weadock Road at Essexville, Mich. 04157065 152 0 1.45 2.16 8.14 13 630 Au Sable River near Au Sable, Mich. 04137500 154 0 0.11 0.254 1.23 14 631 Thunder Bay at Alpena, Mich. 04135020 70 1 0.001 0.392 0.834 14 332 Black River near Port Huron, Mich. 04160055 48 0 0.665 2.08 9.4 8 4
Appendix 1 43

Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued[USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus]

Watershed 

number Station name

USGS 

station 

number

Number of 

samples 

collected

Number of 

censored 

results

Trend 

test 

used

Trend in 

constituent 

units per 

year

Trend as a 

percent per 

year

p-value of 

trend

Copper (μg/L)—Continued

1 Ontonagon River at Ontonagon, Mich. 04040018 70 0 SK 0.0313 0.920 0.4782 Menominee River at Menominee, Mich. 04067648 87 0 SK -0.0041 -0.493 0.5973 Escanaba River at Wells, Mich. 040590345 90 0 SK -0.0223 -3.315 0.0024 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 76 0 SK 0.0067 1.609 0.0605 Manistique River Above Manistique, Mich. 04057004 91 0 SK 0.0065 1.736 0.0576 Tahquamenon River at Emerson, Mich. 04045510 82 0 SK 0.0075 1.593 0.2027 Pine River near Charles, Mich. 04127925 68 0 SK -0.0045 -0.356 0.6648 Cheboygan River at Cheboygan, Mich. 04132052 70 0 SK -0.0083 -1.614 0.0669 Boardman River near Traverse City, Mich. 04127200 71 0 SK 0.0125 3.912 0.060

10 Manistee River at Parkdale, Mich. 04126010 70 0 SK 0.0070 1.547 0.327

11 Pere Marquette River at Scottville, Mich. 04122500 90 0 SK -0.0018 -0.373 0.859

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 168 0 SK 0.0061 0.906 0.28613 Muskegon River near Hersey, Mich. (upper) 04121621 78 0 SK 0.0019 0.327 0.92714 Grand River near Eastmanville, Mich. (lower) 04119400 172 0 SK -0.0278 -1.230 0.07215 Grand River at Ionia, Mich. (upper) 04116000 78 0 SK -0.0465 -2.004 0.10316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 171 0 SK -0.0193 -1.365 0.02117 Kalamazoo River near Augusta, Mich. (upper) 04105707 77 0 SK -0.0463 -3.352 0.10218 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 88 0 SK -0.0084 -0.575 0.55519 St. Joseph River at Mottville, Mich. (upper) 04099000 71 1 SK 0.0052 0.789 0.62420 River Raisin at Monroe, Mich. 04176540 79 0 SK -0.0501 -2.320 0.01021 Huron River at Rockwood, Mich. 04175120 78 0 SK -0.0185 -1.136 0.24922 River Rouge at River Rouge, Mich. 04168550 73 0 SK -0.0491 -1.851 0.16323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 160 0 SK -0.0811 -2.311 0.02224 Black River at Port Huron, Mich. 04160075 20 0 SK 0.0888 3.886 0.61025 Flint River near Fosters, Mich. 04149000 78 0 SK -0.0470 -1.823 0.07526 Cass River near Bridgeport, Mich. 04152002 78 0 SK -0.0262 -1.417 0.24427 Shiawassee River near Fergus, Mich. 04145000 73 0 SK -0.0034 -0.197 0.75128 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 78 0 SK -0.0116 -0.637 0.69629 Saginaw River at Weadock Road at Essexville, Mich. 04157065 152 0 SK -0.0202 -0.965 0.10930 Au Sable River near Au Sable, Mich. 04137500 154 0 SK 0.0003 0.137 0.93131 Thunder Bay at Alpena, Mich. 04135020 70 1 SK 0.0073 2.040 0.48732 Black River near Port Huron, Mich. 04160055 48 0 SK 0.0147 0.623 0.461
44 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued [USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus] Watershed number Station name USGS station number Number of samples collected Number of censored results Minimum concentration Median concentration Maximum concentration Years of data used Seasons used Lead (μg/L)

1 Ontonagon River at Ontonagon, Mich. 04040018 70 0 0.0605 0.235 16.9 14 22 Menominee River at Menominee, Mich. 04067648 85 0 0.0483 0.125 0.871 14 33 Escanaba River at Wells, Mich. 040590345 89 0 0.0996 0.159 0.765 15 34 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 78 0 0.0204 0.177 0.552 14 65 Manistique River Above Manistique, Mich. 04057004 92 0 0.0464 0.1595 0.407 15 36 Tahquamenon River at Emerson, Mich. 04045510 84 0 0.031 0.193 0.583 15 37 Pine River near Charles, Mich. 04127925 71 0 0.201 0.516 4.17 14 38 Cheboygan River at Cheboygan, Mich. 04132052 72 0 0.0127 0.03835 0.408 14 39 Boardman River near Traverse City, Mich. 04127200 75 0 0.0177 0.0824 1.48 13 4

10 Manistee River at Parkdale, Mich. 04126010 70 0 0.072 0.164 0.7 14 3

11 Pere Marquette River at Scottville, Mich. 04122500 89 0 0.0514 0.29 1.47 15 3

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 173 0 0.0406 0.147 8.34 15 1213 Muskegon River near Hersey, Mich. (upper) 04121621 79 0 0.053 0.194 3.35 14 414 Grand River near Eastmanville, Mich. (lower) 04119400 175 0 0.187 1.02 5.53 15 1215 Grand River at Ionia, Mich. (upper) 04116000 79 0 0.255 0.817 18 14 316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 175 0 0.387 1.19 7.87 15 1217 Kalamazoo River near Augusta, Mich. (upper) 04105707 79 0 0.22 1.01 7.01 14 418 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 91 0 0.183 0.709 5.2 15 319 St. Joseph River at Mottville, Mich. (upper) 04099000 74 1 0.0041 0.2635 1.4 14 320 River Raisin at Monroe, Mich. 04176540 79 0 0.232 0.566 8.37 14 421 Huron River at Rockwood, Mich. 04175120 79 0 0.363 1.43 2.84 14 422 River Rouge at River Rouge, Mich. 04168550 74 0 0.112 2.055 7.09 14 323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 161 0 0.377 1.63 21.1 14 1224 Black River at Port Huron, Mich. 04160075 23 0 0.218 0.559 1.66 6 325 Flint River near Fosters, Mich. 04149000 79 0 0.311 1.47 16.9 14 326 Cass River near Bridgeport, Mich. 04152002 79 0 0.175 0.607 3.32 14 627 Shiawassee River near Fergus, Mich. 04145000 74 0 0.108 0.557 3.91 14 328 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 0 0.102 0.363 2.53 14 429 Saginaw River at Weadock Road at Essexville, Mich. 04157065 156 0 0.359 0.9455 8.87 13 630 Au Sable River near Au Sable, Mich. 04137500 160 0 0.0145 0.0371 0.199 14 631 Thunder Bay at Alpena, Mich. 04135020 72 0 0.0401 0.08475 0.251 14 332 Black River near Port Huron, Mich. 04160055 48 0 0.169 0.55 12.8 8 4
Appendix 1 45

Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued[USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus]

Watershed 

number Station name

USGS 

station 

number

Number of 

samples 

collected

Number of 

censored 

results

Trend 

test 

used

Trend in 

constituent 

units per 

year

Trend as a 

percent per 

year

p-value of 

trend

Lead (μg/L)—Continued

1 Ontonagon River at Ontonagon, Mich. 04040018 70 0 SK 0.0123 3.832 0.0162 Menominee River at Menominee, Mich. 04067648 85 0 SK -0.0024 -1.802 0.0243 Escanaba River at Wells, Mich. 040590345 89 0 SK 0.0017 0.920 0.2174 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 78 0 SK 0.0027 1.362 0.5105 Manistique River Above Manistique, Mich. 04057004 92 0 SK 0.0013 0.707 0.4496 Tahquamenon River at Emerson, Mich. 04045510 84 0 SK 0.0028 1.160 0.4017 Pine River near Charles, Mich. 04127925 71 0 SK -0.0058 -1.085 0.5488 Cheboygan River at Cheboygan, Mich. 04132052 72 0 SK <0.0001 <0.0001 1.0009 Boardman River near Traverse City, Mich. 04127200 75 0 SK 0.0008 0.980 0.792

10 Manistee River at Parkdale, Mich. 04126010 70 0 SK -0.0029 -1.790 0.076

11 Pere Marquette River at Scottville, Mich. 04122500 89 0 SK -0.0043 -1.687 0.412

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 173 0 SK -0.0011 -0.729 0.31613 Muskegon River near Hersey, Mich. (upper) 04121621 79 0 SK -0.0056 -3.131 0.25514 Grand River near Eastmanville, Mich. (lower) 04119400 175 0 SK -0.0478 -4.970 0.00815 Grand River at Ionia, Mich. (upper) 04116000 79 0 SK -0.0245 -3.214 0.17116 Kalamazoo River at New Richmond, Mich. (lower) 04108660 175 0 SK -0.0279 -2.332 0.01017 Kalamazoo River near Augusta, Mich. (upper) 04105707 79 0 SK -0.0487 -4.818 0.09218 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 91 0 SK -0.0434 -6.263 0.00519 St. Joseph River at Mottville, Mich. (upper) 04099000 74 1 SK -0.0041 -1.688 0.16620 River Raisin at Monroe, Mich. 04176540 79 0 SK -0.0146 -2.574 0.09921 Huron River at Rockwood, Mich. 04175120 79 0 SK -0.0360 -2.520 0.12522 River Rouge at River Rouge, Mich. 04168550 74 0 SK -0.0652 -3.276 0.17123 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 161 0 SK -0.0589 -3.912 0.02624 Black River at Port Huron, Mich. 04160075 23 0 SK 0.0044 0.793 0.55925 Flint River near Fosters, Mich. 04149000 79 0 SK -0.0931 -5.383 0.03226 Cass River near Bridgeport, Mich. 04152002 79 0 SK -0.0297 -5.446 0.00927 Shiawassee River near Fergus, Mich. 04145000 74 0 SK -0.0035 -0.647 0.72128 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 0 SK -0.0202 -5.484 0.02629 Saginaw River at Weadock Road at Essexville, Mich. 04157065 156 0 SK -0.0452 -5.271 0.00530 Au Sable River near Au Sable, Mich. 04137500 160 0 SK -0.0009 -2.547 0.16431 Thunder Bay at Alpena, Mich. 04135020 72 0 SK -0.0015 -1.574 0.15432 Black River near Port Huron, Mich. 04160055 48 0 SK 0.0289 4.928 0.184
46 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued [USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus] Watershed number Station name USGS station number Number of samples collected Number of censored results Minimum concentration Median concentration Maximum concentration Years of data used Seasons used Mercury (ng/L)

1 Ontonagon River at Ontonagon, Mich. 04040018 69 1 0.1 2.28 45.05 14 22 Menominee River at Menominee, Mich. 04067648 87 1 0.1 2.48 12.1 14 33 Escanaba River at Wells, Mich. 040590345 91 1 0.1 2.76 55.357 15 34 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 78 0 0.69 2.755 9.68 14 65 Manistique River Above Manistique, Mich. 04057004 90 0 0.49 2.215 8.24 15 36 Tahquamenon River at Emerson, Mich. 04045510 82 0 0.63 3.985 9.632 15 37 Pine River near Charles, Mich. 04127925 70 0 0.2 3.98 17.76 14 38 Cheboygan River at Cheboygan, Mich. 04132052 73 1 0.14 0.43 1.43 14 39 Boardman River near Traverse City, Mich. 04127200 75 1 0.14 0.82 9.34 13 4

10 Manistee River at Parkdale, Mich. 04126010 69 0 0.28 0.95 3.39 14 3

11 Pere Marquette River at Scottville, Mich. 04122500 91 0 0.46 1.89 7.07 15 3

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 169 0 0.23 1.1 34.004 15 1213 Muskegon River near Hersey, Mich. (upper) 04121621 79 0 0.57 1.7 19.33 14 414 Grand River near Eastmanville, Mich. (lower) 04119400 172 0 0.66 3.45 21.813 15 1215 Grand River at Ionia, Mich. (upper) 04116000 78 0 0.58 2.78 52.23 14 316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 172 0 1.09 5.225 15.14 15 1217 Kalamazoo River near Augusta, Mich. (upper) 04105707 77 0 0.98 4.23 304.3 14 418 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 90 0 0.79 3.06 15.98 15 319 St. Joseph River at Mottville, Mich. (upper) 04099000 74 1 0.14 1.335 7.89 14 320 River Raisin at Monroe, Mich. 04176540 78 0 0.94 1.8 21.6 14 421 Huron River at Rockwood, Mich. 04175120 79 0 0.4 1.55 5.73 14 422 River Rouge at River Rouge, Mich. 04168550 74 0 0.4 3.285 15.2 14 323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 161 1 0.1 3.59 40.69 14 1224 Black River at Port Huron, Mich. 04160075 22 0 0.28 1.185 6.52 6 325 Flint River near Fosters, Mich. 04149000 79 0 0.76 3.16 29.71 14 326 Cass River near Bridgeport, Mich. 04152002 79 0 1 2.05 12.45 14 627 Shiawassee River near Fergus, Mich. 04145000 74 0 0.59 1.89 12.53 14 328 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 0 0.48 1.86 8.01 14 429 Saginaw River at Weadock Road at Essexville, Mich. 04157065 156 0 0.4 2.19 42.2 13 630 Au Sable River near Au Sable, Mich. 04137500 162 8 0.01 0.35 2.54 14 631 Thunder Bay at Alpena, Mich. 04135020 73 0 0.21 0.6 2.58 14 332 Black River near Port Huron, Mich. 04160055 48 0 0.55 1.625 32.64 8 4
Appendix 1 47

Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued[USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus]

Watershed 

number Station name

USGS 

station 

number

Number of 

samples 

collected

Number of 

censored 

results

Trend 

test 

used

Trend in 

constituent 

units per 

year

Trend as a 

percent per 

year

p-value of 

trend

Mercury (ng/L)—Continued

1 Ontonagon River at Ontonagon, Mich. 04040018 69 1 SK 0.1961 5.554 0.0802 Menominee River at Menominee, Mich. 04067648 87 1 SK -0.0252 -0.987 0.5063 Escanaba River at Wells, Mich. 040590345 91 1 SK 0.0198 0.724 0.7974 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 78 0 SK 0.1500 5.209 0.0055 Manistique River Above Manistique, Mich. 04057004 90 0 SK 0.1200 4.459 0.0766 Tahquamenon River at Emerson, Mich. 04045510 82 0 SK 0.0799 1.521 0.1877 Pine River near Charles, Mich. 04127925 70 0 SK 0.1289 2.991 0.0238 Cheboygan River at Cheboygan, Mich. 04132052 73 1 SK 0.0306 7.117 0.0049 Boardman River near Traverse City, Mich. 04127200 75 1 SK 0.0122 1.529 0.590

10 Manistee River at Parkdale, Mich. 04126010 69 0 SK -0.0212 -2.099 0.277

11 Pere Marquette River at Scottville, Mich. 04122500 91 0 SK -0.0101 -0.566 0.690

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 169 0 SK -0.0032 -0.295 0.77713 Muskegon River near Hersey, Mich. (upper) 04121621 79 0 SK <0.0001 <0.0001 1.00014 Grand River near Eastmanville, Mich. (lower) 04119400 172 0 SK -0.0829 -2.522 0.09715 Grand River at Ionia, Mich. (upper) 04116000 78 0 SK -0.0293 -1.061 0.59416 Kalamazoo River at New Richmond, Mich. (lower) 04108660 172 0 SK -0.0854 -1.631 0.19417 Kalamazoo River near Augusta, Mich. (upper) 04105707 77 0 SK -0.0801 -1.989 0.50718 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 90 0 SK -0.0760 -2.647 0.12819 St. Joseph River at Mottville, Mich. (upper) 04099000 74 1 SK 0.0170 1.419 0.20020 River Raisin at Monroe, Mich. 04176540 78 0 SK -0.0114 -0.688 0.51121 Huron River at Rockwood, Mich. 04175120 79 0 SK 0.0219 1.563 0.45422 River Rouge at River Rouge, Mich. 04168550 74 0 SK -0.0825 -2.723 0.40923 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 161 1 SK -0.0916 -2.960 0.08624 Black River at Port Huron, Mich. 04160075 22 0 SK 0.1016 7.415 0.41425 Flint River near Fosters, Mich. 04149000 79 0 SK -0.1229 -3.128 0.27026 Cass River near Bridgeport, Mich. 04152002 79 0 SK -0.0570 -2.916 0.26727 Shiawassee River near Fergus, Mich. 04145000 74 0 SK 0.0343 1.836 0.24228 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 0 SK -0.0354 -1.925 0.30829 Saginaw River at Weadock Road at Essexville, Mich. 04157065 156 0 SK -0.0417 -2.152 0.06830 Au Sable River near Au Sable, Mich. 04137500 162 8 SK 0.0115 3.432 0.04231 Thunder Bay at Alpena, Mich. 04135020 73 0 SK 0.0167 2.692 0.20732 Black River near Port Huron, Mich. 04160055 48 0 SK 0.0462 2.299 0.461
48 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued [USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus] Watershed number Station name USGS station number Number of samples collected Number of censored results Minimum concentration Median concentration Maximum concentration Years of data used Seasons used Nitrate (mg/L as N)

1 Ontonagon River at Ontonagon, Mich. 04040018 64 23 0.001 0.01 0.21 14 NA2 Menominee River at Menominee, Mich. 04067648 81 13 0.002 0.053 0.27 14 NA3 Escanaba River at Wells, Mich. 040590345 91 1 0.01 0.113 0.49 15 34 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 75 2 0.006 0.063 0.36 14 65 Manistique River Above Manistique, Mich. 04057004 88 1 0.01 0.0495 0.3 15 36 Tahquamenon River at Emerson, Mich. 04045510 82 0 0.012 0.071 0.119 15 37 Pine River near Charles, Mich. 04127925 67 10 0.001 0.02 0.16 14 NA8 Cheboygan River at Cheboygan, Mich. 04132052 71 5 0.001 0.025 0.143 14 NA9 Boardman River near Traverse City, Mich. 04127200 76 0 0.134 0.2 0.41 13 4

10 Manistee River at Parkdale, Mich. 04126010 71 0 0.062 0.147 0.3 14 3

11 Pere Marquette River at Scottville, Mich. 04122500 91 0 0.04 0.106 0.52 15 3

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 173 0 0.042 0.3 0.71 15 1213 Muskegon River near Hersey, Mich. (upper) 04121621 80 0 0.027 0.2 1.61 14 414 Grand River near Eastmanville, Mich. (lower) 04119400 175 0 0.21 1.49 5.16 15 1215 Grand River at Ionia, Mich. (upper) 04116000 80 3 0.01 1.72 6.4 14 316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 175 0 0.3 1.03 2.86 15 1217 Kalamazoo River near Augusta, Mich. (upper) 04105707 79 0 0.55 0.99 2.38 14 418 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 91 0 0.68 1.49 4.3 15 319 St. Joseph River at Mottville, Mich. (upper) 04099000 74 0 0.73 1.32 2.4 14 320 River Raisin at Monroe, Mich. 04176540 79 4 0.003 1.38 10.9 14 421 Huron River at Rockwood, Mich. 04175120 79 2 0.01 0.28 1.48 14 422 River Rouge at River Rouge, Mich. 04168550 74 1 0.01 0.78 1.61 14 323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 162 0 0.58 1.565 4.7 14 1224 Black River at Port Huron, Mich. 04160075 23 0 0.026 1.03 7.46 6 325 Flint River near Fosters, Mich. 04149000 79 0 0.62 2.12 5.8 14 326 Cass River near Bridgeport, Mich. 04152002 78 1 0.01 1.86 7.1 14 627 Shiawassee River near Fergus, Mich. 04145000 75 0 0.181 0.72 4.4 14 328 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 0 0.24 0.74 3.2 14 429 Saginaw River at Weadock Road at Essexville, Mich. 04157065 155 0 0.19 1.39 4.88 13 630 Au Sable River near Au Sable, Mich. 04137500 157 33 0.001 0.012 0.155 14 NA31 Thunder Bay at Alpena, Mich. 04135020 72 11 0.002 0.015 0.29 14 NA32 Black River near Port Huron, Mich. 04160055 47 9 0.001 0.44 9.9 8 NA
Appendix 1 49

Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued[USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus]

Watershed 

number Station name

USGS 

station 

number

Number of 

samples 

collected

Number of 

censored 

results

Trend 

test 

used

Trend in 

constituent 

units per 

year

Trend as a 

percent per 

year

p-value of 

trend

Nitrate (mg/L as N)—Continued

1 Ontonagon River at Ontonagon, Mich. 04040018 64 23 TR -0.0008 -2.711 0.4832 Menominee River at Menominee, Mich. 04067648 81 13 TR 0.0021 3.197 0.2973 Escanaba River at Wells, Mich. 040590345 91 1 SK 0.0033 2.818 0.1004 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 75 2 SK -0.0006 -0.940 0.5695 Manistique River Above Manistique, Mich. 04057004 88 1 SK -0.0011 -2.293 0.3776 Tahquamenon River at Emerson, Mich. 04045510 82 0 SK -0.0013 -1.797 0.1227 Pine River near Charles, Mich. 04127925 67 10 TR -0.0005 -1.968 0.5718 Cheboygan River at Cheboygan, Mich. 04132052 71 5 TR -0.0009 -2.781 0.1959 Boardman River near Traverse City, Mich. 04127200 76 0 SK 0.0018 0.873 0.199

10 Manistee River at Parkdale, Mich. 04126010 71 0 SK -0.0034 -2.169 0.034

11 Pere Marquette River at Scottville, Mich. 04122500 91 0 SK 0.0021 1.735 0.528

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 173 0 SK -0.0033 -1.148 0.06013 Muskegon River near Hersey, Mich. (upper) 04121621 80 0 SK -0.0027 -1.281 0.11314 Grand River near Eastmanville, Mich. (lower) 04119400 175 0 SK -0.0120 -0.819 0.36915 Grand River at Ionia, Mich. (upper) 04116000 80 3 SK -0.0486 -2.665 0.14616 Kalamazoo River at New Richmond, Mich. (lower) 04108660 175 0 SK -0.0248 -2.480 0.05817 Kalamazoo River near Augusta, Mich. (upper) 04105707 79 0 SK -0.0136 -1.384 0.28918 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 91 0 SK <0.0001 <0.0001 1.00019 St. Joseph River at Mottville, Mich. (upper) 04099000 74 0 SK -0.0223 -1.654 0.04620 River Raisin at Monroe, Mich. 04176540 79 4 SK -0.0560 -6.361 0.18621 Huron River at Rockwood, Mich. 04175120 79 2 SK -0.0202 -7.487 0.00722 River Rouge at River Rouge, Mich. 04168550 74 1 SK 0.0347 3.896 0.02823 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 162 0 SK 0.0006 0.036 0.92824 Black River at Port Huron, Mich. 04160075 23 0 SK -0.1102 -7.345 0.55925 Flint River near Fosters, Mich. 04149000 79 0 SK -0.0323 -1.593 0.21326 Cass River near Bridgeport, Mich. 04152002 78 1 SK -0.0300 -1.959 0.49627 Shiawassee River near Fergus, Mich. 04145000 75 0 SK 0.0319 3.013 0.24728 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 0 SK 0.0250 3.145 0.39829 Saginaw River at Weadock Road at Essexville, Mich. 04157065 155 0 SK -0.0414 -3.092 0.07230 Au Sable River near Au Sable, Mich. 04137500 157 33 TR -0.0014 -3.653 0.01031 Thunder Bay at Alpena, Mich. 04135020 72 11 TR -0.0006 -2.362 0.36532 Black River near Port Huron, Mich. 04160055 47 9 TR 0.0808 4.600 0.701
50 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued [USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus] Watershed number Station name USGS station number Number of samples collected Number of censored results Minimum concentration Median concentration Maximum concentration Years of data used Seasons used Nitrite (mg/L as N)

1 Ontonagon River at Ontonagon, Mich. 04040018 70 24 0.001 0.008 0.16 14 NA2 Menominee River at Menominee, Mich. 04067648 87 39 0.001 0.004 0.016 14 NA3 Escanaba River at Wells, Mich. 040590345 91 17 0.004 0.012 0.058 15 NA4 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 79 36 0.001 0.005 0.05 14 NA5 Manistique River Above Manistique, Mich. 04057004 92 42 0.002 0.004 0.0095 15 NA6 Tahquamenon River at Emerson, Mich. 04045510 84 45 0.001 0.005 0.011 15 NA7 Pine River near Charles, Mich. 04127925 71 25 0.003 0.009 0.031 14 NA8 Cheboygan River at Cheboygan, Mich. 04132052 73 37 0.001 0.002 0.009 14 NA9 Boardman River near Traverse City, Mich. 04127200 76 47 0.002 0.003 0.0095 13 NA

10 Manistee River at Parkdale, Mich. 04126010 71 45 0.002 0.005 0.009 14 NA

11 Pere Marquette River at Scottville, Mich. 04122500 91 44 0.002 0.004 0.021 15 NA

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 173 66 0.003 0.007 0.022 15 NA13 Muskegon River near Hersey, Mich. (upper) 04121621 80 34 0.002 0.006 0.012 14 NA14 Grand River near Eastmanville, Mich. (lower) 04119400 175 0 0.013 0.029 0.102 15 1215 Grand River at Ionia, Mich. (upper) 04116000 80 6 0.007 0.02 0.108 14 NA16 Kalamazoo River at New Richmond, Mich. (lower) 04108660 175 1 0.009 0.018 0.087 15 1217 Kalamazoo River near Augusta, Mich. (upper) 04105707 79 11 0.005 0.011 0.07 14 NA18 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 91 7 0.007 0.013 0.039 15 NA19 St. Joseph River at Mottville, Mich. (upper) 04099000 74 1 0.009 0.015 0.033 14 320 River Raisin at Monroe, Mich. 04176540 79 10 0.002 0.014 0.087 14 NA21 Huron River at Rockwood, Mich. 04175120 79 16 0.003 0.011 0.037 14 NA22 River Rouge at River Rouge, Mich. 04168550 74 2 0.001 0.024 0.061 14 323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 162 0 0.009 0.0325 0.106 14 1224 Black River at Port Huron, Mich. 04160075 23 5 0.004 0.009 0.116 6 NA25 Flint River near Fosters, Mich. 04149000 79 5 0.007 0.02 0.1 14 NA26 Cass River near Bridgeport, Mich. 04152002 79 9 0.003 0.018 0.098 14 NA27 Shiawassee River near Fergus, Mich. 04145000 75 19 0.003 0.01 0.09 14 NA28 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 1 0.008 0.016 0.041 14 429 Saginaw River at Weadock Road at Essexville, Mich. 04157065 156 0 0.012 0.031 0.113 13 630 Au Sable River near Au Sable, Mich. 04137500 161 72 0.001 0.002 0.0085 14 NA31 Thunder Bay at Alpena, Mich. 04135020 73 43 0.001 0.003 0.009 14 NA32 Black River near Port Huron, Mich. 04160055 47 10 0.001 0.013 0.25 8 NA
Appendix 1 51

Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued[USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus]

Watershed 

number Station name

USGS 

station 

number

Number of 

samples 

collected

Number of 

censored 

results

Trend 

test 

used

Trend in 

constituent 

units per 

year

Trend as a 

percent per 

year

p-value of 

trend

Nitrite (mg/L as N)—Continued

1 Ontonagon River at Ontonagon, Mich. 04040018 70 24 None NA NA NA2 Menominee River at Menominee, Mich. 04067648 87 39 None NA NA NA3 Escanaba River at Wells, Mich. 040590345 91 17 None NA NA NA4 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 79 36 None NA NA NA5 Manistique River Above Manistique, Mich. 04057004 92 42 None NA NA NA6 Tahquamenon River at Emerson, Mich. 04045510 84 45 None NA NA NA7 Pine River near Charles, Mich. 04127925 71 25 TR 0.0002 2.119 0.1268 Cheboygan River at Cheboygan, Mich. 04132052 73 37 None NA NA NA9 Boardman River near Traverse City, Mich. 04127200 76 47 None NA NA NA

10 Manistee River at Parkdale, Mich. 04126010 71 45 None NA NA NA

11 Pere Marquette River at Scottville, Mich. 04122500 91 44 None NA NA NA

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 173 66 None NA NA NA13 Muskegon River near Hersey, Mich. (upper) 04121621 80 34 TR <0.0001 0.211 0.83614 Grand River near Eastmanville, Mich. (lower) 04119400 175 0 SK -0.0008 -2.663 0.04315 Grand River at Ionia, Mich. (upper) 04116000 80 6 TR -0.0002 -0.648 0.62616 Kalamazoo River at New Richmond, Mich. (lower) 04108660 175 1 SK -0.0003 -1.576 0.16417 Kalamazoo River near Augusta, Mich. (upper) 04105707 79 11 TR -0.0003 -2.179 0.15218 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 91 7 TR -0.0001 -0.712 0.38319 St. Joseph River at Mottville, Mich. (upper) 04099000 74 1 SK -0.0001 -0.702 0.31120 River Raisin at Monroe, Mich. 04176540 79 10 TR -0.0010 -4.833 0.00221 Huron River at Rockwood, Mich. 04175120 79 16 TR -0.0002 -1.456 0.27022 River Rouge at River Rouge, Mich. 04168550 74 2 SK 0.0015 6.400 0.03223 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 162 0 SK -0.0013 -3.912 0.02124 Black River at Port Huron, Mich. 04160075 23 5 TR 0.0023 11.099 0.16625 Flint River near Fosters, Mich. 04149000 79 5 TR -0.0005 -1.869 0.21026 Cass River near Bridgeport, Mich. 04152002 79 9 TR -0.0004 -2.011 0.18427 Shiawassee River near Fergus, Mich. 04145000 75 19 TR <0.0001 -0.488 0.75828 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 1 SK 0.0001 0.669 0.48729 Saginaw River at Weadock Road at Essexville, Mich. 04157065 156 0 SK -0.0007 -2.432 0.10630 Au Sable River near Au Sable, Mich. 04137500 161 72 None NA NA NA31 Thunder Bay at Alpena, Mich. 04135020 73 43 None NA NA NA32 Black River near Port Huron, Mich. 04160055 47 10 TR 0.0022 8.930 0.051
52 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued [USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus] Watershed number Station name USGS station number Number of samples collected Number of censored results Minimum concentration Median concentration Maximum concentration Years of data used Seasons used Orthophosphate (mg/L as P)

1 Ontonagon River at Ontonagon, Mich. 04040018 70 15 0.001 0.013 0.38 14 NA2 Menominee River at Menominee, Mich. 04067648 87 29 0.001 0.006 0.016 14 NA3 Escanaba River at Wells, Mich. 040590345 82 29 0.002 0.009 0.15 15 NA4 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 79 29 0.001 0.004 0.05 14 NA5 Manistique River Above Manistique, Mich. 04057004 91 38 0.001 0.003 0.017 15 NA6 Tahquamenon River at Emerson, Mich. 04045510 84 39 0.001 0.004 0.02 15 NA7 Pine River near Charles, Mich. 04127925 71 13 0.005 0.018 0.071 14 NA8 Cheboygan River at Cheboygan, Mich. 04132052 73 28 0.001 0.002 0.013 14 NA9 Boardman River near Traverse City, Mich. 04127200 74 24 0.001 0.002 0.012 13 NA

10 Manistee River at Parkdale, Mich. 04126010 69 40 0.001 0.005 0.013 14 NA

11 Pere Marquette River at Scottville, Mich. 04122500 89 23 0.004 0.01 0.048 15 NA

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 165 70 0.001 0.008 0.042 15 NA13 Muskegon River near Hersey, Mich. (upper) 04121621 77 22 0.001 0.007 0.022 14 NA14 Grand River near Eastmanville, Mich. (lower) 04119400 167 18 0.001 0.028 0.11 15 NA15 Grand River at Ionia, Mich. (upper) 04116000 77 3 0.006 0.04 0.129 14 316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 168 31 0.001 0.012 0.118 15 NA17 Kalamazoo River near Augusta, Mich. (upper) 04105707 77 12 0.006 0.015 0.087 14 NA18 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 89 16 0.002 0.013 0.106 15 NA19 St. Joseph River at Mottville, Mich. (upper) 04099000 72 38 0.002 0.005 0.169 14 NA20 River Raisin at Monroe, Mich. 04176540 76 11 0.005 0.0195 0.13 14 NA21 Huron River at Rockwood, Mich. 04175120 71 21 0.002 0.01 0.03 14 NA22 River Rouge at River Rouge, Mich. 04168550 72 1 0.003 0.029 0.09 14 323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 162 0 0.015 0.069 0.28 14 1224 Black River at Port Huron, Mich. 04160075 23 5 0.005 0.01 0.044 6 NA25 Flint River near Fosters, Mich. 04149000 76 2 0.01 0.0495 0.16 14 326 Cass River near Bridgeport, Mich. 04152002 76 13 0.002 0.014 0.089 14 NA27 Shiawassee River near Fergus, Mich. 04145000 72 11 0.001 0.019 0.077 14 NA28 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 71 8 0.006 0.016 0.047 14 NA29 Saginaw River at Weadock Road at Essexville, Mich. 04157065 148 3 0.008 0.031 0.07 13 630 Au Sable River near Au Sable, Mich. 04137500 155 67 0.001 0.003 0.025 14 NA31 Thunder Bay at Alpena, Mich. 04135020 72 35 0.001 0.004 0.013 14 NA32 Black River near Port Huron, Mich. 04160055 47 12 0.002 0.01 0.13 8 NA
Appendix 1 53

Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued[USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus]

Watershed 

number Station name

USGS 

station 

number

Number of 

samples 

collected

Number of 

censored 

results

Trend 

test 

used

Trend in 

constituent 

units per 

year

Trend as a 

percent per 

year

p-value of 

trend

Orthophosphate (mg/L as P)—Continued

1 Ontonagon River at Ontonagon, Mich. 04040018 70 15 TR 0.0028 9.190 0.0012 Menominee River at Menominee, Mich. 04067648 87 29 None NA NA NA3 Escanaba River at Wells, Mich. 040590345 82 29 TR -0.0011 -6.478 0.0014 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 79 29 None NA NA NA5 Manistique River Above Manistique, Mich. 04057004 91 38 None NA NA NA6 Tahquamenon River at Emerson, Mich. 04045510 84 39 None NA NA NA7 Pine River near Charles, Mich. 04127925 71 13 TR 0.0003 1.253 0.5258 Cheboygan River at Cheboygan, Mich. 04132052 73 28 None NA NA NA9 Boardman River near Traverse City, Mich. 04127200 74 24 None NA NA NA

10 Manistee River at Parkdale, Mich. 04126010 69 40 None NA NA NA

11 Pere Marquette River at Scottville, Mich. 04122500 89 23 TR <0.0001 0.622 0.510

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 165 70 None NA NA NA13 Muskegon River near Hersey, Mich. (upper) 04121621 77 22 None NA NA NA14 Grand River near Eastmanville, Mich. (lower) 04119400 167 18 TR 0.0010 3.155 0.01515 Grand River at Ionia, Mich. (upper) 04116000 77 3 SK 0.0014 3.812 0.16716 Kalamazoo River at New Richmond, Mich. (lower) 04108660 168 31 TR -0.0002 -1.160 0.34517 Kalamazoo River near Augusta, Mich. (upper) 04105707 77 12 TR -0.0006 -3.415 0.02118 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 89 16 TR 0.0001 0.686 0.66119 St. Joseph River at Mottville, Mich. (upper) 04099000 72 38 None NA NA NA20 River Raisin at Monroe, Mich. 04176540 76 11 TR -0.0005 -1.524 0.37521 Huron River at Rockwood, Mich. 04175120 71 21 None NA NA NA22 River Rouge at River Rouge, Mich. 04168550 72 1 SK 0.0011 4.928 0.10323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 162 0 SK -0.0006 -0.807 0.26824 Black River at Port Huron, Mich. 04160075 23 5 TR -0.0012 -7.458 0.18125 Flint River near Fosters, Mich. 04149000 76 2 SK -0.0010 -2.558 0.20626 Cass River near Bridgeport, Mich. 04152002 76 13 TR <0.0001 0.149 0.94227 Shiawassee River near Fergus, Mich. 04145000 72 11 TR 0.0002 0.913 0.60828 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 71 8 TR -0.0002 -1.264 0.36729 Saginaw River at Weadock Road at Essexville, Mich. 04157065 148 3 SK -0.0006 -2.270 0.43030 Au Sable River near Au Sable, Mich. 04137500 155 67 None NA NA NA31 Thunder Bay at Alpena, Mich. 04135020 72 35 None NA NA NA32 Black River near Port Huron, Mich. 04160055 47 12 TR 0.0036 21.100 0.000
54 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued [USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus] Watershed number Station name USGS station number Number of samples collected Number of censored results Minimum concentration Median concentration Maximum concentration Years of data used Seasons used Phosphorus (mg/L as P)

1 Ontonagon River at Ontonagon, Mich. 04040018 70 0 0.015 0.04 1.3 14 22 Menominee River at Menominee, Mich. 04067648 87 0 0.009 0.028 0.1 14 33 Escanaba River at Wells, Mich. 040590345 91 0 0.006 0.037 0.19 15 34 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 79 2 0.004 0.019 0.048 14 65 Manistique River Above Manistique, Mich. 04057004 92 1 0.005 0.0175 0.043 15 36 Tahquamenon River at Emerson, Mich. 04045510 84 0 0.006 0.022 0.042 15 37 Pine River near Charles, Mich. 04127925 71 0 0.026 0.061 0.39 14 38 Cheboygan River at Cheboygan, Mich. 04132052 74 31 0.003 0.007 0.04 14 NA9 Boardman River near Traverse City, Mich. 04127200 76 18 0.005 0.0105 0.098 13 NA

10 Manistee River at Parkdale, Mich. 04126010 71 0 0.012 0.02 0.066 14 3

11 Pere Marquette River at Scottville, Mich. 04122500 91 0 0.011 0.033 0.14 15 3

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 173 0 0.006 0.027 0.33 15 1213 Muskegon River near Hersey, Mich. (upper) 04121621 80 0 0.013 0.03 0.183 14 414 Grand River near Eastmanville, Mich. (lower) 04119400 175 0 0.033 0.107 0.31 15 1215 Grand River at Ionia, Mich. (upper) 04116000 80 3 0.01 0.109 0.29 14 316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 175 0 0.024 0.078 0.38 15 1217 Kalamazoo River near Augusta, Mich. (upper) 04105707 79 0 0.023 0.058 0.173 14 418 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 91 0 0.027 0.065 0.4 15 319 St. Joseph River at Mottville, Mich. (upper) 04099000 74 0 0.012 0.033 0.093 14 320 River Raisin at Monroe, Mich. 04176540 79 0 0.03 0.067 0.49 14 421 Huron River at Rockwood, Mich. 04175120 79 0 0.018 0.05 0.09 14 422 River Rouge at River Rouge, Mich. 04168550 74 2 0.01 0.0755 0.22 14 323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 162 0 0.05 0.144 0.54 14 1224 Black River at Port Huron, Mich. 04160075 23 0 0.015 0.037 0.14 6 325 Flint River near Fosters, Mich. 04149000 79 0 0.049 0.134 0.73 14 326 Cass River near Bridgeport, Mich. 04152002 79 0 0.03 0.077 0.26 14 627 Shiawassee River near Fergus, Mich. 04145000 75 0 0.017 0.058 0.32 14 328 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 0 0.026 0.057 0.177 14 429 Saginaw River at Weadock Road at Essexville, Mich. 04157065 156 0 0.051 0.1 0.45 13 630 Au Sable River near Au Sable, Mich. 04137500 162 33 0.001 0.01 0.04 14 NA31 Thunder Bay at Alpena, Mich. 04135020 74 0 0.006 0.016 0.03 14 332 Black River near Port Huron, Mich. 04160055 48 0 0.024 0.059 0.65 8 4
Appendix 1 55

Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued[USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus]

Watershed 

number Station name

USGS 

station 

number

Number of 

samples 

collected

Number of 

censored 

results

Trend 

test 

used

Trend in 

constituent 

units per 

year

Trend as a 

percent per 

year

p-value of 

trend

Phosphorus (mg/L as P)—Continued

1 Ontonagon River at Ontonagon, Mich. 04040018 70 0 SK 0.0015 2.781 0.1342 Menominee River at Menominee, Mich. 04067648 87 0 SK -0.0003 -1.117 0.4243 Escanaba River at Wells, Mich. 040590345 91 0 SK 0.0003 0.749 0.8524 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 79 2 SK <0.0001 -0.515 0.6375 Manistique River Above Manistique, Mich. 04057004 92 1 SK <0.0001 -0.460 0.7206 Tahquamenon River at Emerson, Mich. 04045510 84 0 SK <0.0001 -0.319 0.4887 Pine River near Charles, Mich. 04127925 71 0 SK -0.0021 -3.377 0.0198 Cheboygan River at Cheboygan, Mich. 04132052 74 31 TR -0.0003 -3.236 0.0639 Boardman River near Traverse City, Mich. 04127200 76 18 TR -0.0002 -1.354 0.357

10 Manistee River at Parkdale, Mich. 04126010 71 0 SK -0.0001 -0.593 0.568

11 Pere Marquette River at Scottville, Mich. 04122500 91 0 SK -0.0008 -2.395 0.182

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 173 0 SK <0.0001 0.022 0.97113 Muskegon River near Hersey, Mich. (upper) 04121621 80 0 SK -0.0010 -3.456 0.21114 Grand River near Eastmanville, Mich. (lower) 04119400 175 0 SK -0.0013 -1.287 0.12115 Grand River at Ionia, Mich. (upper) 04116000 80 3 SK -0.0010 -1.033 0.61716 Kalamazoo River at New Richmond, Mich. (lower) 04108660 175 0 SK -0.0012 -1.589 0.05917 Kalamazoo River near Augusta, Mich. (upper) 04105707 79 0 SK -0.0031 -4.850 0.09818 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 91 0 SK -0.0025 -4.238 0.00819 St. Joseph River at Mottville, Mich. (upper) 04099000 74 0 SK <0.0001 0.068 0.88720 River Raisin at Monroe, Mich. 04176540 79 0 SK -0.0019 -3.076 0.03821 Huron River at Rockwood, Mich. 04175120 79 0 SK -0.0003 -0.663 0.55222 River Rouge at River Rouge, Mich. 04168550 74 2 SK 0.0011 1.590 0.11123 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 162 0 SK -0.0048 -3.369 0.01724 Black River at Port Huron, Mich. 04160075 23 0 SK <0.0001 <0.0001 1.00025 Flint River near Fosters, Mich. 04149000 79 0 SK -0.0051 -3.833 0.04726 Cass River near Bridgeport, Mich. 04152002 79 0 SK -0.0029 -4.120 0.02127 Shiawassee River near Fergus, Mich. 04145000 75 0 SK 0.0005 0.916 0.71028 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 0 SK -0.0009 -1.534 0.25729 Saginaw River at Weadock Road at Essexville, Mich. 04157065 156 0 SK -0.0019 -1.873 0.06830 Au Sable River near Au Sable, Mich. 04137500 162 33 TR <0.0001 -0.580 0.48931 Thunder Bay at Alpena, Mich. 04135020 74 0 SK -0.0004 -2.264 0.10232 Black River near Port Huron, Mich. 04160055 48 0 SK 0.0008 1.401 0.555
56 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued [USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus] Watershed number Station name USGS station number Number of samples collected Number of censored results Minimum concentration Median concentration Maximum concentration Years of data used Seasons used Total Kjeldahl nitrogen (mg/L as N)

1 Ontonagon River at Ontonagon, Mich. 04040018 70 0 0.22 0.405 2 14 22 Menominee River at Menominee, Mich. 04067648 87 0 0.27 0.48 0.97 14 33 Escanaba River at Wells, Mich. 040590345 91 0 0.41 0.63 1.06 15 34 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 79 0 0.23 0.53 1.16 14 65 Manistique River Above Manistique, Mich. 04057004 92 0 0.24 0.43 0.99 15 36 Tahquamenon River at Emerson, Mich. 04045510 84 0 0.23 0.57 1.08 15 37 Pine River near Charles, Mich. 04127925 71 0 0.24 0.55 1.25 14 38 Cheboygan River at Cheboygan, Mich. 04132052 74 0 0.19 0.275 0.84 14 39 Boardman River near Traverse City, Mich. 04127200 76 0 0.08 0.18 1.07 13 4

10 Manistee River at Parkdale, Mich. 04126010 71 0 0.16 0.23 0.8 14 3

11 Pere Marquette River at Scottville, Mich. 04122500 91 0 0.12 0.36 0.91 15 3

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 173 1 0.1 0.41 0.97 15 1213 Muskegon River near Hersey, Mich. (upper) 04121621 80 0 0.19 0.43 1.18 14 414 Grand River near Eastmanville, Mich. (lower) 04119400 175 0 0.49 1 2.7 15 1215 Grand River at Ionia, Mich. (upper) 04116000 80 3 0.1 0.93 1.58 14 316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 175 0 0.38 0.8 1.36 15 1217 Kalamazoo River near Augusta, Mich. (upper) 04105707 79 0 0.34 0.62 1.24 14 418 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 91 0 0.3 0.61 1.67 15 319 St. Joseph River at Mottville, Mich. (upper) 04099000 74 0 0.37 0.535 0.94 14 320 River Raisin at Monroe, Mich. 04176540 79 0 0.4 0.69 2.5 14 421 Huron River at Rockwood, Mich. 04175120 79 0 0.51 0.72 1.02 14 422 River Rouge at River Rouge, Mich. 04168550 74 1 0.1 0.65 4.7 14 323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 162 0 0.64 0.98 3.1 14 1224 Black River at Port Huron, Mich. 04160075 23 0 0.2 0.59 1.27 6 325 Flint River near Fosters, Mich. 04149000 79 0 0.63 0.99 4.5 14 326 Cass River near Bridgeport, Mich. 04152002 79 0 0.39 0.86 1.7 14 627 Shiawassee River near Fergus, Mich. 04145000 75 0 0.46 0.67 1.68 14 328 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 0 0.42 0.72 1.1 14 429 Saginaw River at Weadock Road at Essexville, Mich. 04157065 156 0 0.62 1.07 2.3 13 630 Au Sable River near Au Sable, Mich. 04137500 162 1 0.01 0.19 0.71 14 631 Thunder Bay at Alpena, Mich. 04135020 74 0 0.25 0.4 0.84 14 332 Black River near Port Huron, Mich. 04160055 48 0 0.31 0.77 2.5 8 4
Appendix 1 57

Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued[USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus]

Watershed 

number Station name

USGS 

station 

number

Number of 

samples 

collected

Number of 

censored 

results

Trend 

test 

used

Trend in 

constituent 

units per 

year

Trend as a 

percent per 

year

p-value of 

trend

Total Kjeldahl nitrogen (mg/L as N)—Continued

1 Ontonagon River at Ontonagon, Mich. 04040018 70 0 SK 0.0109 2.596 0.1492 Menominee River at Menominee, Mich. 04067648 87 0 SK <0.0001 0.007 1.0003 Escanaba River at Wells, Mich. 040590345 91 0 SK 0.0170 2.663 0.0184 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 79 0 SK 0.0065 1.159 0.3365 Manistique River Above Manistique, Mich. 04057004 92 0 SK 0.0042 0.875 0.7496 Tahquamenon River at Emerson, Mich. 04045510 84 0 SK <0.0001 <0.0001 1.0007 Pine River near Charles, Mich. 04127925 71 0 SK 0.0085 1.289 0.1108 Cheboygan River at Cheboygan, Mich. 04132052 74 0 SK 0.0005 0.163 0.8409 Boardman River near Traverse City, Mich. 04127200 76 0 SK 0.0006 0.329 0.866

10 Manistee River at Parkdale, Mich. 04126010 71 0 SK -0.0018 -0.774 0.559

11 Pere Marquette River at Scottville, Mich. 04122500 91 0 SK -0.0067 -1.808 0.146

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 173 1 SK 0.0008 0.185 0.70713 Muskegon River near Hersey, Mich. (upper) 04121621 80 0 SK -0.0084 -2.080 0.08614 Grand River near Eastmanville, Mich. (lower) 04119400 175 0 SK -0.0246 -2.460 0.01115 Grand River at Ionia, Mich. (upper) 04116000 80 3 SK -0.0195 -2.089 0.05416 Kalamazoo River at New Richmond, Mich. (lower) 04108660 175 0 SK -0.0128 -1.599 0.02017 Kalamazoo River near Augusta, Mich. (upper) 04105707 79 0 SK -0.0094 -1.476 0.27818 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 91 0 SK -0.0115 -1.957 0.09619 St. Joseph River at Mottville, Mich. (upper) 04099000 74 0 SK -0.0032 -0.610 0.48220 River Raisin at Monroe, Mich. 04176540 79 0 SK -0.0100 -1.522 0.14121 Huron River at Rockwood, Mich. 04175120 79 0 SK -0.0019 -0.260 0.80022 River Rouge at River Rouge, Mich. 04168550 74 1 SK 0.0231 3.608 0.04823 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 162 0 SK -0.0154 -1.575 0.02824 Black River at Port Huron, Mich. 04160075 23 0 SK <0.0001 <0.0001 1.00025 Flint River near Fosters, Mich. 04149000 79 0 SK -0.0085 -0.890 0.32326 Cass River near Bridgeport, Mich. 04152002 79 0 SK -0.0143 -1.737 0.10327 Shiawassee River near Fergus, Mich. 04145000 75 0 SK 0.0037 0.556 0.48028 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 0 SK 0.0007 0.096 1.00029 Saginaw River at Weadock Road at Essexville, Mich. 04157065 156 0 SK 0.0022 0.204 0.86230 Au Sable River near Au Sable, Mich. 04137500 162 1 SK 0.0002 0.126 0.78331 Thunder Bay at Alpena, Mich. 04135020 74 0 SK -0.0016 -0.403 0.88132 Black River near Port Huron, Mich. 04160055 48 0 SK 0.0445 5.298 0.039
58 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued [USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus] Watershed number Station name USGS station number Number of samples collected Number of censored results Minimum concentration Median concentration Maximum concentration Years of data used Seasons used Total suspended solids (mg/L)

1 Ontonagon River at Ontonagon, Mich. 04040018 70 3 4 13.5 1700 14 22 Menominee River at Menominee, Mich. 04067648 87 26 2 4 42 14 NA3 Escanaba River at Wells, Mich. 040590345 91 40 2 4 19 15 NA4 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 79 35 1 4 58 14 NA5 Manistique River Above Manistique, Mich. 04057004 92 33 4 5 41 15 NA6 Tahquamenon River at Emerson, Mich. 04045510 84 46 1 3 29 15 NA7 Pine River near Charles, Mich. 04127925 71 0 4 21 460 14 38 Cheboygan River at Cheboygan, Mich. 04132052 73 54 1 2 7 14 NA9 Boardman River near Traverse City, Mich. 04127200 76 28 2 4 75 13 NA

10 Manistee River at Parkdale, Mich. 04126010 71 10 2 8 51 14 NA

11 Pere Marquette River at Scottville, Mich. 04122500 91 13 4 12 75 15 NA

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 173 29 1 8 390 15 NA13 Muskegon River near Hersey, Mich. (upper) 04121621 80 10 2 10 140 14 NA14 Grand River near Eastmanville, Mich. (lower) 04119400 175 5 4 24 150 15 1215 Grand River at Ionia, Mich. (upper) 04116000 80 8 4 15 830 14 NA16 Kalamazoo River at New Richmond, Mich. (lower) 04108660 175 7 4 18 270 15 1217 Kalamazoo River near Augusta, Mich. (upper) 04105707 79 5 1 12 75 14 NA18 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 91 1 2 15 97 15 319 St. Joseph River at Mottville, Mich. (upper) 04099000 74 12 2 6 24 14 NA20 River Raisin at Monroe, Mich. 04176540 79 0 4 11 290 14 421 Huron River at Rockwood, Mich. 04175120 79 0 4 14 175 14 422 River Rouge at River Rouge, Mich. 04168550 74 2 4 14 64 14 323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 162 6 4 19.5 320 14 1224 Black River at Port Huron, Mich. 04160075 23 1 4 13 38 6 325 Flint River near Fosters, Mich. 04149000 79 2 4 25 300 14 326 Cass River near Bridgeport, Mich. 04152002 79 0 5 21 120 14 627 Shiawassee River near Fergus, Mich. 04145000 75 6 2 17 100 14 NA28 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 6 4 13 91 14 NA29 Saginaw River at Weadock Road at Essexville, Mich. 04157065 156 0 6 18 340 13 630 Au Sable River near Au Sable, Mich. 04137500 161 137 1 2 20 NA NA31 Thunder Bay at Alpena, Mich. 04135020 73 55 4 4 10 14 NA32 Black River near Port Huron, Mich. 04160055 48 0 4 18 410 8 4
Appendix 1 59

Appendix 1. Summary of data collected at select Michigan Water-Chemistry Monitoring Program stream sites, 1999–2013.—Continued[USGS, U.S. Geological Survey; mg/L, milligrams per liter; N, nitrogen; Mich., Michigan; NA, not available; SK, uncensored seasonal Kendall test; <, less than; TR, Tobit regression; μg/L, micrograms per liter; ng/L, nanograms per liter; P, phosphorus]

Watershed 

number Station name

USGS 

station 

number

Number of 

samples 

collected

Number of 

censored 

results

Trend 

test 

used

Trend in 

constituent 

units per 

year

Trend as a 

percent per 

year

p-value of 

trend

Total suspended solids (mg/L)—Continued

1 Ontonagon River at Ontonagon, Mich. 04040018 70 3 SK -0.2478 -1.377 0.6522 Menominee River at Menominee, Mich. 04067648 87 26 None NA NA NA3 Escanaba River at Wells, Mich. 040590345 91 40 TR 0.0598 1.139 0.3724 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 79 35 TR 0.0151 0.226 0.9045 Manistique River Above Manistique, Mich. 04057004 92 33 TR 0.0522 0.708 0.6176 Tahquamenon River at Emerson, Mich. 04045510 84 46 None NA NA NA7 Pine River near Charles, Mich. 04127925 71 0 SK -0.4447 -2.021 0.5008 Cheboygan River at Cheboygan, Mich. 04132052 73 54 None NA NA NA9 Boardman River near Traverse City, Mich. 04127200 76 28 TR 0.2438 3.381 0.108

10 Manistee River at Parkdale, Mich. 04126010 71 10 TR -0.2728 -3.041 0.065

11 Pere Marquette River at Scottville, Mich. 04122500 91 13 TR -0.2262 -1.712 0.181

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 173 29 TR -0.5078 -3.894 0.00113 Muskegon River near Hersey, Mich. (upper) 04121621 80 10 TR -0.5713 -4.077 0.03014 Grand River near Eastmanville, Mich. (lower) 04119400 175 5 SK -0.8693 -3.780 0.01815 Grand River at Ionia, Mich. (upper) 04116000 80 8 TR -1.8055 -6.756 0.00016 Kalamazoo River at New Richmond, Mich. (lower) 04108660 175 7 SK -0.2093 -1.131 0.08417 Kalamazoo River near Augusta, Mich. (upper) 04105707 79 5 TR 0.0554 0.365 0.85818 St. Joseph River at Napier Ave at St. Joseph, Mich. (lower) 04102080 91 1 SK -1.0048 -6.699 0.02019 St. Joseph River at Mottville, Mich. (upper) 04099000 74 12 TR 0.0830 1.133 0.45020 River Raisin at Monroe, Mich. 04176540 79 0 SK -0.4491 -4.491 0.05421 Huron River at Rockwood, Mich. 04175120 79 0 SK 0.0616 0.440 0.83622 River Rouge at River Rouge, Mich. 04168550 74 2 SK -0.3725 -2.865 0.25023 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 162 6 SK -0.9103 -5.689 0.02024 Black River at Port Huron, Mich. 04160075 23 1 SK 0.5077 3.905 0.72625 Flint River near Fosters, Mich. 04149000 79 2 SK -0.9900 -3.808 0.19426 Cass River near Bridgeport, Mich. 04152002 79 0 SK -1.1590 -5.795 0.02427 Shiawassee River near Fergus, Mich. 04145000 75 6 TR -0.4704 -2.294 0.15028 Tittabawassee River at Center Road near Saginaw, Mich. 04156510 79 6 TR -0.7705 -4.556 0.00329 Saginaw River at Weadock Road at Essexville, Mich. 04157065 156 0 SK -0.7918 -4.658 0.01130 Au Sable River near Au Sable, Mich. 04137500 161 137 None NA NA NA31 Thunder Bay at Alpena, Mich. 04135020 73 55 None NA NA NA32 Black River near Port Huron, Mich. 04160055 48 0 SK 0.2809 1.561 0.658
60 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year. [USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan] Water- shed number Station name USGS station number Year Drainage area, (km2

)

Annual 

mean 

discharge, 

(m3/s)

Chloride Total suspended solids

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

1 Ontonagon River at Ontonagon, Mich. 04040018 2006 3,570 31.5 17,500,000 2,450,000 4,902 17,000,000 4,080,000 4,7621 Ontonagon River at Ontonagon, Mich. 04040018 2008 3,570 29.5 2,850,000 28,500 798 367,000,000 330,300,000 102,8011 Ontonagon River at Ontonagon, Mich. 04040018 2011 3,570 24.2 17,100,000 1,881,000 4,790 15,700,000 2,355,000 4,3981 Ontonagon River at Ontonagon, Mich. 04040018 2013 3,570 45.7 7,090,000 1,276,200 1,986 386,000,000 204,580,000 108,1232 Menominee River at Menominee, Mich. 04067648 2002 10,500 121.9 23,400,000 1,872,000 2,229 58,300,000 39,644,000 5,5522 Menominee River at Menominee, Mich. 04067648 2007 10,500 63.0 14,000,000 700,000 1,333 8,580,000 4,461,600 8172 Menominee River at Menominee, Mich. 04067648 2011 10,500 82.3 18,900,000 1,890,000 1,800 30,700,000 15,964,000 2,9242 Menominee River at Menominee, Mich. 04067648 2012 10,500 56.9 15,300,000 1,530,000 1,457 11,400,000 4,560,000 1,0863 Escanaba River at Wells, Mich. 040590345 2005 2,400 17.1 9,540,000 1,621,800 3,975 3,270,000 2,681,400 1,3633 Escanaba River at Wells, Mich. 040590345 2010 2,400 15.1 10,500,000 2,415,000 4,375 3,740,000 1,383,800 1,5584 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 2006 567 4.9 351,000 35,100 619 825,000 363,000 1,4554 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 2011 567 4.8 440,000 35,200 776 2,680,000 1,849,200 4,7275 Manistique River Above Manistique, Mich. 04057004 2004 3,740 67.2 4,850,000 145,500 1,297 16,700,000 5,511,000 4,4655 Manistique River Above Manistique, Mich. 04057004 2009 3,740 42.0 3,320,000 298,800 888 8,850,000 2,301,000 2,3665 Manistique River Above Manistique, Mich. 04057004 2011 3,740 50.6 4,670,000 233,500 1,249 30,600,000 22,338,000 8,1826 Tahquamenon River at Emerson, Mich. 04045510 2004 2,090 29.8 2,170,000 65,100 1,038 4,690,000 2,251,200 2,2446 Tahquamenon River at Emerson, Mich. 04045510 2009 2,090 25.3 2,100,000 63,000 1,005 5,460,000 1,583,400 2,6127 Pine River near Charles, Mich. 04127925 2004 715 8.3 922,000 101,420 1,290 29,800,000 3,874,000 41,6787 Pine River near Charles, Mich. 04127925 2009 715 6.9 934,000 429,640 1,306 26,800,000 12,864,000 37,4838 Cheboygan River at Cheboygan, Mich. 04132052 2005 3,890 34.5 8,630,000 604,100 2,219 2,950,000 1,121,000 7588 Cheboygan River at Cheboygan, Mich. 04132052 2010 3,890 32.8 8,960,000 268,800 2,303 1,730,000 484,400 4459 Boardman River near Traverse City, Mich. 04127200 2003 699 5.5 1,460,000 87,600 2,089 751,000 277,870 1,0749 Boardman River near Traverse City, Mich. 04127200 2008 699 6.1 1,590,000 63,600 2,275 2,450,000 2,891,000 3,5059 Boardman River near Traverse City, Mich. 04127200 2013 699 7.7 2,150,000 64,500 3,076 2,550,000 688,500 3,648

10 Manistee River at Parkdale, Mich. 04126010 2004 4,480 62.7 21,300,000 2,130,000 4,754 18,700,000 1,870,000 4,17410 Manistee River at Parkdale, Mich. 04126010 2009 4,480 67.4 25,400,000 2,032,000 5,670 19,300,000 5,597,000 4,308

11 Pere Marquette River at Scottville, Mich. 04122500 2005 1,760 20.7 10,800,000 5,724,000 6,136 4,830,000 1,545,600 2,74411 Pere Marquette River at Scottville, Mich. 04122500 2010 1,760 18.1 6,530,000 718,300 3,710 6,250,000 687,500 3,551
Appendix 2 61

Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued[USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan]

Watershed 

number

Station name

USGS 

station 

number

Year

Drainage 

area, 

(km2)

Annual 

mean 

discharge, 

(m3/s)

Chloride Total suspended solids

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2)

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2)

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 2002 6,420 56.1 31,300,000 1,252,000 4,875 14,200,000 2,130,000 2,21212 Muskegon River near Bridgeton, Mich. (lower) 04122030 2003 6,420 44.8 28,200,000 846,000 4,393 33,500,000 20,435,000 5,21812 Muskegon River near Bridgeton, Mich. (lower) 04122030 2004 6,420 73.2 35,200,000 1,760,000 5,483 36,300,000 10,527,000 5,65412 Muskegon River near Bridgeton, Mich. (lower) 04122030 2005 6,420 57.6 31,600,000 1,896,000 4,922 6,820,000 3,887,400 1,06212 Muskegon River near Bridgeton, Mich. (lower) 04122030 2006 6,420 76.5 38,300,000 5,362,000 5,966 197,000,000 293,530,000 30,68512 Muskegon River near Bridgeton, Mich. (lower) 04122030 2007 6,420 59.6 33,300,000 3,330,000 5,187 16,400,000 2,296,000 2,55512 Muskegon River near Bridgeton, Mich. (lower) 04122030 2008 6,420 63.7 36,800,000 1,104,000 5,732 19,500,000 9,945,000 3,03712 Muskegon River near Bridgeton, Mich. (lower) 04122030 2009 6,420 72.2 36,700,000 1,835,000 5,717 22,100,000 9,503,000 3,44212 Muskegon River near Bridgeton, Mich. (lower) 04122030 2010 6,420 51.2 30,000,000 900,000 4,673 13,100,000 2,358,000 2,04012 Muskegon River near Bridgeton, Mich. (lower) 04122030 2011 6,420 65.1 39,000,000 1,950,000 6,075 26,800,000 6,164,000 4,17412 Muskegon River near Bridgeton, Mich. (lower) 04122030 2012 6,420 57.4 29,600,000 888,000 4,611 11,300,000 3,955,000 1,76012 Muskegon River near Bridgeton, Mich. (lower) 04122030 2013 6,420 73.5 36,800,000 4,416,000 5,732 30,700,000 5,833,000 4,78213 Muskegon River near Hersey, Mich. (upper) 04121621 2006 4,250 44.7 17,500,000 2,450,000 4,118 17,000,000 4,080,000 4,00013 Muskegon River near Hersey, Mich. (upper) 04121621 2011 4,250 35.7 17,100,000 1,881,000 4,024 15,700,000 2,355,000 3,69414 Grand River near Eastmanville, Mich. (lower) 04119400 2002 13,700 105.7 161,000,000 6,440,000 11,752 92,000,000 17,480,000 6,71514 Grand River near Eastmanville, Mich. (lower) 04119400 2003 13,700 73.8 130,000,000 18,200,000 9,489 101,000,000 35,350,000 7,37214 Grand River near Eastmanville, Mich. (lower) 04119400 2004 13,700 135.7 191,000,000 24,830,000 13,942 157,000,000 86,350,000 11,46014 Grand River near Eastmanville, Mich. (lower) 04119400 2005 13,700 104.7 169,000,000 6,760,000 12,336 59,900,000 22,163,000 4,37214 Grand River near Eastmanville, Mich. (lower) 04119400 2006 13,700 144.2 204,000,000 18,360,000 14,891 236,000,000 181,720,000 17,22614 Grand River near Eastmanville, Mich. (lower) 04119400 2007 13,700 122.9 178,000,000 7,120,000 12,993 61,100,000 23,829,000 4,46014 Grand River near Eastmanville, Mich. (lower) 04119400 2008 13,700 163.0 208,000,000 20,800,000 15,182 105,000,000 30,450,000 7,66414 Grand River near Eastmanville, Mich. (lower) 04119400 2009 13,700 186.2 202,000,000 26,260,000 14,745 136,000,000 29,920,000 9,92714 Grand River near Eastmanville, Mich. (lower) 04119400 2010 13,700 117.6 185,000,000 27,750,000 13,504 131,000,000 51,090,000 9,56214 Grand River near Eastmanville, Mich. (lower) 04119400 2011 13,700 170.7 225,000,000 24,750,000 16,423 131,000,000 52,400,000 9,56214 Grand River near Eastmanville, Mich. (lower) 04119400 2012 13,700 105.8 160,000,000 16,000,000 11,679 87,500,000 54,250,000 6,38714 Grand River near Eastmanville, Mich. (lower) 04119400 2013 13,700 154.7 202,000,000 46,460,000 14,745 133,000,000 58,520,000 9,708
62 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued [USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan] Water- shed number Station name USGS station number Year Drainage area, (km2

)

Annual 

mean 

discharge, 

(m3/s)

Chloride Total suspended solids

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

15 Grand River at Ionia, Mich. (upper) 04116000 2006 7,360 75.0 96,600,000 15,456,000 13,125 49,600,000 22,320,000 6,73915 Grand River at Ionia, Mich. (upper) 04116000 2011 7,360 90.6 122,000,000 24,400,000 16,576 68,700,000 9,618,000 9,33416 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2002 5,050 34.5 61,600,000 6,160,000 12,198 22,500,000 6,075,000 4,45516 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2003 5,050 43.3 62,200,000 4,354,000 12,317 33,000,000 5,940,000 6,53516 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2004 5,050 59.9 73,800,000 8,118,000 14,614 31,000,000 8,680,000 6,13916 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2005 5,050 55.8 71,500,000 4,290,000 14,158 29,000,000 13,630,000 5,74316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2006 5,050 62.0 77,000,000 6,160,000 15,248 31,600,000 9,164,000 6,25716 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2007 5,050 60.2 70,900,000 3,545,000 14,040 33,800,000 9,126,000 6,69316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2008 5,050 85.7 93,600,000 9,360,000 18,535 37,100,000 6,307,000 7,34716 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2009 5,050 88.7 87,900,000 11,427,000 17,406 33,000,000 7,590,000 6,53516 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2010 5,050 69.8 80,600,000 7,254,000 15,960 80,900,000 111,642,000 16,02016 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2011 5,050 73.4 82,700,000 7,443,000 16,376 49,100,000 16,694,000 9,72316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2012 5,050 50.3 61,500,000 3,075,000 12,178 23,800,000 9,044,000 4,71316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2013 5,050 63.4 79,000,000 6,320,000 15,644 35,800,000 5,012,000 7,08917 Kalamazoo River near Augusta, Mich. (upper) 04105707 2004 2,230 21.9 23,600,000 3,776,000 10,583 9,980,000 4,690,600 4,47517 Kalamazoo River near Augusta, Mich. (upper) 04105707 2009 2,230 31.3 29,500,000 2,655,000 13,229 8,600,000 1,634,000 3,85717 Kalamazoo River near Augusta, Mich. (upper) 04105707 2011 2,230 27.8 27,200,000 3,536,000 12,197 18,200,000 3,640,000 8,16118

St. Joseph River at Napier Ave at St. Joseph, Mich. 

(lower) 04102080 2005 11,000 107.1 88,800,000 7,104,000 8,073 25,800,000 5,418,000 2,345

18

St. Joseph River at Napier Ave at St. Joseph, Mich. 

(lower) 04102080 2011 11,000 139.5 126,000,000 5,040,000 11,455 115,000,000 37,950,000 10,455

19 St. Joseph River at Mottville, Mich. (upper) 04099000 2006 4,830 49.9 37,700,000 2,262,000 7,805 10,300,000 4,841,000 2,13319 St. Joseph River at Mottville, Mich. (upper) 04099000 2010 4,830 48.2 34,600,000 1,730,000 7,164 13,200,000 2,376,000 2,73320 River Raisin at Monroe, Mich. 04176540 2003 2,750 17.2 25,900,000 3,108,000 9,418 30,600,000 15,300,000 11,12720 River Raisin at Monroe, Mich. 04176540 2008 2,750 34.9 27,100,000 8,943,000 9,855 24,600,000 4,428,000 8,94520 River Raisin at Monroe, Mich. 04176540 2013 2,750 20.4 29,700,000 2,079,000 10,800 62,600,000 90,144,000 22,76421 Huron River at Rockwood, Mich. 04175120 2002 2,200 13.1 41,200,000 2,060,000 18,727 4,640,000 1,809,600 2,10921 Huron River at Rockwood, Mich. 04175120 2007 2,200 18.8 55,100,000 8,265,000 25,045 10,100,000 3,030,000 4,59121 Huron River at Rockwood, Mich. 04175120 2012 2,200 15.1 38,200,000 3,056,000 17,364 4,230,000 2,453,400 1,923
Appendix 2 63

Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued[USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan]

Watershed 

number

Station name

USGS 

station 

number

Year

Drainage 

area, 

(km2)

Annual 

mean 

discharge, 

(m3/s)

Chloride Total suspended solids

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2)

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2)

22 River Rouge at River Rouge, Mich. 04168550 2005 1,200 11.6 23,900,000 4,780,000 19,917 4,790,000 1,101,700 3,99222 River Rouge at River Rouge, Mich. 04168550 2010 1,200 10.7 53,500,000 1,605,000 44,583 10,100,000 2,525,000 8,41723 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2002 1,900 13.1 57,300,000 4,584,000 30,158 24,400,000 12,200,000 12,84223 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2003 1,900 13.1 76,700,000 12,272,000 40,368 44,300,000 25,251,000 23,31623 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2004 1,900 19.2 80,300,000 21,681,000 42,263 59,500,000 23,205,000 31,31623 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2005 1,900 16.3 72,900,000 26,244,000 38,368 10,800,000 3,996,000 5,68423 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2006 1,900 22.6 74,200,000 10,388,000 39,053 32,700,000 3,597,000 17,21123 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2007 1,900 16.7 81,100,000 12,976,000 42,684 18,300,000 11,163,000 9,63223 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2008 1,900 23.1 93,900,000 28,170,000 49,421 17,200,000 6,020,000 9,05323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2009 1,900 31.6 99,100,000 20,811,000 52,158 41,500,000 14,940,000 21,84223 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2010 1,900 14.8 76,700,000 9,971,000 40,368 11,600,000 3,828,000 6,10523 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2011 1,900 29.4 125,000,000 15,000,000 65,789 65,600,000 29,520,000 34,52623 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2012 1,900 12.9 52,000,000 9,880,000 27,368 3,400,000 1,394,000 1,78923 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2013 1,900 19.6 74,800,000 10,472,000 39,368 24,600,000 7,134,000 12,94725 Flint River near Fosters, Mich. 04149000 2003 2,990 15.2 49,400,000 16,302,000 16,522 36,000,000 33,120,000 12,04025 Flint River near Fosters, Mich. 04149000 2008 2,990 29.2 53,400,000 4,272,000 17,860 27,900,000 6,696,000 9,33125 Flint River near Fosters, Mich. 04149000 2013 2,990 31.9 57,200,000 6,864,000 19,130 107,000,000 79,180,000 35,78626 Cass River near Bridgeport, Mich. 04152002 2006 2,350 26.5 18,600,000 7,812,000 7,915 45,600,000 47,880,000 19,40426 Cass River near Bridgeport, Mich. 04152002 2011 2,350 24.3 25,000,000 2,000,000 10,638 32,200,000 9,338,000 13,70227 Shiawassee River near Fergus, Mich. 04145000 2005 1,650 13.4 15,400,000 2,156,000 9,333 3,140,000 1,067,600 1,90327 Shiawassee River near Fergus, Mich. 04145000 2010 1,650 10.3 22,100,000 4,199,000 13,394 8,540,000 2,562,000 5,17628

Tittabawassee River at Center Road near Saginaw, 

Mich. 04156510 2002 6,550 51.1 89,700,000 19,734,000 13,695 36,000,000 25,560,000 5,496

28

Tittabawassee River at Center Road near Saginaw, 

Mich. 04156510 2007 6,550 54.9 98,800,000 16,796,000 15,084 42,200,000 17,302,000 6,443

28

Tittabawassee River at Center Road near Saginaw, 

Mich. 04156510 2012 6,550 46.5 110,000,000 20,900,000 16,794 19,500,000 5,070,000 2,977
64 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued [USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan] Water- shed number Station name USGS station number Year Drainage area, (km2

)

Annual 

mean 

discharge, 

(m3/s)

Chloride Total suspended solids

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

29 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2002 16,100 124.3 252,000,000 57,960,000 15,652 181,000,000 240,730,000 11,24229 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2003 16,100 69.8 209,000,000 45,980,000 12,981 47,400,000 9,480,000 2,94429 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2004 16,100 152.3 261,000,000 46,980,000 16,211 350,000,000 140,000,000 21,73929 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2005 16,100 121.5 224,000,000 58,240,000 13,913 56,900,000 18,777,000 3,53429 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2006 16,100 184.4 257,000,000 74,530,000 15,963 431,000,000 383,590,000 26,77029 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2007 16,100 125.5 236,000,000 23,600,000 14,658 92,000,000 42,320,000 5,71429 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2008 16,100 146.2 253,000,000 17,710,000 15,714 184,000,000 93,840,000 11,42929 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2009 16,100 192.2 243,000,000 51,030,000 15,093 216,000,000 153,360,000 13,41629 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2010 16,100 99.6 218,000,000 45,780,000 13,540 88,100,000 52,860,000 5,47229 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2011 16,100 170.3 297,000,000 53,460,000 18,447 216,000,000 56,160,000 13,41629 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2012 16,100 103.8 193,000,000 23,160,000 11,988 40,900,000 9,816,000 2,54029 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2013 16,100 182.8 242,000,000 58,080,000 15,031 288,000,000 567,360,000 17,88830 Au Sable River near Au Sable, Mich. 04137500 2002 4,500 34.6 6,810,000 612,900 1,513 29,800 14,006 730 Au Sable River near Au Sable, Mich. 04137500 2003 4,500 32.1 6,230,000 62,300 1,384 2,080,000 20,800 46230 Au Sable River near Au Sable, Mich. 04137500 2004 4,500 39.0 10,500,000 4,935,000 2,333 2,540,000 0 56430 Au Sable River near Au Sable, Mich. 04137500 2005 4,500 36.7 6,950,000 278,000 1,544 494,000 429,780 11030 Au Sable River near Au Sable, Mich. 04137500 2006 4,500 42.4 8,540,000 597,800 1,898 2,850,000 1,311,000 63330 Au Sable River near Au Sable, Mich. 04137500 2007 4,500 36.9 7,350,000 367,500 1,633 1,540,000 708,400 34230 Au Sable River near Au Sable, Mich. 04137500 2008 4,500 40.7 8,130,000 487,800 1,807 1,320,000 567,600 29330 Au Sable River near Au Sable, Mich. 04137500 2009 4,500 40.4 7,900,000 79,000 1,756 5,280,000 316,800 1,17330 Au Sable River near Au Sable, Mich. 04137500 2010 4,500 34.2 7,140,000 357,000 1,587 1,490,000 506,600 33130 Au Sable River near Au Sable, Mich. 04137500 2011 4,500 36.9 7,560,000 226,800 1,680 5,240,000 471,600 1,16430 Au Sable River near Au Sable, Mich. 04137500 2012 4,500 34.4 6,560,000 590,400 1,458 2,440,000 488,000 54230 Au Sable River near Au Sable, Mich. 04137500 2013 4,500 39.1 7,770,000 543,900 1,727 3,590,000 753,900 79831 Thunder Bay at Alpena, Mich. 04135020 2005 3,210 21.0 4,140,000 496,800 1,290 2,060,000 453,200 64231 Thunder Bay at Alpena, Mich. 04135020 2010 3,210 19.0 4,420,000 176,800 1,377 1,430,000 371,800 44532 Black River near Port Huron, Mich. 04160055 2007 1,770 9.5 7,310,000 5,043,900 4,130 39,500,000 11,455,000 22,31632 Black River near Port Huron, Mich. 04160055 2012 1,770 6.8 7,130,000 1,568,600 4,028 2,890,000 664,700 1,633
Appendix 2 65

Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued[USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan]

Watershed 

number

Station name

USGS 

station 

number

Year

Drainage 

area, 

(km2)

Annual 

mean 

discharge, 

(m3/s)

Total phosphorus Copper

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2)

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2)

1 Ontonagon River at Ontonagon, Mich. 04040018 2006 3,570 31.5 64,200 7,062 17.98 1,340 80 0.381 Ontonagon River at Ontonagon, Mich. 04040018 2008 3,570 29.5 277,000 199,440 77.59 18,300 15,555 5.131 Ontonagon River at Ontonagon, Mich. 04040018 2011 3,570 24.2 47,100 10,833 13.19 1,130 181 0.321 Ontonagon River at Ontonagon, Mich. 04040018 2013 3,570 45.7 370,000 196,100 103.64 14,500 7,250 4.062 Menominee River at Menominee, Mich. 04067648 2002 10,500 121.9 209,000 71,060 19.90 4,750 570 0.452 Menominee River at Menominee, Mich. 04067648 2007 10,500 63.0 56,200 9,554 5.35 1,670 267 0.162 Menominee River at Menominee, Mich. 04067648 2011 10,500 82.3 96,200 25,012 9.16 2,530 380 0.242 Menominee River at Menominee, Mich. 04067648 2012 10,500 56.9 45,800 5,954 4.36 1,360 68 0.133 Escanaba River at Wells, Mich. 040590345 2005 2,400 17.1 20,300 4,872 8.46 528 121 0.223 Escanaba River at Wells, Mich. 040590345 2010 2,400 15.1 19,700 3,349 8.21 337 27 0.144 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 2006 567 4.9 3,590 467 6.33 120 70 0.214 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 2011 567 4.8 5,420 867 9.56 97 12 0.175 Manistique River Above Manistique, Mich. 04057004 2004 3,740 67.2 48,900 9,291 13.07 1,020 133 0.275 Manistique River Above Manistique, Mich. 04057004 2009 3,740 42.0 26,600 3,192 7.11 602 96 0.165 Manistique River Above Manistique, Mich. 04057004 2011 3,740 50.6 45,900 16,065 12.27 818 65 0.226 Tahquamenon River at Emerson, Mich. 04045510 2004 2,090 29.8 27,300 5,733 13.06 467 70 0.226 Tahquamenon River at Emerson, Mich. 04045510 2009 2,090 25.3 21,900 3,285 10.48 368 37 0.187 Pine River near Charles, Mich. 04127925 2004 715 8.3 37,300 6,714 52.17 767 123 1.077 Pine River near Charles, Mich. 04127925 2009 715 6.9 44,700 14,304 62.52 573 149 0.808 Cheboygan River at Cheboygan, Mich. 04132052 2005 3,890 34.5 12,400 4,588 3.19 665 53 0.178 Cheboygan River at Cheboygan, Mich. 04132052 2010 3,890 32.8 10,100 2,525 2.60 536 32 0.149 Boardman River near Traverse City, Mich. 04127200 2003 699 5.5 2,450 588 3.51 51 10 0.079 Boardman River near Traverse City, Mich. 04127200 2008 699 6.1 3,990 3,631 5.71 102 47 0.159 Boardman River near Traverse City, Mich. 04127200 2013 699 7.7 4,420 1,680 6.32 125 20 0.18

10 Manistee River at Parkdale, Mich. 04126010 2004 4,480 62.7 48,000 2,400 10.71 893 71 0.2010 Manistee River at Parkdale, Mich. 04126010 2009 4,480 67.4 47,200 6,608 10.54 1,000 30 0.22

11 Pere Marquette River at Scottville, Mich. 04122500 2005 1,760 20.7 18,000 3,960 10.23 314 44 0.1811 Pere Marquette River at Scottville, Mich. 04122500 2010 1,760 18.1 22,000 4,400 12.50 286 66 0.16
66 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued [USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan] Water- shed number Station name USGS station number Year Drainage area, (km2

)

Annual 

mean 

discharge, 

(m3/s)

Total phosphorus Copper

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 2002 6,420 56.1 37,400 8,228 5.83 1,050 95 0.1612 Muskegon River near Bridgeton, Mich. (lower) 04122030 2003 6,420 44.8 48,500 23,280 7.55 892 125 0.1412 Muskegon River near Bridgeton, Mich. (lower) 04122030 2004 6,420 73.2 88,000 13,200 13.71 2,010 141 0.3112 Muskegon River near Bridgeton, Mich. (lower) 04122030 2005 6,420 57.6 35,600 4,628 5.55 1,320 106 0.2112 Muskegon River near Bridgeton, Mich. (lower) 04122030 2006 6,420 76.5 208,000 230,880 32.40 4,480 4,570 0.7012 Muskegon River near Bridgeton, Mich. (lower) 04122030 2007 6,420 59.6 52,500 7,350 8.18 1,360 109 0.2112 Muskegon River near Bridgeton, Mich. (lower) 04122030 2008 6,420 63.7 63,400 13,948 9.88 1,600 144 0.2512 Muskegon River near Bridgeton, Mich. (lower) 04122030 2009 6,420 72.2 68,800 8,256 10.72 1,750 140 0.2712 Muskegon River near Bridgeton, Mich. (lower) 04122030 2010 6,420 51.2 43,800 6,132 6.82 1,010 40 0.1612 Muskegon River near Bridgeton, Mich. (lower) 04122030 2011 6,420 65.1 66,300 9,282 10.33 1,620 97 0.2512 Muskegon River near Bridgeton, Mich. (lower) 04122030 2012 6,420 57.4 47,200 9,440 7.35 1,150 46 0.1812 Muskegon River near Bridgeton, Mich. (lower) 04122030 2013 6,420 73.5 73,500 8,085 11.45 2,150 172 0.3313 Muskegon River near Hersey, Mich. (upper) 04121621 2006 4,250 44.7 64,200 7,062 15.11 1,340 80 0.3213 Muskegon River near Hersey, Mich. (upper) 04121621 2011 4,250 35.7 47,100 10,833 11.08 1,130 181 0.2714 Grand River near Eastmanville, Mich. (lower) 04119400 2002 13,700 105.7 322,000 35,420 23.50 7,930 1,031 0.5814 Grand River near Eastmanville, Mich. (lower) 04119400 2003 13,700 73.8 345,000 93,150 25.18 7,700 1,694 0.5614 Grand River near Eastmanville, Mich. (lower) 04119400 2004 13,700 135.7 658,000 92,120 48.03 13,000 1,690 0.9514 Grand River near Eastmanville, Mich. (lower) 04119400 2005 13,700 104.7 256,000 38,400 18.69 6,230 872 0.4514 Grand River near Eastmanville, Mich. (lower) 04119400 2006 13,700 144.2 683,000 252,710 49.85 14,600 3,942 1.0714 Grand River near Eastmanville, Mich. (lower) 04119400 2007 13,700 122.9 384,000 61,440 28.03 9,270 1,020 0.6814 Grand River near Eastmanville, Mich. (lower) 04119400 2008 13,700 163.0 604,000 102,680 44.09 11,800 944 0.8614 Grand River near Eastmanville, Mich. (lower) 04119400 2009 13,700 186.2 746,000 119,360 54.45 14,000 1,400 1.0214 Grand River near Eastmanville, Mich. (lower) 04119400 2010 13,700 117.6 475,000 109,250 34.67 8,860 1,418 0.6514 Grand River near Eastmanville, Mich. (lower) 04119400 2011 13,700 170.7 622,000 74,640 45.40 14,700 735 1.0714 Grand River near Eastmanville, Mich. (lower) 04119400 2012 13,700 105.8 359,000 96,930 26.20 6,610 1,454 0.4814 Grand River near Eastmanville, Mich. (lower) 04119400 2013 13,700 154.7 697,000 111,520 50.88 14,900 1,937 1.0915 Grand River at Ionia, Mich. (upper) 04116000 2006 7,360 75.0 311,000 68,420 42.26 7,060 988 0.9615 Grand River at Ionia, Mich. (upper) 04116000 2011 7,360 90.6 426,000 42,600 57.88 9,640 482 1.31
Appendix 2 67

Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued[USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan]

Watershed 

number

Station name

USGS 

station 

number

Year

Drainage 

area, 

(km2)

Annual 

mean 

discharge, 

(m3/s)

Total phosphorus Copper

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2)

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2)

16 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2002 5,050 34.5 202,000 191,900 40.00 2,120 466 0.4216 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2003 5,050 43.3 151,000 36,240 29.90 2,330 303 0.4616 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2004 5,050 59.9 162,000 22,680 32.08 3,050 305 0.6016 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2005 5,050 55.8 110,000 31,900 21.78 2,080 354 0.4116 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2006 5,050 62.0 145,000 27,550 28.71 2,840 284 0.5616 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2007 5,050 60.2 130,000 24,700 25.74 2,490 274 0.4916 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2008 5,050 85.7 228,000 79,800 45.15 4,200 714 0.8316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2009 5,050 88.7 235,000 44,650 46.53 4,310 431 0.8516 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2010 5,050 69.8 237,000 123,240 46.93 3,950 1,501 0.7816 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2011 5,050 73.4 241,000 106,040 47.72 4,090 450 0.8116 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2012 5,050 50.3 93,800 14,070 18.57 1,850 111 0.3716 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2013 5,050 63.4 156,000 17,160 30.89 3,020 242 0.6017 Kalamazoo River near Augusta, Mich. (upper) 04105707 2004 2,230 21.9 57,000 6,840 25.56 1,200 216 0.5417 Kalamazoo River near Augusta, Mich. (upper) 04105707 2009 2,230 31.3 47,400 4,740 21.26 1,080 76 0.4817 Kalamazoo River near Augusta, Mich. (upper) 04105707 2011 2,230 27.8 62,800 14,444 28.16 1,430 57 0.6418

St. Joseph River at Napier Ave at St. Joseph, Mich. 

(lower) 04102080 2005 11,000 107.1 123,000 7,380 11.18 3,730 149 0.34

18

St. Joseph River at Napier Ave at St. Joseph, Mich. 

(lower) 04102080 2011 11,000 139.5 419,000 108,940 38.09 9,160 1,466 0.83

19 St. Joseph River at Mottville, Mich. (upper) 04099000 2006 4,830 49.9 54,500 8,720 11.28 1,390 222 0.2919 St. Joseph River at Mottville, Mich. (upper) 04099000 2010 4,830 48.2 63,900 5,751 13.23 1,220 98 0.2520 River Raisin at Monroe, Mich. 04176540 2003 2,750 17.2 107,000 49,220 38.91 2,040 632 0.7420 River Raisin at Monroe, Mich. 04176540 2008 2,750 34.9 127,000 22,860 46.18 3,170 539 1.1520 River Raisin at Monroe, Mich. 04176540 2013 2,750 20.4 148,000 116,920 53.82 2,980 1,579 1.0821 Huron River at Rockwood, Mich. 04175120 2002 2,200 13.1 16,400 3,116 7.45 702 56 0.3221 Huron River at Rockwood, Mich. 04175120 2007 2,200 18.8 28,700 4,879 13.05 1,050 63 0.4821 Huron River at Rockwood, Mich. 04175120 2012 2,200 15.1 14,900 4,172 6.77 533 80 0.24
68 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued [USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan] Water- shed number Station name USGS station number Year Drainage area, (km2

)

Annual 

mean 

discharge, 

(m3/s)

Total phosphorus Copper

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

22 River Rouge at River Rouge, Mich. 04168550 2005 1,200 11.6 21,100 3,376 17.58 873 96 0.7322 River Rouge at River Rouge, Mich. 04168550 2010 1,200 10.7 46,900 5,159 39.08 1,330 173 1.1123 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2002 1,900 13.1 83,000 19,920 43.68 2,120 488 1.1223 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2003 1,900 13.1 118,000 49,560 62.11 3,800 1,786 2.0023 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2004 1,900 19.2 152,000 33,440 80.00 4,190 838 2.2123 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2005 1,900 16.3 53,500 5,350 28.16 1,670 217 0.8823 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2006 1,900 22.6 119,000 13,090 62.63 3,190 383 1.6823 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2007 1,900 16.7 73,500 21,315 38.68 1,970 374 1.0423 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2008 1,900 23.1 82,000 13,940 43.16 2,330 443 1.2323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2009 1,900 31.6 158,000 41,080 83.16 3,990 399 2.1023 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2010 1,900 14.8 65,300 4,571 34.37 1,760 194 0.9323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2011 1,900 29.4 198,000 43,560 104.21 6,890 2,136 3.6323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2012 1,900 12.9 50,200 10,040 26.42 1,380 497 0.7323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2013 1,900 19.6 94,500 7,560 49.74 3,020 362 1.5925 Flint River near Fosters, Mich. 04149000 2003 2,990 15.2 108,000 93,960 36.12 2,430 1,774 0.8125 Flint River near Fosters, Mich. 04149000 2008 2,990 29.2 114,000 18,240 38.13 2,440 293 0.8225 Flint River near Fosters, Mich. 04149000 2013 2,990 31.9 242,000 113,740 80.94 4,780 2,008 1.6026 Cass River near Bridgeport, Mich. 04152002 2006 2,350 26.5 122,000 47,580 51.91 2,190 548 0.9326 Cass River near Bridgeport, Mich. 04152002 2011 2,350 24.3 108,000 18,360 45.96 2,380 214 1.0127 Shiawassee River near Fergus, Mich. 04145000 2005 1,650 13.4 13,000 4,160 7.88 392 86 0.2427 Shiawassee River near Fergus, Mich. 04145000 2010 1,650 10.3 30,200 11,174 18.30 643 116 0.3928

Tittabawassee River at Center Road near Saginaw, 

Mich. 04156510 2002 6,550 51.1 125,000 31,250 19.08 3,150 315 0.48

28

Tittabawassee River at Center Road near Saginaw, 

Mich. 04156510 2007 6,550 54.9 119,000 10,710 18.17 4,550 1,320 0.69

28

Tittabawassee River at Center Road near Saginaw, 

Mich. 04156510 2012 6,550 46.5 82,900 7,461 12.66 2,450 196 0.37
Appendix 2 69

Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued[USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan]

Watershed 

number

Station name

USGS 

station 

number

Year

Drainage 

area, 

(km2)

Annual 

mean 

discharge, 

(m3/s)

Total phosphorus Copper

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2)

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2)

29 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2002 16,100 124.3 513,000 369,360 31.86 10,500 4,830 0.6529 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2003 16,100 69.8 227,000 22,700 14.10 5,030 503 0.3129 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2004 16,100 152.3 724,000 130,320 44.97 17,500 3,325 1.0929 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2005 16,100 121.5 288,000 28,800 17.89 6,740 1,011 0.4229 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2006 16,100 184.4 922,000 36,880 57.27 19,400 6,014 1.2029 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2007 16,100 125.5 400,000 128,000 24.84 9,050 1,720 0.5629 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2008 16,100 146.2 580,000 156,600 36.02 13,300 3,059 0.8329 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2009 16,100 192.2 806,000 290,160 50.06 15,800 3,160 0.9829 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2010 16,100 99.6 331,000 95,990 20.56 7,720 1,853 0.4829 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2011 16,100 170.3 782,000 78,200 48.57 17,600 704 1.0929 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2012 16,100 103.8 273,000 38,220 16.96 5,950 1,190 0.3729 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2013 16,100 182.8 756,000 264,600 46.96 16,600 4,316 1.0330 Au Sable River near Au Sable, Mich. 04137500 2002 4,500 34.6 8,070 1,372 1.79 232 35 0.0530 Au Sable River near Au Sable, Mich. 04137500 2003 4,500 32.1 11,100 1,998 2.47 219 39 0.0530 Au Sable River near Au Sable, Mich. 04137500 2004 4,500 39.0 12,200 2,440 2.71 386 66 0.0930 Au Sable River near Au Sable, Mich. 04137500 2005 4,500 36.7 9,990 1,698 2.22 383 46 0.0930 Au Sable River near Au Sable, Mich. 04137500 2006 4,500 42.4 13,700 2,055 3.04 416 29 0.0930 Au Sable River near Au Sable, Mich. 04137500 2007 4,500 36.9 12,500 1,625 2.78 376 41 0.0830 Au Sable River near Au Sable, Mich. 04137500 2008 4,500 40.7 13,100 1,441 2.91 475 14 0.1130 Au Sable River near Au Sable, Mich. 04137500 2009 4,500 40.4 12,200 976 2.71 324 10 0.0730 Au Sable River near Au Sable, Mich. 04137500 2010 4,500 34.2 13,300 5,187 2.96 282 6 0.0630 Au Sable River near Au Sable, Mich. 04137500 2011 4,500 36.9 12,100 968 2.69 414 99 0.0930 Au Sable River near Au Sable, Mich. 04137500 2012 4,500 34.4 8,470 2,541 1.88 261 47 0.0630 Au Sable River near Au Sable, Mich. 04137500 2013 4,500 39.1 10,400 1,456 2.31 307 28 0.0731 Thunder Bay at Alpena, Mich. 04135020 2005 3,210 21.0 11,900 3,451 3.71 310 59 0.1031 Thunder Bay at Alpena, Mich. 04135020 2010 3,210 19.0 11,200 2,128 3.49 257 23 0.0832 Black River near Port Huron, Mich. 04160055 2007 1,770 9.5 76,000 18,240 42.94 1,300 208 0.7332 Black River near Port Huron, Mich. 04160055 2012 1,770 6.8 14,200 5,822 8.02 398 131 0.22
70 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued [USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan] Water- shed number Station name USGS station number Year Drainage area, (km2

)

Annual 

mean 

discharge, 

(m3/s)

Chromium Lead

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

1 Ontonagon River at Ontonagon, Mich. 04040018 2006 3,570 31.5 706 198 0.20 460 138 0.131 Ontonagon River at Ontonagon, Mich. 04040018 2008 3,570 29.5 18,700 17,578 5.24 4,720 3,918 1.321 Ontonagon River at Ontonagon, Mich. 04040018 2011 3,570 24.2 718 72 0.20 347 59 0.101 Ontonagon River at Ontonagon, Mich. 04040018 2013 3,570 45.7 9,020 5,322 2.53 3,980 2,348 1.112 Menominee River at Menominee, Mich. 04067648 2002 10,500 121.9 1,950 624 0.19 1,410 522 0.132 Menominee River at Menominee, Mich. 04067648 2007 10,500 63.0 1,240 236 0.12 234 59 0.022 Menominee River at Menominee, Mich. 04067648 2011 10,500 82.3 1,840 405 0.18 1,260 769 0.122 Menominee River at Menominee, Mich. 04067648 2012 10,500 56.9 789 134 0.08 229 48 0.023 Escanaba River at Wells, Mich. 040590345 2005 2,400 17.1 227 66 0.09 152 88 0.063 Escanaba River at Wells, Mich. 040590345 2010 2,400 15.1 335 70 0.14 123 25 0.054 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 2006 567 4.9 78 13 0.14 30 6 0.054 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 2011 567 4.8 131 25 0.23 53 10 0.095 Manistique River Above Manistique, Mich. 04057004 2004 3,740 67.2 1,100 220 0.29 620 198 0.175 Manistique River Above Manistique, Mich. 04057004 2009 3,740 42.0 667 60 0.18 245 47 0.075 Manistique River Above Manistique, Mich. 04057004 2011 3,740 50.6 1,060 117 0.28 416 146 0.116 Tahquamenon River at Emerson, Mich. 04045510 2004 2,090 29.8 438 110 0.21 292 76 0.146 Tahquamenon River at Emerson, Mich. 04045510 2009 2,090 25.3 446 45 0.21 228 18 0.117 Pine River near Charles, Mich. 04127925 2004 715 8.3 954 200 1.33 440 88 0.627 Pine River near Charles, Mich. 04127925 2009 715 6.9 660 218 0.92 352 116 0.498 Cheboygan River at Cheboygan, Mich. 04132052 2005 3,890 34.5 39 29 0.01 52 15 0.018 Cheboygan River at Cheboygan, Mich. 04132052 2010 3,890 32.8 235 134 0.06 38 8 0.019 Boardman River near Traverse City, Mich. 04127200 2003 699 5.5 9 5 0.01 37 10 0.059 Boardman River near Traverse City, Mich. 04127200 2008 699 6.1 86 54 0.12 48 57 0.079 Boardman River near Traverse City, Mich. 04127200 2013 699 7.7 132 18 0.19 71 32 0.10

10 Manistee River at Parkdale, Mich. 04126010 2004 4,480 62.7 494 49 0.11 380 27 0.0810 Manistee River at Parkdale, Mich. 04126010 2009 4,480 67.4 1,080 140 0.24 357 29 0.08

11 Pere Marquette River at Scottville, Mich. 04122500 2005 1,760 20.7 66 20 0.04 119 23 0.0711 Pere Marquette River at Scottville, Mich. 04122500 2010 1,760 18.1 355 195 0.20 167 22 0.09
Appendix 2 71

Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued[USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan]

Watershed 

number

Station name

USGS 

station 

number

Year

Drainage 

area, 

(km2)

Annual 

mean 

discharge, 

(m3/s)

Chromium Lead

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2)

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2)

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 2002 6,420 56.1 210 113 0.03 272 112 0.0412 Muskegon River near Bridgeton, Mich. (lower) 04122030 2003 6,420 44.8 256 143 0.04 438 206 0.0712 Muskegon River near Bridgeton, Mich. (lower) 04122030 2004 6,420 73.2 690 166 0.11 675 149 0.1112 Muskegon River near Bridgeton, Mich. (lower) 04122030 2005 6,420 57.6 88 40 0.01 168 30 0.0312 Muskegon River near Bridgeton, Mich. (lower) 04122030 2006 6,420 76.5 3,920 5,253 0.61 4,190 6,285 0.6512 Muskegon River near Bridgeton, Mich. (lower) 04122030 2007 6,420 59.6 1,260 214 0.20 348 73 0.0512 Muskegon River near Bridgeton, Mich. (lower) 04122030 2008 6,420 63.7 980 196 0.15 375 135 0.0612 Muskegon River near Bridgeton, Mich. (lower) 04122030 2009 6,420 72.2 903 117 0.14 484 106 0.0812 Muskegon River near Bridgeton, Mich. (lower) 04122030 2010 6,420 51.2 440 317 0.07 232 35 0.0412 Muskegon River near Bridgeton, Mich. (lower) 04122030 2011 6,420 65.1 1,220 171 0.19 420 71 0.0712 Muskegon River near Bridgeton, Mich. (lower) 04122030 2012 6,420 57.4 599 132 0.09 296 21 0.0512 Muskegon River near Bridgeton, Mich. (lower) 04122030 2013 6,420 73.5 1,420 426 0.22 702 147 0.1113 Muskegon River near Hersey, Mich. (upper) 04121621 2006 4,250 44.7 706 198 0.17 460 138 0.1113 Muskegon River near Hersey, Mich. (upper) 04121621 2011 4,250 35.7 718 72 0.17 347 59 0.0814 Grand River near Eastmanville, Mich. (lower) 04119400 2002 13,700 105.7 3,570 1,178 0.26 4,800 1,344 0.3514 Grand River near Eastmanville, Mich. (lower) 04119400 2003 13,700 73.8 3,500 1,085 0.26 5,440 2,394 0.4014 Grand River near Eastmanville, Mich. (lower) 04119400 2004 13,700 135.7 5,710 2,113 0.42 7,680 2,765 0.5614 Grand River near Eastmanville, Mich. (lower) 04119400 2005 13,700 104.7 1,280 448 0.09 2,660 931 0.1914 Grand River near Eastmanville, Mich. (lower) 04119400 2006 13,700 144.2 8,340 4,837 0.61 10,100 6,161 0.7414 Grand River near Eastmanville, Mich. (lower) 04119400 2007 13,700 122.9 5,340 1,388 0.39 3,910 1,173 0.2914 Grand River near Eastmanville, Mich. (lower) 04119400 2008 13,700 163.0 8,900 1,958 0.65 6,210 2,236 0.4514 Grand River near Eastmanville, Mich. (lower) 04119400 2009 13,700 186.2 8,020 882 0.59 6,930 1,317 0.5114 Grand River near Eastmanville, Mich. (lower) 04119400 2010 13,700 117.6 5,480 1,754 0.40 5,060 2,075 0.3714 Grand River near Eastmanville, Mich. (lower) 04119400 2011 13,700 170.7 7,890 1,815 0.58 5,880 1,882 0.4314 Grand River near Eastmanville, Mich. (lower) 04119400 2012 13,700 105.8 3,720 1,674 0.27 3,220 1,578 0.2414 Grand River near Eastmanville, Mich. (lower) 04119400 2013 13,700 154.7 9,140 3,108 0.67 8,420 3,536 0.61
72 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued [USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan] Water- shed number Station name USGS station number Year Drainage area, (km2

)

Annual 

mean 

discharge, 

(m3/s)

Chromium Lead

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

15 Grand River at Ionia, Mich. (upper) 04116000 2006 7,360 75.0 2,780 945 0.38 3,000 1,320 0.4115 Grand River at Ionia, Mich. (upper) 04116000 2011 7,360 90.6 4,260 341 0.58 4,380 482 0.6016 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2002 5,050 34.5 839 394 0.17 1,750 438 0.3516 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2003 5,050 43.3 855 154 0.17 1,990 259 0.3916 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2004 5,050 59.9 1,070 278 0.21 2,380 333 0.4716 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2005 5,050 55.8 380 91 0.08 1,690 372 0.3316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2006 5,050 62.0 1,450 493 0.29 2,120 466 0.4216 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2007 5,050 60.2 2,150 452 0.43 2,080 603 0.4116 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2008 5,050 85.7 2,550 536 0.50 3,950 1,264 0.7816 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2009 5,050 88.7 2,340 445 0.46 3,160 253 0.6316 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2010 5,050 69.8 2,660 2,341 0.53 3,760 2,933 0.7416 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2011 5,050 73.4 2,480 769 0.49 3,440 894 0.6816 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2012 5,050 50.3 1,110 200 0.22 1,610 322 0.3216 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2013 5,050 63.4 1,700 374 0.34 2,360 307 0.4717 Kalamazoo River near Augusta, Mich. (upper) 04105707 2004 2,230 21.9 693 312 0.31 1,170 562 0.5217 Kalamazoo River near Augusta, Mich. (upper) 04105707 2009 2,230 31.3 773 85 0.35 722 238 0.3217 Kalamazoo River near Augusta, Mich. (upper) 04105707 2011 2,230 27.8 1,390 306 0.62 1,150 322 0.5218

St. Joseph River at Napier Ave at St. Joseph, Mich. 

(lower) 04102080 2005 11,000 107.1 474 119 0.04 1,250 163 0.11

18

St. Joseph River at Napier Ave at St. Joseph, Mich. 

(lower) 04102080 2011 11,000 139.5 4,690 375 0.43 5,280 1,214 0.48

19 St. Joseph River at Mottville, Mich. (upper) 04099000 2006 4,830 49.9 650 286 0.13 612 300 0.1319 St. Joseph River at Mottville, Mich. (upper) 04099000 2010 4,830 48.2 880 757 0.18 597 167 0.1220 River Raisin at Monroe, Mich. 04176540 2003 2,750 17.2 992 615 0.36 1,240 707 0.4520 River Raisin at Monroe, Mich. 04176540 2008 2,750 34.9 2,010 744 0.73 1,310 511 0.4820 River Raisin at Monroe, Mich. 04176540 2013 2,750 20.4 1,830 1,867 0.67 2,020 2,384 0.7321 Huron River at Rockwood, Mich. 04175120 2002 2,200 13.1 156 44 0.07 560 106 0.2521 Huron River at Rockwood, Mich. 04175120 2007 2,200 18.8 594 119 0.27 862 224 0.3921 Huron River at Rockwood, Mich. 04175120 2012 2,200 15.1 280 67 0.13 334 147 0.15
Appendix 2 73

Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued[USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan]

Watershed 

number

Station name

USGS 

station 

number

Year

Drainage 

area, 

(km2)

Annual 

mean 

discharge, 

(m3/s)

Chromium Lead

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2)

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2)

22 River Rouge at River Rouge, Mich. 04168550 2005 1,200 11.6 405 117 0.34 686 192 0.5722 River Rouge at River Rouge, Mich. 04168550 2010 1,200 10.7 832 191 0.69 999 180 0.8323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2002 1,900 13.1 1,190 393 0.63 1,650 792 0.8723 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2003 1,900 13.1 2,260 1,469 1.19 3,250 2,210 1.7123 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2004 1,900 19.2 3,050 1,281 1.61 3,790 1,327 1.9923 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2005 1,900 16.3 691 228 0.36 975 293 0.5123 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2006 1,900 22.6 1,850 352 0.97 2,170 521 1.1423 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2007 1,900 16.7 1,210 424 0.64 1,210 508 0.6423 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2008 1,900 23.1 1,260 328 0.66 1,150 288 0.6123 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2009 1,900 31.6 2,220 444 1.17 2,430 778 1.2823 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2010 1,900 14.8 827 215 0.44 843 287 0.4423 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2011 1,900 29.4 3,820 1,146 2.01 6,130 2,636 3.2323 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2012 1,900 12.9 701 322 0.37 772 625 0.4123 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2013 1,900 19.6 1,590 270 0.84 1,750 350 0.9225 Flint River near Fosters, Mich. 04149000 2003 2,990 15.2 1,220 720 0.41 2,330 1,584 0.7825 Flint River near Fosters, Mich. 04149000 2008 2,990 29.2 1,670 284 0.56 2,150 602 0.7225 Flint River near Fosters, Mich. 04149000 2013 2,990 31.9 4,120 2,472 1.38 5,550 3,608 1.8626 Cass River near Bridgeport, Mich. 04152002 2006 2,350 26.5 1,380 649 0.59 1,290 839 0.5526 Cass River near Bridgeport, Mich. 04152002 2011 2,350 24.3 1,630 245 0.69 1,040 291 0.4427 Shiawassee River near Fergus, Mich. 04145000 2005 1,650 13.4 77 23 0.05 115 33 0.0727 Shiawassee River near Fergus, Mich. 04145000 2010 1,650 10.3 453 168 0.27 315 107 0.1928

Tittabawassee River at Center Road near Saginaw, 

Mich. 04156510 2002 6,550 51.1 1,300 468 0.20 1,430 543 0.22

28

Tittabawassee River at Center Road near Saginaw, 

Mich. 04156510 2007 6,550 54.9 2,100 231 0.32 1,910 611 0.29

28

Tittabawassee River at Center Road near Saginaw, 

Mich. 04156510 2012 6,550 46.5 929 307 0.14 554 127 0.08
74 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued [USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan] Water- shed number Station name USGS station number Year Drainage area, (km2

)

Annual 

mean 

discharge, 

(m3/s)

Chromium Lead

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

29 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2002 16,100 124.3 6,240 5,928 0.39 7,990 10,067 0.5029 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2003 16,100 69.8 1,990 418 0.12 2,530 202 0.1629 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2004 16,100 152.3 10,300 4,017 0.64 13,500 6,075 0.8429 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2005 16,100 121.5 1,560 452 0.10 2,830 566 0.1829 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2006 16,100 184.4 12,100 5,082 0.75 15,800 14,536 0.9829 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2007 16,100 125.5 6,550 2,489 0.41 4,360 1,918 0.2729 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2008 16,100 146.2 11,300 6,780 0.70 8,680 3,993 0.5429 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2009 16,100 192.2 9,740 3,312 0.60 9,220 4,794 0.5729 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2010 16,100 99.6 3,940 1,340 0.24 3,820 2,063 0.2429 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2011 16,100 170.3 11,200 1,232 0.70 10,400 832 0.6529 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2012 16,100 103.8 3,450 1,380 0.21 2,620 943 0.1629 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2013 16,100 182.8 10,300 6,283 0.64 8,960 13,798 0.5630 Au Sable River near Au Sable, Mich. 04137500 2002 4,500 34.6 25 5 0.01 37 11 0.0130 Au Sable River near Au Sable, Mich. 04137500 2003 4,500 32.1 4 8 0.00 47 9 0.0130 Au Sable River near Au Sable, Mich. 04137500 2004 4,500 39.0 73 17 0.02 73 13 0.0230 Au Sable River near Au Sable, Mich. 04137500 2005 4,500 36.7 8 6 0.00 43 9 0.0130 Au Sable River near Au Sable, Mich. 04137500 2006 4,500 42.4 315 129 0.07 65 21 0.0130 Au Sable River near Au Sable, Mich. 04137500 2007 4,500 36.9 527 116 0.12 59 33 0.0130 Au Sable River near Au Sable, Mich. 04137500 2008 4,500 40.7 412 194 0.09 44 8 0.0130 Au Sable River near Au Sable, Mich. 04137500 2009 4,500 40.4 314 110 0.07 41 11 0.0130 Au Sable River near Au Sable, Mich. 04137500 2010 4,500 34.2 165 116 0.04 28 2 0.0130 Au Sable River near Au Sable, Mich. 04137500 2011 4,500 36.9 288 46 0.06 46 7 0.0130 Au Sable River near Au Sable, Mich. 04137500 2012 4,500 34.4 221 57 0.05 48 10 0.0130 Au Sable River near Au Sable, Mich. 04137500 2013 4,500 39.1 517 31 0.11 64 13 0.0131 Thunder Bay at Alpena, Mich. 04135020 2005 3,210 21.0 41 36 0.01 68 19 0.0231 Thunder Bay at Alpena, Mich. 04135020 2010 3,210 19.0 117 51 0.04 47 8 0.0132 Black River near Port Huron, Mich. 04160055 2007 1,770 9.5 1,110 244 0.63 927 241 0.5232 Black River near Port Huron, Mich. 04160055 2012 1,770 6.8 223 114 0.13 167 99 0.09
Appendix 2 75

Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued[USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan]

Watershed 

number

Station name

USGS 

station 

number

Year

Drainage 

area, 

(km2)

Annual 

mean 

discharge, 

(m3/s)

Mercury

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2)

1 Ontonagon River at Ontonagon, Mich. 04040018 2006 3,570 31.5 4.64 0.84 0.001 Ontonagon River at Ontonagon, Mich. 04040018 2008 3,570 29.5 10.90 5.34 0.001 Ontonagon River at Ontonagon, Mich. 04040018 2011 3,570 24.2 3.48 0.59 0.001 Ontonagon River at Ontonagon, Mich. 04040018 2013 3,570 45.7 18.70 9.16 0.012 Menominee River at Menominee, Mich. 04067648 2002 10,500 121.9 28.00 6.16 0.002 Menominee River at Menominee, Mich. 04067648 2007 10,500 63.0 4.80 0.72 0.002 Menominee River at Menominee, Mich. 04067648 2011 10,500 82.3 12.30 2.09 0.002 Menominee River at Menominee, Mich. 04067648 2012 10,500 56.9 4.88 0.78 0.003 Escanaba River at Wells, Mich. 040590345 2005 2,400 17.1 2.69 1.24 0.003 Escanaba River at Wells, Mich. 040590345 2010 2,400 15.1 2.00 0.32 0.004 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 2006 567 4.9 0.68 0.16 0.004 Sturgeon River at County Road 499 at Nahma, Mich. 04057521 2011 567 4.8 1.11 0.12 0.005 Manistique River Above Manistique, Mich. 04057004 2004 3,740 67.2 8.00 1.52 0.005 Manistique River Above Manistique, Mich. 04057004 2009 3,740 42.0 5.13 1.33 0.005 Manistique River Above Manistique, Mich. 04057004 2011 3,740 50.6 6.62 2.45 0.006 Tahquamenon River at Emerson, Mich. 04045510 2004 2,090 29.8 6.00 0.90 0.006 Tahquamenon River at Emerson, Mich. 04045510 2009 2,090 25.3 4.75 0.86 0.007 Pine River near Charles, Mich. 04127925 2004 715 8.3 2.00 0.20 0.007 Pine River near Charles, Mich. 04127925 2009 715 6.9 2.31 0.60 0.008 Cheboygan River at Cheboygan, Mich. 04132052 2005 3,890 34.5 0.53 0.15 0.008 Cheboygan River at Cheboygan, Mich. 04132052 2010 3,890 32.8 0.47 0.10 0.009 Boardman River near Traverse City, Mich. 04127200 2003 699 5.5 0.37 0.10 0.009 Boardman River near Traverse City, Mich. 04127200 2008 699 6.1 0.39 0.35 0.009 Boardman River near Traverse City, Mich. 04127200 2013 699 7.7 0.73 0.28 0.00

10 Manistee River at Parkdale, Mich. 04126010 2004 4,480 62.7 2.00 0.40 0.0010 Manistee River at Parkdale, Mich. 04126010 2009 4,480 67.4 2.57 0.28 0.00

11 Pere Marquette River at Scottville, Mich. 04122500 2005 1,760 20.7 0.88 0.20 0.0011 Pere Marquette River at Scottville, Mich. 04122500 2010 1,760 18.1 1.18 0.28 0.00
76 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued [USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan] Water- shed number Station name USGS station number Year Drainage area, (km2

)

Annual 

mean 

discharge, 

(m3/s)

Mercury

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

12 Muskegon River near Bridgeton, Mich. (lower) 04122030 2002 6,420 56.1 1.83 0.37 0.0012 Muskegon River near Bridgeton, Mich. (lower) 04122030 2003 6,420 44.8 1.83 0.60 0.0012 Muskegon River near Bridgeton, Mich. (lower) 04122030 2004 6,420 73.2 5.00 0.80 0.0012 Muskegon River near Bridgeton, Mich. (lower) 04122030 2005 6,420 57.6 1.51 0.36 0.0012 Muskegon River near Bridgeton, Mich. (lower) 04122030 2006 6,420 76.5 14.10 17.34 0.0012 Muskegon River near Bridgeton, Mich. (lower) 04122030 2007 6,420 59.6 2.42 0.68 0.0012 Muskegon River near Bridgeton, Mich. (lower) 04122030 2008 6,420 63.7 2.72 0.46 0.0012 Muskegon River near Bridgeton, Mich. (lower) 04122030 2009 6,420 72.2 3.79 0.45 0.0012 Muskegon River near Bridgeton, Mich. (lower) 04122030 2010 6,420 51.2 1.48 0.16 0.0012 Muskegon River near Bridgeton, Mich. (lower) 04122030 2011 6,420 65.1 2.90 0.32 0.0012 Muskegon River near Bridgeton, Mich. (lower) 04122030 2012 6,420 57.4 2.28 0.32 0.0012 Muskegon River near Bridgeton, Mich. (lower) 04122030 2013 6,420 73.5 5.09 1.07 0.0013 Muskegon River near Hersey, Mich. (upper) 04121621 2006 4,250 44.7 4.64 0.84 0.0013 Muskegon River near Hersey, Mich. (upper) 04121621 2011 4,250 35.7 3.48 0.59 0.0014 Grand River near Eastmanville, Mich. (lower) 04119400 2002 13,700 105.7 13.00 4.55 0.0014 Grand River near Eastmanville, Mich. (lower) 04119400 2003 13,700 73.8 15.00 6.75 0.0014 Grand River near Eastmanville, Mich. (lower) 04119400 2004 13,700 135.7 25.00 6.75 0.0014 Grand River near Eastmanville, Mich. (lower) 04119400 2005 13,700 104.7 8.02 2.73 0.0014 Grand River near Eastmanville, Mich. (lower) 04119400 2006 13,700 144.2 33.40 21.04 0.0014 Grand River near Eastmanville, Mich. (lower) 04119400 2007 13,700 122.9 14.60 4.38 0.0014 Grand River near Eastmanville, Mich. (lower) 04119400 2008 13,700 163.0 21.20 4.88 0.0014 Grand River near Eastmanville, Mich. (lower) 04119400 2009 13,700 186.2 29.70 4.75 0.0014 Grand River near Eastmanville, Mich. (lower) 04119400 2010 13,700 117.6 17.60 7.04 0.0014 Grand River near Eastmanville, Mich. (lower) 04119400 2011 13,700 170.7 22.30 4.68 0.0014 Grand River near Eastmanville, Mich. (lower) 04119400 2012 13,700 105.8 13.10 5.37 0.0014 Grand River near Eastmanville, Mich. (lower) 04119400 2013 13,700 154.7 30.80 10.78 0.00
Appendix 2 77

Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued[USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan]

Watershed 

number

Station name

USGS 

station 

number

Year

Drainage 

area, 

(km2)

Annual 

mean 

discharge, 

(m3/s)

Mercury

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2)

15 Grand River at Ionia, Mich. (upper) 04116000 2006 7,360 75.0 12.00 4.92 0.0015 Grand River at Ionia, Mich. (upper) 04116000 2011 7,360 90.6 18.40 0.92 0.0016 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2002 5,050 34.5 6.21 0.81 0.0016 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2003 5,050 43.3 9.00 1.44 0.0016 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2004 5,050 59.9 10.30 1.24 0.0016 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2005 5,050 55.8 6.91 0.97 0.0016 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2006 5,050 62.0 9.81 2.55 0.0016 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2007 5,050 60.2 9.18 3.30 0.0016 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2008 5,050 85.7 14.10 1.27 0.0016 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2009 5,050 88.7 14.60 1.75 0.0016 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2010 5,050 69.8 13.60 3.40 0.0016 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2011 5,050 73.4 14.20 2.27 0.0016 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2012 5,050 50.3 8.40 2.35 0.0016 Kalamazoo River at New Richmond, Mich. (lower) 04108660 2013 5,050 63.4 12.00 1.44 0.0017 Kalamazoo River near Augusta, Mich. (upper) 04105707 2004 2,230 21.9 4.00 1.00 0.0017 Kalamazoo River near Augusta, Mich. (upper) 04105707 2009 2,230 31.3 3.60 0.97 0.0017 Kalamazoo River near Augusta, Mich. (upper) 04105707 2011 2,230 27.8 5.38 0.81 0.0018

St. Joseph River at Napier Ave at St. Joseph, Mich. 

(lower) 04102080 2005 11,000 107.1 5.20 0.73 0.00

18

St. Joseph River at Napier Ave at St. Joseph, Mich. 

(lower) 04102080 2011 11,000 139.5 25.00 6.75 0.00

19 St. Joseph River at Mottville, Mich. (upper) 04099000 2006 4,830 49.9 3.38 1.45 0.0019 St. Joseph River at Mottville, Mich. (upper) 04099000 2010 4,830 48.2 3.39 1.22 0.0020 River Raisin at Monroe, Mich. 04176540 2003 2,750 17.2 2.92 1.52 0.0020 River Raisin at Monroe, Mich. 04176540 2008 2,750 34.9 4.51 1.26 0.0020 River Raisin at Monroe, Mich. 04176540 2013 2,750 20.4 5.18 6.27 0.0021 Huron River at Rockwood, Mich. 04175120 2002 2,200 13.1 0.73 0.15 0.0021 Huron River at Rockwood, Mich. 04175120 2007 2,200 18.8 1.06 0.22 0.00
78 Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued [USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan] Water- shed number Station name USGS station number Year Drainage area, (km2

)

Annual 

mean 

discharge, 

(m3/s)

Mercury

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2

)

21 Huron River at Rockwood, Mich. 04175120 2012 2,200 15.1 0.73 0.22 0.0022 River Rouge at River Rouge, Mich. 04168550 2005 1,200 11.6 1.12 0.18 0.0022 River Rouge at River Rouge, Mich. 04168550 2010 1,200 10.7 1.92 0.38 0.0023 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2002 1,900 13.1 3.29 1.32 0.0023 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2003 1,900 13.1 5.80 3.83 0.0023 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2004 1,900 19.2 8.00 3.12 0.0023 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2005 1,900 16.3 2.03 0.69 0.0023 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2006 1,900 22.6 5.76 1.56 0.0023 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2007 1,900 16.7 2.82 1.35 0.0023 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2008 1,900 23.1 3.36 1.04 0.0023 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2009 1,900 31.6 6.40 1.73 0.0023 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2010 1,900 14.8 1.91 0.42 0.0023 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2011 1,900 29.4 11.20 3.81 0.0123 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2012 1,900 12.9 2.11 1.50 0.0023 Clinton River at Gratiot Avenue at Mt. Clemens, Mich. 04165553 2013 1,900 19.6 4.23 1.10 0.0025 Flint River near Fosters, Mich. 04149000 2003 2,990 15.2 4.75 2.71 0.0025 Flint River near Fosters, Mich. 04149000 2008 2,990 29.2 4.12 0.78 0.0025 Flint River near Fosters, Mich. 04149000 2013 2,990 31.9 12.40 6.57 0.0026 Cass River near Bridgeport, Mich. 04152002 2006 2,350 26.5 4.70 1.27 0.0026 Cass River near Bridgeport, Mich. 04152002 2011 2,350 24.3 5.50 0.99 0.0027 Shiawassee River near Fergus, Mich. 04145000 2005 1,650 13.4 0.43 0.15 0.0027 Shiawassee River near Fergus, Mich. 04145000 2010 1,650 10.3 1.24 0.56 0.0028

Tittabawassee River at Center Road near Saginaw, 

Mich. 04156510 2002 6,550 51.1 6.21 1.06 0.00

28

Tittabawassee River at Center Road near Saginaw, 

Mich. 04156510 2007 6,550 54.9 6.04 0.54 0.00

28

Tittabawassee River at Center Road near Saginaw, 

Mich. 04156510 2012 6,550 46.5 3.16 0.66 0.00
Appendix 2 79

Appendix 2. Loads for Water Chemistry Monitoring Program by site, constituent, and year.—Continued[USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; kg/yr, kilogram per year; ±, 95 percent confidence level of estimate; kg/yr/km2, kilogram per year per square kilometer; Mich., Michigan]

Watershed 

number

Station name

USGS 

station 

number

Year

Drainage 

area, 

(km2)

Annual 

mean 

discharge, 

(m3/s)

Mercury

Load, 

(kg/yr)

Load 

uncertainty 

(±kg/yr)

Yield 

(kg/yr/km2)

29 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2002 16,100 124.3 19.00 21.09 0.0029 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2003 16,100 69.8 7.00 0.42 0.0029 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2004 16,100 152.3 64.00 17.28 0.0029 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2005 16,100 121.5 8.09 1.54 0.0029 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2006 16,100 184.4 69.40 46.50 0.0029 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2007 16,100 125.5 15.60 8.58 0.0029 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2008 16,100 146.2 25.00 10.00 0.0029 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2009 16,100 192.2 34.40 14.79 0.0029 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2010 16,100 99.6 12.50 7.88 0.0029 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2011 16,100 170.3 32.40 4.86 0.0029 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2012 16,100 103.8 9.13 5.75 0.0029 Saginaw River at Weadock Road at Essexville, Mich. 04157065 2013 16,100 182.8 41.00 30.34 0.0030 Au Sable River near Au Sable, Mich. 04137500 2002 4,500 34.6 0.37 0.20 0.0030 Au Sable River near Au Sable, Mich. 04137500 2003 4,500 32.1 0.37 0.10 0.0030 Au Sable River near Au Sable, Mich. 04137500 2004 4,500 39.0 1.00 0.10 0.0030 Au Sable River near Au Sable, Mich. 04137500 2005 4,500 36.7 0.39 0.12 0.0030 Au Sable River near Au Sable, Mich. 04137500 2006 4,500 42.4 0.85 0.08 0.0030 Au Sable River near Au Sable, Mich. 04137500 2007 4,500 36.9 0.55 0.10 0.0030 Au Sable River near Au Sable, Mich. 04137500 2008 4,500 40.7 0.58 0.15 0.0030 Au Sable River near Au Sable, Mich. 04137500 2009 4,500 40.4 0.58 0.12 0.0030 Au Sable River near Au Sable, Mich. 04137500 2010 4,500 34.2 0.34 0.02 0.0030 Au Sable River near Au Sable, Mich. 04137500 2011 4,500 36.9 0.54 0.15 0.0030 Au Sable River near Au Sable, Mich. 04137500 2012 4,500 34.4 0.47 0.09 0.0030 Au Sable River near Au Sable, Mich. 04137500 2013 4,500 39.1 0.64 0.12 0.0031 Thunder Bay at Alpena, Mich. 04135020 2005 3,210 21.0 0.77 0.44 0.0031 Thunder Bay at Alpena, Mich. 04135020 2010 3,210 19.0 0.57 0.17 0.0032 Black River near Port Huron, Mich. 04160055 2007 1,770 9.5 2.82 0.82 0.0032 Black River near Port Huron, Mich. 04160055 2012 1,770 6.8 0.73 0.45 0.00
For additional information contact:

Director, Upper Midwest Water Science Center

U.S. Geological Survey

6520 Mercantile Way

Suite 5

Lansing, MI 48911

(517) 887-1156

For additional information visit https://mi.water.usgs.gov/

Publishing support provided by the 

Madison and Rolla Publishing Service Centers

Hoard and others—Temporal Trends in Water-Quality Constituent Concentrations and Annual Loads of Chemical Constituents—Scientific Investigations Report 2017–5147

ISSN 2328-031X (print)

ISSN 2328-0328 (online)

http://doi.org/10.3133/sir20175147