USGS and citizen monitoring

The water quality of a nearby stream, a watershed, or a large 

river system can be enhanced only by collecting good information about conditions and by responding—most effectively 

at the local level—to that information. Informed citizens of a 

watershed often are in the best 

position to identify priority 

water issues and to understand 

the political, social, and economic context in which those 

issues are addressed. 

USGS works with citizen 

monitors in many watersheds 

across the Nation. Typically, 

watershed associations, such 

as the Alliance for Chesapeake 

Bay and Watershed Committee 

of the Ozarks, plan and conduct the activities of citizen 

monitors. Citizen monitoring enhances the monitoring 

conducted by USGS and other 

federal and state agencies by 

fi lling in geographic gaps or 

by increasing the frequency 

of sampling. Information 

collected by citizen monitors 

can also help USGS and other 

water-resource agencies know 

All of life depends on water, and all of us are citizens of a 

watershed. Our activities and the ways we use our water 

resources and the land adjacent to the water affect the quality 

of our drinking water, our recreational opportunities, and the 

health and diversity of aquatic plants and animals. Our activities also affect whether our rivers and streams will continue to 

be beautiful places to visit and vistas to contemplate.

In this publication, you’ll fi nd information about watersheds 

and about monitoring the quality and quantity of surfacewater resources. You’ll learn how the U.S. Geological Survey 

(USGS) monitors streamfl ow and surface-water quality across 

the Nation and how USGS information can help you learn 

more about your water resources—whether as a citizen of your 

watershed or an active citizen monitor. 

This publication focuses on surface water, but keep in mind 

that surface water and ground water are interconnected. USGS 

also monitors the fl ow and quality of ground water, and investigates surface- and ground-water interactions.

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 077–02

August, 2002

A citizen monitor with Alliance 

for Chesapeake Bay prepares 

to collect water samples near 

the U.S. Naval Academy, where 

submerged aquatic vegetation is being replanted. Some 

citizen data were used in USGS 

studies of these aquatic plants, 

which are vital to the Bay’s 

health. (Photo by Bob Murphy, 

Alliance for Chesapeake Bay.)

October 18, 2002 is the 30th 

anniversary of the Clean 

Water Act—a milestone in our 

Nation’s efforts to protect our 

water resources. As part of the 

“Year of Clean Water” celebrations, USGS is participating in National Water Monitoring Day alongside citizens 

and professionals interested 

in, and working on, water 

issues at the watershed, state, and national levels. For 

more information, go to www.yearofcleanwater.org.

Monitoring Our Rivers and Streams

where to focus their broader data-collection activities and 

analysis. In turn, hydrologists from USGS and other agencies often train citizens during “side-by-side” data-collection 

activities.

To learn about USGS monitoring activities in your state, 

call or e-mail the USGS representative. A list of contacts is at 

water.usgs.gov/district_chief.html.

Understanding your watershed

Natural features, such as topography, defi ne watersheds—land 

areas that receive rain or snow and drain to specifi c surfacewater bodies, such as streams, rivers, lakes, reservoirs, bays, or 

oceans. Both natural and human-induced conditions within the 

watershed are refl ected in the quality of the surface water. 

More and more, water-quality management and policies are 

being developed in terms of the watershed, rather than being 

couched in terms of cultural boundaries, such as counties and 

states. While many federal and state agencies focus on the 

larger river systems and associated watersheds, local agencies 

and citizens usually are concerned with the smaller watersheds 

where they live. Because the smaller watersheds are “nested” 

within the larger river networks, and because many watersheds 

cross jurisdictions, successful watershed management requires 

that everyone work together—citizens and water-resource 

professionals, and local, state, interstate, and national stakeholders.

A standardized watershed classifi cation system—the 

Hydrologic Unit System—was developed in the mid-1970s 

by USGS under the sponsorship of the U.S. Water Resources 

Council. The goal was to delineate and map hydrologic boundaries and enable a variety of organizations and programs to 

share information and coordinate management of watersheds.
To locate and learn about 

your watershed, go to EPA’s 

Water Information Network at 

www.epa.gov/win/.

Click on “Watershed Questions: What is my watershed 

address?” and “Locate Your Watershed.” You can search 

by map, stream name, zip code, county, Tribal nation, 

or other geographic names to fi nd your watershed and 

its hydrologic unit code (HUC). For example, if you live 

in Tennessee and your zip code is 37919, you live in the 

Watts Bar Lake Watershed, which is HUC 06010201. 

Hydrologic units are a topographically defi ned set of watershed boundaries, organized in a nested hierarchy by size. The 

system divides the Nation into 21 regions (representing some 

of our largest rivers, such as the Missouri, Susquehanna, and 

Columbia Rivers), and progressively smaller sub-regions, 

accounting units, and cataloging units. Each cataloging unit 

is assigned an 8-digit code (its hydrologic unit code, or HUC) 

having two digits for each of the four levels.

The 8-digit HUCs are used widely, such as in the U.S. 

Environmental Protection Agency (EPA) Water Information 

Network (described below). The geographical area of the cataloging units is often too large, however, for management at the 

local level, such as for land-use planning. Therefore, USGS, 

U.S. Department of Agriculture, EPA, and other federal agencies and interested states are in the process of subdividing 

cataloging units into watersheds (average size 40,000–250,000 

acres) and sub-watersheds (10,000–40,000 acres). For information on HUC maps and watersheds in your State, call 

1-888-ASK-USGS or go to water.usgs.gov/GIS/huc.html.

• Why long term? Long-term data collection, using consistent and comparable methodology, is critical to identify 

trends or patterns, to try to fi nd out: “Are things getting 

better or worse?” Water quality is constantly changing—

during the day, from day to day, from season to season, and 

from year to year. To distinguish real trends from short-term 

fl uctuations, we need consistent and systematic information over the long term. This is also necessary for evaluating 

environmental strategies and choosing the most costeffective strategies for the future.

• What does biology have to do with water quality?

Biological communities are indicators of stream quality. 

Organisms such as algae, invertebrates (insects, worms, 

and clams), and fi sh have a wide range of sensitivities to 

physical and chemical changes in their habitat. For example, 

increasing algae populations often correlate with higher 

concentrations of nutrients (nitrogen and phosphorus). Other 

indicators of degraded water quality are a preponderance 

of worms and midges, which are “tolerant” of pollution, or 

a fi sh community that is not diverse and abundant or that 

is composed of non-native species. Biological communities also refl ect the overall health of a watershed. Physical 

processes, such as deforestation and fi res, can alter stream 

habitat, hydrology, and stream temperature and can quickly 

degrade biological communities before nutrients and other 

contaminants reach levels that can degrade these communities.

• What does water quantity have to do with water quality?

The quantity of streamfl ow (also called “discharge”) is an 

important factor in determining water quality and, thus, in 

interpreting water-quality data. The potential effects of contaminants on drinking-water supplies and aquatic habitats 

depend largely on the amount of water fl owing in streams. 

You may have heard the outdated adage that “dilution is the 

solution to pollution.” More fl ow, however, usually means 

that rivers and streams are carrying a greater magnitude of 

contaminants and sediment, in part because of overland runoff. When waters carrying these increased loads reach gulfs 

and bays, aquatic plants and animals can be greatly affected, 

particularly if this occurs during the critical life cycles of 

these organisms. 

A “hydrologic context” for your 

monitoring data

Information from USGS monitoring can help you understand 

more about the signifi cance of the conditions you observe or 

measure in your watershed. Several characteristics of USGS 

monitoring provide this “hydrologic context”:

Monitoring is at different scales and in different 

environmental settings

USGS investigates local issues and trends in a particular 

stream or in a particular county, as well as larger regional 

A monitoring protocol

Monitoring is necessary to ensure that our waters can continue 

to support the many different ways we use these resources 

and to track whether protection and restoration measures are 

working. The information gained from monitoring helps with 

prioritizing the issues to be addressed and choosing the geographic areas in which to concentrate, thus helping to ensure 

cost-effective water-resource management.

Effective monitoring is regular, long term, and includes 

biological, physical, and chemical measurements.

• Why regular measurements? Taking a single waterquality measurement will not indicate how the property 

varies over time. For example, if you measure the pH of a 

stream and fi nd that it is 5.5, you might think that the water 

is acidic because of a water-quality problem. But a pH of 5.5 

might be “normal” for that stream. Similarly, one person’s 

normal body temperature may be about 97.5 degrees, but 

another person’s is right at 98.6. As with human temperatures, if the pH of a creek begins to change, then something 

might be affecting the water, and possibly, the water quality. 

So, often, the changes in water measurements are more 

important than the actual measured values.
Technicians are measuring discharge, the volume of water passing a given stream cross section in a given period of time (reported 

as cubic feet per second, or ft3/s). Another type of data collected to 

determine streamfl ow is stage (or “gage height”), the height of the 

water above an arbitrary reference point set at the gaging station. 

Stage measurements are continuously recorded by equipment inside 

a gagehouse located on the stream bank and relayed via telephones 

or satellites to USGS offi ces. It isn’t practical for people to make 

continuous discharge measurements, so daily discharge values 

(provisional “real-time” values reported on the Web) are computed 

on the basis of a mathematical relation between the river’s stage and 

discharge. (Photo by Michael Coakley, USGS.)

Current meter

This “drought map” (available at water.usgs.gov/waterwatch) highlights areas experiencing below-normal streamfl ow levels (lightest 

colored dots) to levels indicating “extreme hydrologic drought” (darkest dots). “Normal” is defi ned in the context of streamfl ow conditions 

that have been recorded at a site at the same time of year over the 

past 30 or more years.

systems, such as the Mississippi River Basin. Methods of 

sampling and analysis are uniform, and monitoring is done at 

sites that are representative of watersheds across the Nation, 

so that comprehensive assessments can be made at larger, even 

national, scales. This multi-scale approach helps to determine 

if certain types of water-quality issues are isolated or pervasive, and allows streams and rivers to be compared to those in 

other geographic and environmental settings. Therefore, the 

data can help answer questions like— 

• Is the pH in my stream typical of streams in the Atlantic 

Coastal Plain?

• Are other streams in the arid west experiencing elevated 

salinity?

• Is a nitrate concentration above 5 parts per million commonly found in other watersheds?

Monitoring is regular and long term

USGS has been collecting data for more than a century at 

some of its monitoring stations. Long-term data collection 

creates a set of baseline data that can be used to assess the signifi cance of observed changes. For example, collecting data on 

our water resources over the long term helps answer questions 

like—

• How high will streams rise if my area experiences a 

100-year fl ood?

• Did implementation of stream buffers and other restoration 

practices work?

• Are streamfl ows in this watershed at historically low or high 

levels?

Nationwide streamfl ow data are available

Currently, USGS regularly collects streamfl ow data at more 

than 7,000 sites (“gaging stations”). Most of the stations are 

funded and operated in cooperation with other federal agencies, such as the U.S. Army Corps of Engineers, and with 

state, Tribal, county, and municipal agencies. Provisional 

data from more than 6,700 of these stations are available 

in “real time” (updated at intervals of 4 hours or less) at 

waterdata.usgs.gov/nwis. 

Access to streamfl ow data allows for more accurate interpretation of water-quality data. An observed trend in water 

quality—for example, increasing concentrations of a contaminant in a stream over a six-month period—may indicate an 

actual water-quality change or may be the indirect result of 

differences in the distribution of fl ow volumes when the water 

samples were collected. 

Nationwide water-quality data are available

USGS collects samples from streams across the Nation and 

analyzes for chemical, physical, and biological properties of 

water, sediment, and tissue. Data are collected for investigations that range from national in scale, such as the National 

Water-Quality Assessment Program (NAWQA), to studies in 

Ø
small watersheds. Typical fi eld measurements (made directly 

in the stream or on the streambank) include pH, water temperature, dissolved oxygen, and turbidity. (USGS scientists, other 

professionals, and citizens will measure these four parameters 

in watersheds across the Nation on National Water Monitoring 

Day, October 18, 2002. Visit water.usgs.gov for more information about these parameters.) 

Other fi eld measurements include specifi c conductance (conductivity), an indirect indicator of dissolved minerals, acids, 

and metals in the water; and alkalinity, an indicator of water’s 

ability to neutralize acids and keep the pH constant. Currently, 

selected fi eld measurements are available in real-time from 

more than 800 USGS sites at waterdata.usgs.gov/nwis/qw.

Other chemical measurements—such as analyses for concentrations of major ions, nutrients, trace elements, pesticides, volatile organic compounds, radioactive chemicals, and 

organic wastewater contaminants—are made in the laboratory. 

The USGS National Water-Quality Laboratory in Denver, 

Colo., specializes in environmental analytical chemistry, 

and features standardized laboratory methods and qualityassurance and quality-control protocols. In addition, the laboratory methods can detect concentrations at very low levels—

commonly 10 to 1,000 times lower than the EPA standards 

and guidelines. These sensitive methods allow for an early 

detection of potentially harmful contaminants before they 

reach levels of concern, and allow for trends to be detected for 

constituents that are diffi cult to measure.

USGS monitoring is for assessment only

USGS has no regulatory responsibilities and focuses on evaluating the entire resource, which may be a source of drinking 

water as well as of water used for industry, irrigation, and recreation. USGS water-quality data thereby complement much 

of the data collected by the States and by EPA, which focus on 

monitoring for compliance with regulations.

Printed on recycled paper

NAWQA biologists are collecting benthic (bottom-dwelling) invertebrates for analysis. USGS also monitors for concentrations of total 

coliform bacteria and viruses; fi sh-tissue contaminants (such as 

mercury, DDT, and dioxin); and algae. (Photo by Denis Sun, USGS.)

JULY 3 JULY 4 JULY 5 JULY 6 JULY 7 JULY 8 JULY 9 JULY 10

USGS 07308500 Red Rv nr Burkburnett, TX 8,000

1,000

100

70

DISCHARGE, IN CUBIC FEET PER SECOND

DISCHARGE

MEDIAN DAILY STREAMFLOW BASED 

ON 41 YEARS OF RECORD

EXPLANATION

�����

�����

�����

�����

�����

�����

�����

�����

�����

������������������������������������������

��������������������������������

������ ������ ������ ������ ������ ������ ������ �������

���������������������������������������

Graphs of real-time discharge values can help you decide if it’s 

a good time for an outing on the river. Discharge data also help 

with interpretation of water-quality data. For example, a precipitous decline in values of specifi c conductance corresponded with 

increasing streamfl ow at the Red River near Burkburnett, TX station, 

on July 6, 2002. This station is one of more than 800 across the Nation 

with real-time data on both water quality and water quantity. 

Visit water.usgs.gov for access to online maps, 

data, and reports, including:

• WaterWatch for maps and graphs of streamfl ow conditions

• NWISWeb (National Water Information System) for realtime and historical water data

• Online Fact Sheets for short, nontechnical reports 

• Online Reports for technical reports

By Martha L. Erwin and Pixie A. Hamilton

Layout and design by Phillip J. Redman

For printed reports and maps 

Call 1-888-ASK-USGS

Or, write to: 

USGS, Information Services

Box 25268 Federal Center

Denver, CO 80225 

Or, fax requests to (303) 202-4693