U.S. Department of the Interior

U.S. Geological Survey

USGS Fact Sheet 105–03

July 2003

Nutrients in the Upper Mississippi River: Scientific 

Information to Support Management Decisions

The Upper Mississippi River–

Values and Vulnerability

The Upper Mississippi River (UMR) flows 

south about 1,300 miles from its headwaters 

in Minnesota to its confluence with the Ohio 

River at Cairo, Illinois. The river gains volume 

along its path as it drains nearly 190,000 square 

miles (490,000 km2) of land, extending over 

parts of South Dakota, Minnesota, Wisconsin, 

Iowa, Illinois, and Missouri (fig. 1). 

The UMR is valued as a multiple-use resource 

where commercial navigation, water supply, 

and recreational demands coexist with valued 

natural resources. Some 70–80 million tons 

of commodities are transported on the river 

annually. More than 30 million residents rely 

on river water for uses such as public and 

industrial supplies and power plant cooling. 

The river hosts about 12 million recreational 

visitors annually. When the public has been 

asked to identify priorities for the river, 

however, environmental uses were considered 

more important (Carlson, 1999). The river is 

home to a wide variety of wildlife, fish, and 

aquatic invertebrates. Added to these yearround residents are the many bird species 

that migrate through the corridor or stop 

seasonally to breed or overwinter (fig. 2). The 

fact that three major National Wildlife Refuge 

Figure 1. The Upper Mississippi River Basin is 

dominated by agricultural land with some forest and 

major urban areas. 

Figure 2. The Upper Mississippi River supports a high 

diversity of wildlife and is a major migration corridor for 

birds.

Science in the Upper Mississippi 

River: Role of the U.S. Geological 

Survey 

The U.S. Geological Survey (USGS) leads 

the Nation in long-term data collection and 

research of natural water systems throughout 

the Nation. As a nonregulatory Federal agency, 

the USGS provides objective science needed 

to resolve difficult or controversial resource 

allocation issues. Also, it has a dedicated focus 

on the UMRB because of the river’s local, 

regional, and national ecological and economic 

importance. Specifically, the USGS

• maintains an established network of 

hydrologic and water-quality monitoring 

sites on the Mississippi River and its 

tributaries; 

• conducts a multitude of individual studies 

assessing interactions among physical, 

chemical, and biological processes; and 

• provides analysis and modeling of the 

linkages between the watershed, the river, 

and aquatic biota.

Such information is essential to the 

preservation of the health and vitality of 

the aquatic ecosystems of the UMRB. 

Figure 3. Average annual nitrogen yields of streams for 

1980–96 (modified from Goolsby and others, 1999). 

complexes and several National Park units have 

been established along the corridor of the UMR 

reflects the river’s importance to the natural 

resources of the Nation. 

Water quality of the UMR is critical to 

the ecological health of the system and is 

intricately linked to the basin’s vast drainage, 

most of which is used for agriculture (fig. 1). 

Nitrogen and phosphorus are abundant in the 

drainage basin because of the widespread 

use of commercial and animal-manure 

fertilizers. In fact, the quantity of nitrogen and 

phosphorous lost from the land to the stream 

(“yields”) in the Upper Mississippi River Basin 

(UMRB) is higher than in any other portion of 

the Mississippi River Basin (fig. 3).

Nitrogen and phosphorus are essential 

nutrients but in excess can be detrimental to 

aquatic health. Specifically, elevated nutrients 

accelerate photosynthesis, which produces 

nuisance growth or “blooms” of algal or other 

plant biomass that can be problematic. First, 

they are unsightly and can impede recreational 

uses and aesthetics. Second, excessive plant 

growth can damage habitats for other biota 

and impair the general ecological health of the 

aquatic ecosystem. Finally, and probably most 

extensive, is the effect of excessive growth 

of algae and other plants on the depletion of 

oxygen. When these plants die, their rapid 

decomposition can consume oxygen at a high 

rate and can result in low concentrations of 

dissolved oxygen (hypoxia). Low dissolved 

oxygen can be highly stressful or even fatal to 

fish and other biota in the river.

Excessive nutrients, along with sediments 

and pathogenic microorganisms, are among 

the leading causes of impaired streams in 

the UMRB. Impaired streams cannot fully 

support aquatic biological communities or 

other designated uses set by states and tribes. 

A Federal regulatory process establishes Total 

Maximum Daily Loads (TMDLs), a legal 

definition of the total quantity (or load) of a 

pollutant that a stream can carry and still meet 

designated uses and fishable or swimmable 

quality levels (U.S. Environmental Protection 

Agency, 2003; http://oaspub.epa.gov/waters/

national_rept.control). 
2 

Adequate monitoring on multiple scales 

and interdisciplinary research is required to 

develop knowledge of water issues and trends, 

specifically to understand nutrient transport 

and the potential effects of nutrients on the 

ecosystem and on human uses of the water. 

Information derived through monitoring and 

research activities provides an improved 

scientific basis for effective management 

policies and strategies to reduce or eliminate 

water-quality problems within the UMRB. 

Also, the information helps with decisions 

involving competing demands for navigation, 

safe drinking water, aquatic ecosystem health, 

irrigation, wetland protection, and recreation. 

Specific applications of the science to local and 

regional decision-making and policy formation 

are many and far-reaching, including 

• implementing and evaluating management 

actions such as agricultural and urban 

management practices, forest and riparian 

buffers, wetland restoration, and water 

diversions to reduce nutrients in the UMR 

main stem;

• assisting states, tribes, and other 

regulatory parties involved in the 

development of TMDLs; and

• providing an understanding of critical 

factors—i.e., basin characteristics, landuse patterns, water management, and 

climate—that affect nutrient sources, 

transport, and loads needed to address 

effects on downstream water users such as 

fisheries in the Gulf of Mexico.

Long-Term Monitoring Programs

The UMRB has benefited from several 

distinct long-term monitoring programs 

that measure streamflow, water quality, and 

biological responses. Long-term monitoring 

provides a quantitative approach to answer the 

question “Are stream conditions getting better 

or worse?” Water resources are constantly 

changing, seasonally and annually, because 

of both natural factors such as climate change 

and human factors such as urbanization. 

Consistent and systematic monitoring over 

the long term is critical to evaluate benefits of 

implemented management plans, controls, and 

strategies. Long-term monitoring programs 

provide a body of data on hydrologic and 

biologic conditions and in-place field sampling 

capabilities that allow focused modeling 

and research studies (discussed later in this 

document) to more cost effectively explain 

regional and national impacts. 

The USGS manages four national or regional 

long-term monitoring programs that provide 

data and information about the UMR (Table 1). 

Each program is designed to meet specific 

needs and objectives and includes different 

parameters, frequencies of collection, and sites. 

Defined and consistent sampling and analysis 

methods are used in each program so the 

monitoring data can identify trends over large 

regions and long periods of time. 

Within the UMRB, the USGS organizes and 

integrates available information over time 

and across physical, chemical, and biological 

aspects of the river system to develop the most 

comprehensive understanding of the UMR. 

This understanding includes all components 

of the hydrologic cycle, interactions among 

the components (such as streamflow and 

groundwater), and responses of the aquatic life 

to water quality and streamflow. Even with the 

resources of these long-term programs, there 

are unmeasured and unexplained processes that 

contribute to the variability observed in the 

UMRB. Unmet needs for research and longterm monitoring can be defined based on gaps 

in our current understanding from the existing 

programs.

About 190 streamflow gaging stations in the 

UMRB (U.S. Geological Survey, 1999b) 

provide continuous (24 hours a day) and, 

frequently, “real-time” (updated at intervals 

of 4 hours or less) streamflow information 

(http://water.usgs.gov/nsip). These gages are 

supported either through the USGS National 

Streamgaging Network (NSN: some sites in 

the UMR were established in the late 1800s, 

but most were established in the 1930s) 

or the National Streamflow Information 

Program (NSIP, begun in 1999). Sites in the 

NSN Program are cost-shared with local and 

state cooperators; NSIP sites commonly are 

completely supported with Federal funds. The 

combination of these two programs provides 

streamflow information critical for interstate 

treaties, basin and regional water assessments, 

planning studies, flood forecasting, and waterquality and biological assessments (Hirsch and 

Norris, 2001).

A variety of water-quality and selected 

biological information has been collected 

in the UMR by the National Stream Quality 

Accounting Network (NASQAN, 1974–

present). Monthly to semi-annual sampling was 

conducted at about 50 sites during the period 

1974–95 to measure long-term changes in 

water quality at the terminus of the country’s 

major watersheds and at most major subbasins. 

NASQAN was refocused in 1996 to increase 

coverage of additional chemicals of concern 

as well as to improve coverage of high flows 

for improved reliability of annual loads that 

can be significantly influenced by relatively 

few days of high flow. From 1996 to present, 

NASQAN continues to sample three locations 

in the main stem UMR (Clinton, Iowa; Grafton, 

Missouri; and the UMR terminus, Thebes, 

Missouri) from 9 to 15 times per year (figs. 5 

and 6). For additional information, access http:

//water.usgs.gov/nasqan.

In contrast to NASQAN, four study areas 

in the UMRB have been examined in much 

more detail by the National Water-Quality 

Assessment (NAWQA) Program: Eastern 

Iowa Basins, Upper Mississippi River Basin 

(smaller than the UMRB defined in this fact 

sheet), Upper Illinois River Basin, and the 

Figure 4. Hypoxia zone in the Gulf of Mexico near the mouth of the Mississippi 

River was roughly the size of Massachusetts in 2002.

Area of Hypoxic Zone (km2) 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995

1996199719981999200020012002

0

5,000

10,000

15,000

20,000

25,000

Hypoxia in the Gulf of Mexico

Chronic loading of nutrientladen water from the 

Mississippi River over the 

last 30 years has produced 

excess algal growth and 

resulted in a large zone of 

hypoxia in the waters of 

the Gulf of Mexico near the 

mouth of the Mississippi 

River (fig. 4; Rabalais and 

others, 1999; Goolsby and 

Battaglin, 2000). Nitrogen 

tends to be the nutrient 

limiting algal growth in 

marine ecosystems and 

the size and frequency 

of the zone of hypoxia is 

correlated to the quantity 

of nitrogen loaded into the 

Gulf of Mexico (Rabalais 

and others, 1999). Recent 

studies (Goolsby and 

others, 1999; Alexander 

and others, 2000) indicate 

that nearly 90 percent of 

nitrogen input to the Gulf 

is from nonpoint-source 

runoff. 
3

Research:

• Refine critical model inputs

• Improve conceptual

 understanding

Monitoring:

• Evaluate status and trends

• Provide input and calibration of models

Modeling:

• Represent complex systems

• Test hypotheses and scenarios

 for monitoring and research

• Extrapolate in space/time

Scientific Approach to Providing Information For Managing Natural 

Resources in the Upper Mississippi River Basin

Included in U.S. Geological Survey (USGS) investigations are long-term monitoring programs, 

regional modeling studies for estimating and predicting water and nutrient transport in the 

Upper Mississippi River, and research that focuses on processes affecting transformations and 

transport of nitrogen and phosphorus in streams and river systems. Numerous smaller-scale 

studies of water resources are conducted throughout the basin as part of cooperatively funded 

efforts among USGS and other agencies to develop practical solutions to local water problems. 

All of these components work together to provide information in the management decision 

process to resolve biological, land, and water resource use conflicts.

Table 1. Summary of U.S. Geological Survey monitoring programs on the Upper Mississippi River and tributaries.

Program

Years of operation 

in UMR

Number of sample

sites/study areas

Frequency of

sampling

(times/year) Physical features measured Chemical analysis

Biological and ecological

measurements

NSN/NSIP Some 1890s, many 

1930s (ongoing)

~190 Continuous Streamflow none none

NASQAN 1973–95 ~50 1–12 Streamflow, field 

parameters, suspended 

sediment

Major ions, nutrients, carbon, 

dissolved and total trace elements

Fecal coliform, streptococci, 

chlorophyll a and b

1996–present 3 9–15 Streamflow, field 

parameters, suspended

sediment

Carbon, major ions, nutrients,

pesticides, suspended and dissolved

trace elements, nitrogen and oxygen

isotopes

Chlorophyll a

NAWQA Cycle 

I intensive

study

1996–2000 38 sites in 4 study 

areas

15–25 Streamflow, field 

parameters, suspended 

sediment

Major ions, nutrients, pesticides, 

volatile organic compounds, trace 

elements in sediment

Community taxa for fish, 

invertebrates, and algae

NAWQA Longterm trends

2001–present 13 sites in 4 study 

areas

6–12 Streamflow, field 

parameters, suspended

sediment

Nutrients, chloride, sulfate, and 

pesticides

Community taxa for fish,

invertebrates, and algae

LTRMP 1988–present ~120 fixed sites 

river-wide

13–52 Field parameters, velocity, 

water, ice and Secchi depth,

wave depth

Nutrients and selected major ions Chlorophyll a, vegetation cover 

estimates, phytoplankton

1993–present ~840 random sites

within 6 study 

reaches

4 Field parameters, velocity,

water, ice and Secchi depth,

wave depth

Nutrients and selected major ions Chlorophyll a, vegetation cover 

estimates, phytoplankton. Fish, 

vegetation, invertebrate, and land

cover collected for each reach

(1) Not all parameters were measured with every sample nor throughout the life of the program

(2) Nutrients include various forms of nitrogen and phosphorous

(3) Field parameters: Temperature, specific conductance, dissolved oxygen, pH

Lower Illinois River Basin (fig. 5). These areas 

are part of a national program of more than 

50 basins studied. NAWQA was designed to 

describe the condition of our Nation’s streams 

and groundwater, how those conditions change 

over time, and how natural features and 

human activities affect the quality of streams 

and groundwater. By combining information 

on water chemistry, physical characteristics, 

stream habitat, and aquatic life, the NAWQA 

Program provides science-based insights 

for current and emerging water issues and 

priorities (e.g., Sullivan, 1999; Kalkoff and 

others, 2001). During the next decade, these 

NAWQA study areas are scheduled to be 

revisited so that 20 years of data, supplemented 

with detailed process studies, can be used to 

assess long-term trends supported with process 

understanding of those trends. For additional 

information, access http://water.usgs.gov/

nawqa. 

Long-term monitoring data focused on major 

biological, physical, and chemical components 

of the UMR ecosystem are collected by the 

Long Term Resource Monitoring Program 

(LTRMP; U.S. Geological Survey, 1999a). The 

LTRMP began collections in 1988 to provide 

decision makers with the information needed 

to maintain the UMR as a viable multiple-use 

large river ecosystem. Funds are provided by 

the U.S. Army Corps of Engineers for USGS 

to implement the LTRMP in cooperation with 

five Upper Mississippi River System states. 

The LTRMP’s primary water quality focus, 

in contrast to the programs already discussed, 

is on limnological variables known to be 

significant to aquatic habitat. Limnological 

and a suite of biological samples are collected 

in 4 of the 27 navigation pools of the UMR, a 

reach of the Illinois River, and a portion of the 

open, unimpounded river to obtain reach-wide 

estimates for trend detection (fig. 5). Additional 

limnological samples are collected near several 

major tributaries in the UMR. The LTRMP data 

have been particularly useful in documenting 

the finer spatial distribution of nutrients in the 

navigation pools (low-head reservoirs) that 

impound the upper portion of the UMR main 

stem. For additional information, access http:

//www.umesc.er.usgs.gov/ltrmp.

Modeling Nutrient Transport and 

Loads

Effective strategies for managing nutrients 

and water-quality issues require far more 

information than that available from monitoring 

data alone. Continued development of reliable 

computer models improves the ability to 

forecast the fate and transport of nutrients 

for unmonitored locations over different time 

frames, geographic areas, and environmental 

settings. Models are an essential component 

of a cost-effective management strategy over 

broad regions such as the UMRB. 
4 

Several USGS models have been used to 

characterize annual and seasonal nitrogen 

sources and loads in the UMRB. The 

SPARROW model (SPAtially Referenced 

Regression on Watershed Attributes) is used 

to estimate large-scale transport of nitrogen 

(Alexander and others, 2000) through the 

integration of watershed data, including landuse and landscape features, over multiple 

spatial scales. Streamflow and water-quality 

data from the NSN, NASQAN, and NAWQA 

programs are used to calibrate and verify the 

model’s reliability for representing actual 

conditions. The in-stream transport model 

(DAFLOW/BLTM) simulates stream discharge 

and transport of nitrate. With this model, 

Broshears and others (2001) simulate the 

movement of nitrate from the downstream 

boundary of the UMR to the Gulf of Mexico. 

Certain types of hydrologic or water-flow 

models focus on groundwater-derived river 

flow (baseflow), which accounts for most of 

the river flow under low runoff (nonstorm) 

conditions. Outputs from these models can be 

used to compare the importance of different 

water sources and losses. 

Studies of Processes Controlling 

Nutrient Movement, Fluxes, and 

Transformations

Studies of processes provide information for 

improved understanding of nutrient sources, 

cycling, and transport. The information can be 

used to improve model development and aid 

in management decisions for the protection of 

water quality and habitat.

Nitrogen removal 

processes

A number of USGS 

studies are conducted 

in backwater areas 

and pools in the 

UMR to examine 

nitrogen removal 

processes such 

as denitrification. 

Denitrification is an 

important natural and 

beneficial microbial 

process in which 

nitrate is converted to 

a nonreactive nitrogen 

gas that is released 

to the atmosphere. 

Backwater areas and 

pools often provide 

optimal settings 

for denitrification 

because they contain 

anaerobic sediments 

(no oxygen present) 

high in carbon and 

dense beds of aquatic 

plants, but receive 

high amounts of 

nitrate mostly during flooding. Laboratory 

and field experiments have shown that 

introduction of water from the UMR main stem 

to backwater areas results in increased rates 

of sediment denitrification and nitrate uptake 

and removal (Richardson and others, in press; 

Strauss and others, in press). This work has 

shown that a potentially effective management 

option for increasing removal of nitrate is the 

diversion of nitrate-rich water from the main 

stem into backwater areas during nonflooding 

periods. Research on nitrogen processing in 

the UMR has depended on both 

new innovative research and high 

quality nutrient-loading estimates 

provided by the LTRMP.

The potential to manage the UMR 

to remove nitrogen is greater in the 

impounded reaches of the UMR 

than in lower reaches. Above 

St. Louis, Missouri, the UMR is 

managed for navigation through 

impoundment of 27 river reaches 

(pools). Impoundment of the 

floodplain has resulted in a high 

degree of connectivity between 

the main stem and backwaters 

(many of which are managed 

and protected under the National 

Wildlife Refuge System) that 

allows water movement throughout 

the floodplain. In contrast, the 

Lower Mississippi River is 

effectively disconnected from its 

floodplain by flood-control levies, 

and this disconnection prohibits 

nutrient-rich water from interacting with 

the carbon-rich floodplain ecosystems. An 

experimental water-level manipulation within 

one UMR navigation pool that mimicked 

preimpoundment, natural river, fluctuations by 

reducing water levels during late summer has 

shown promise for reducing nitrogen levels 

and improving water quality. USGS scientists 

showed that drying and wetting of sediments 

during such manipulations results in significant 

removal of nitrogen stored in sediments, while 

also increasing abundance of aquatic plants 

critical for fish and wildlife needs (Strauss and 

others, 2003).

Another study of sediment and water chemistry 

at wetland sites near Navigation Pool 8 (near 

La Crosse, Wisconsin) is to determine patterns 

of nitrogen uptake and cycling by floodplain 

wetlands, forest soils, and riverine sediments in 

different seasons and at different river stages. 

Information about this study can be accessed 

at http://www.umesc.usgs.gov/aquatic/

brichardson_5003475.html.

Source characterization using isotopes of 

nitrate and organic matter 

The USGS has conducted research in the 

UMRB to delineate nitrogen and oxygen 

isotope ratios, research that can provide 

useful information about nutrient sources, 

land uses, and nitrogen recycling processes 

that contribute nitrogen to the river (Battaglin 

and others, 2001; Chang and others, 2002). 

The ratio of nitrogen isotopes in aquatic biota 

has proven useful in assessing the relative 

importance of plant uptake and microbial 

denitrification leading to nitrate removal. 

Significant terrestrial sources of nitrate, as well 

as variations in land use, are revealed in the 

patterns of nitrogen and oxygen isotopes of 

nitrate. 

Figure 5. Sampling locations for the National Stream Quality Accounting Network 

(NASQAN), National Water-Quality Assessment Program (NAWQA), and Long Term 

Resource Monitoring Program (LTRMP) in the Upper Mississippi River Basin (Goolsby and 

Battaglin, 2001).

Annual total nitrate flux and mean annual streamflow,

Upper Mississippi River at Thebes, Ill., 1974–99

1974 1979 1984 1989 1994 1999

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Total nitrate

Streamflow

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

450,000

500,000

0

STREAMFLOW, IN THOUSANDS OF CUBIC FEET PER SECOND

TOTAL NITRATE LOAD, IN MILLIONS OF TONS

Figure 6. National Stream Quality Accounting Network monitoring 

since 1974 near Thebes, Illinois, defines stream flow and contaminant 

loads leaving the entire Upper Mississippi River watershed. The annual 

mean stream flow (average flow rate during a 1-year period, measured 

in cubic feet per second), and total nitrate load (mass of total nitrate 

transported downstream during the year) are highly variable from one 

year to another because of drought (for example, 1988–89) and floods 

(for example, 1993). However, total nitrate fluxes leaving the Upper 

Mississippi River Basin have not increased or decreased significantly 

over the 27-year period (Goolsby and Battaglin, 2001).
5

What Management Information 

does the SPARROW Model 

Provide?

Model results (from SPAtially Referenced 

Regression on Watershed [SPARROW]) 

indicate that the sources of nitrogen 

delivered to the Gulf of Mexico are 

predominantly nonpoint sources and of 

the three primary types of land use (forest, 

agriculture, and urban), agricultural lands 

produce the largest yields of nitrogen 

and phosphorus. These model results are 

consistent with results from the Upper 

Mississippi Basin National Water-Quality 

Assessment study (fig. 7). In addition, 

modeling results show that proximity of 

nitrogen sources to large streams and rivers 

increases the amount of nitrogen transported 

to the Gulf (Alexander and others, 2000). 

This is because nitrogen is not removed 

as readily in the large streams and rivers 

by natural processes as in the smaller 

tributaries, and is, therefore, much more 

likely to reach a coastal area. As a result, 

some watersheds in the Mississippi River 

Basin contribute more nitrogen to the Gulf 

than others, despite similar nitrogen sources 

or large distances from the Gulf. This 

knowledge allows nitrogen-control efforts to 

be focused in these more highly contributing 

areas.

10

9

8

7

6

5

4

3

2

1

0

300

270

240

210

180

150

120

90

60

30

0

DISSOLVED NITRATE YIELD, IN THOUSAND

OF POUNDS PER SQUARE MILE PER YEAR

TOTAL PHOSPHORUS YIELD, IN POUNDS

PER SQUARE MILE PER YEAR

Forest Agriculture Urban

Source: Average values from Tables 1-3,

(Stark and others, 2000)

NITRATE NITROGREN

NITRATE NITROGREN

NITRA

PHOSPHORUS

TE NITROGREN

PHOSPHORUS

PHOSPHORUS

Figure 7. Nutrient yields are greatest in streams 

draining agricultural areas (Source: Average values from 

Tables 1–3 [Stark and others, 2001]).

Nitrogen and carbon isotopes, along with 

other chemical and hydrologic measurements, 

have been used to determine the relative 

contributions of terrestrial and aquatic 

particulate matter to the Mississippi River 

(Kendall and others, 2001). Approximately half 

of the nitrogen transported by the Mississippi 

River is in the form of organic matter (Goolsby 

and Battaglin, 2001). If this organic matter 

is available for biological uptake, it may be a 

significant contributor to hypoxia in the Gulf 

of Mexico. Terrestrial sources of particulate 

matter are less available for biological uptake 

water-quality samples from the Mississippi River 

Basin 1997–98: U.S.Geological Survey: WaterResources Investigations Report 01-4095, 57 p. 

Broshears, R.E., Clark, G.M., and Jobson, H., 2001, 

Simulation of stream discharge and transport of 

nitrate and selected herbicides in the Mississippi 

River Basin: Hydrological Processes, v. 15, p.1157–

1167.

Carlson, B.C., 1999, Multi-use management on the 

Upper Mississippi River: public preferences for 

future actions: Master of Science Thesis, University 

of Minnesota, 84 p.

Chang, C.C.Y., Kendall, C., Silva, S.R., Battaglin, 

W.A., and Campbell, D.H., 2002, Nitrate stable 

isotopes: tools for determining nitrate sources among 

different land uses in the Mississippi River Basin: 

Canadian Journal of Fisheries and Aquatic Sciences, 

v. 59, p. 1874–1885. 

Goolsby, D.A., Battaglin, W.A., Lawrence, G.B., 

Artz, R.S., Aulenbach , B.T., Hooper, R.P., Keeney, 

D.R., and Stensland, G.J., 1999, Flux and sources 

of nutrients in the Mississippi–Atchafalaya River 

Basin–Topic 3 report for the integrated assessment 

on hypoxia in the Gulf of Mexico: Silver Spring, 

Maryland, NOAA Coastal Ocean Office, NOAA 

Coastal Ocean Program Decision Analysis Series 

No. 17, 130 p.

Goolsby, D.A., and Battaglin, W.A., 2000, Nitrogen 

in the Mississippi Basin–Estimating sources 

and predicting flux to the Gulf of Mexico: U.S. 

Geological Survey Fact Sheet 135-00.

Goolsby, D.A., and Battaglin, W.A., 2001, Long-term 

changes in concentrations and flux of nitrogen in the 

Mississippi River Basin: Hydrological Processes, 

v. 15, p. 1209–1226.

Groschen, G.E., Harris, M.A., King, R.B., Terrio, 

P.J., and Warner, K.L., 2001, Water quality in the 

Lower Illinois River Basin, Illinois, 1995–98: U.S. 

Geological Survey Circular 1209, 36 p.

Helsel, D.R., and Hirsch, R.M., 1991, Statistical 

methods in water resources: U.S. Geological Survey 

Techniques of Water-Resources Investigations, 

book 4, chap. A3, 510 p.

Hirsch, R.M., and Norris, J.M., 2001, National 

Streamflow Information Program–implementation 

plan and progress report: U.S. Geological Survey 

Fact Sheet FS-048-01.

Kalkoff, S.J., Barnes, K.K., Becher, K.D., Savaco, 

M.E., Schnoebelen, D.J., Sadorf, E.M., Porter, S.D., 

and Sullivan, D.J., 2001, Water quality in the Eastern 

Iowa Basins, Iowa and Minnesota, 1996–98: U.S. 

Geological Survey Circular 1210, 37 p.

Kendall, C., Silva, S.R., and Kelly, V.J., 2001, 

Carbon and nitrogen isotopic compositions of 

particulate organic matter in four large-river systems 

across the United States: Hydrological Processes, 

v. 15, p. 1301–1346. 

Rabalais, N.N., Turner, R.E., Dubravko, J., Dortsch, 

Q., and Wisman, W.J., Jr., 1999, Characterization of 

hypoxia–topic 1 report for the integrated assessment 

on hypoxia in the Gulf of Mexico: NOAA Coastal 

Ocean Program Decision Analysis Series No. 17, 

167 p.

than plankton produced in the river. Isotopic 

analysis adds an important dimension to 

standard chemical and hydrologic data 

allowing for unique interpretations of river 

nutrient dynamics. 

Other USGS Studies of Nitrogen 

Processes

Numerous studies developed to address local 

water-management issues are conducted under 

the Cooperative Water Program with various 

Federal, state, and local entities. These studies 

address a wide range of issues including 

(1) the effectiveness of agricultural and urban 

best-management practices, (2) the influence 

of land-use changes on the water system, 

(3) a comparison of river water quality to 

local and national water-quality standards, and 

(4) the effects of nutrient concentrations on 

aquatic biota. The results of these cooperative 

studies, when analyzed in combination with 

other monitoring, modeling, and process 

research results, can provide the additional 

information needed to make effective 

management decisions. 

Communication and Coordination 

of Efforts–Keys to Effective River 

Conservation

A USGS goal is to deliver credible, timely, and 

relevant science information to inform practical 

and effective water-resource management and 

influence strategies that protect and restore 

water quality in the UMRB. The USGS 

scientists recognize that water resources 

and needs are so complex that a single 

agency cannot address all issues of interest. 

External coordination at all levels, integrating 

multidisciplinary views, is critical for a more 

complete understanding of the watershed and 

for cost-effective management, regulation, 

and conservation of its water resources. 

Partnerships are a vital element of USGS 

programs and studies—not only in enhancing 

the breadth of the science, but also in ensuring 

that USGS information meets the needs of 

local, state, regional, and national stakeholders. 

It is the purpose of this fact sheet and the Upper 

Mississippi Basin Nutrient Initiative Web page 

(http://www.umesc.er.usgs.gov/umbni) to 

describe the roles, resources, and capabilities 

of the USGS, and to enhance communication 

and interaction among those currently involved 

in UMRB studies, both within and outside of 

USGS.

Selected References

Alexander, R.A., Smith, R.B., and Schwarz, G.E., 

2000, Effect of stream channel size on the delivery 

of nitrogen to the Gulf of Mexico: Nature, v. 403, 

p. 758–761.

Battaglin, W.A., Kendall, C., Chang, C.C.Y., Silva, 

S.R., and Campbell, D.H., 2001, Isotopic and 

chemical composition of inorganic and organic 
6

Richardson, W.B., Strauss, E.A., Monroe, E.M., 

Bartsch, L.A., Cavanaugh, J.C., Rabuck, L.D., and 

Soballe, D.M., in press, Denitrification in the Upper 

Mississippi River: rates, controls, and contribution 

to nitrate flux: Canadian Journal of Fisheries and 

Aquatic Sciences.

Stark, J.R., Hanson, P.E., Goldstein, R.M., Fallon, 

J.D., Fong, A.L., Lee, K.E., Kroening, S.E., and 

Andrews, W.J., 2001, Water quality in the Upper 

Mississippi River Basin, Minnesota, Wisconsin, 

South Dakota, Iowa, and North Dakota, 1995–98: 

U.S. Geological Survey Circular 1211, 35 p.

Strauss, E.A., Cavanaugh, J.C., Richardson, W.B., 

Bartsch, L.A., Bruesewitz, D.A., and Soballe, 

D.M., 2003, Nitrogen cycle responses to water 

level manipulations in the Upper Mississippi 

River: 51st Annual Meeting of the North American 

Benthological Society, Athens, Georgia, p. 246–247.

Strauss, E.A., Richardson, W.B., Bartsch, L.A., 

Cavanaugh, J.C., Bruesewitz, D.A., Imker, H.J., 

Heinz, J.A., and Soballe, D.M., in press, Nitrification 

in the Upper Mississippi River: patterns, controls 

and contribution to the nitrate budget: Journal of the 

North American Benthological Society. 

Sullivan, D.J., 1999, Nutrients and suspended solids 

in surface waters of the Upper Illinois River Basin 

in Illinois, Indiana, and Wisconsin, 1978–97: U.S. 

Geological Survey Water-Resources Investigations 

Report 99-4275, 57 p.

U.S. Environmental Protection Agency, 2003, Total 

Maximum Daily Loads: National Section 303(d) 

List Fact Sheet, accessed July 31, 2003, at http:

//oaspub.epa.gov/waters/national_rept.control.

U.S. Geological Survey, 1999a, Ecological status 

and trends of the Upper Mississippi River System, 

1998–A report of the Long Term Resource 

Monitoring Program: U.S. Geological Survey, Upper 

Midwest Environmental Sciences Center, La Crosse, 

Wisconsin, LTRMP 99-T001, 236 p.

U.S. Geological Survey, 1999b, Streamflow 

information for the next century–A plan for the 

National Streamflow Information Program of the 

U.S. Geological Survey: U.S. Geological Survey 

Open-File Report 99-456, 13 p.

Contact Information

For information on the various studies and 

ongoing USGS programs discussed in this 

document, you may refer to the published 

literature cited or contact these program 

offices

Further Research–Filling in the 

Knowledge Gaps

The overall objective of scientific studies 

and data-collection programs is to provide 

information that can be used to better 

understand how an ecosystem functions, 

identify problems that might interfere with 

its normal function, and contribute to the 

development of effective management 

policies and actions to address such 

problems. A large body of knowledge about 

nutrients in the Upper Mississippi River 

Basin (UMRB) has been developed through 

studies over the past 25 years. More specific 

information about watershed processes is 

needed, however, for better understanding 

of nutrient fate and transport in large river 

systems in general and the UMRB in 

particular. Some of the unanswered science 

questions are

• What are the most important controls 

for the movement and transport of 

nutrients from land to tributaries and 

backwaters and then downstream to 

the main stem?

• What level of accuracy is needed in 

information on mapped geographic 

features such as drainage boundaries 

and associated stream reaches to 

produce reliable models of nutrient 

transport?

• How do nutrient chemistry, mobility, 

and toxicity change with changes 

between aerobic and anaerobic 

conditions? Are these changes of 

sufficient magnitude to produce 

significant effects (such as toxicity and 

algal blooms) on ecosystems? 

• How have best-management practices 

in the UMRB affected nutrient 

movement off the land? 

• How does groundwater inflow affect 

nutrient chemistry, mobility, and 

toxicity in the basin and the waters of 

the Upper Mississippi River?

• Some substantial stream-flow changes 

have been observed in tributaries 

of the UMRB. Are these changes 

important in affecting sediment 

and nutrient loading? What are the 

connections, if any, between these 

trends and global climate change?

• What is the effect of nutrient loading 

on the biodiversity and productivity 

of the UMRB ecosystem? Under 

what conditions are phosphorus or 

suspended sediment, rather than 

nitrogen, the primary factors of 

concern with respect to this problem? 

National Programs, including NASQAN, NAWQA, 

and Toxic Substances Hydrology

U.S. Geological Survey

Office of Water Quality

412 National Center

Reston, Virginia 20192

Telephone: (703) 648-6862

Website: http://water.usgs.gov/owq

Cooperative Water Program

U.S. Geological Survey

409 National Center

Reston, Virginia 20192

Telephone: (703) 648-6843

Website: http://water.usgs.gov/coop

Upper Midwest Environmental Sciences Center

U.S. Geological Survey 

2630 Fanta Reed Road

La Crosse, Wisconsin 54603

Telephone: (608) 783-6451

Website: http://www.umesc.er.usgs.gov

Illinois

District Chief

U.S. Geological Survey

221 North Broadway Avenue 

Urbana, Illinois 61801 

Telephone: (217) 344-0037, ext. 3003 

Website: http://il.water.usgs.gov

Iowa

District Chief

U.S. Geological Survey

P.O. Box 1230 

Iowa City, Iowa 52244 

Telephone: (319) 358-3600 

Website: http://ia.water.usgs.gov

Minnesota

District Chief

U.S. Geological Survey 

2280 Woodale Drive 

Mounds View, Minnesota 55112 

Telephone: (763) 783-3100 

Website: http://mn.water.usgs.gov

Missouri

District Chief

U.S. Geological Survey

1400 Independence Road

Rolla, Missouri 65401

Telephone: (573) 308-3664

Website: http://mo.water.usgs.gov

Wisconsin

District Chief

U.S. Geological Survey

8505 Research Way 

Middleton, Wisconsin 53562-3581 

Telephone: (608) 821-3801 

Website: http://wi.water.usgs.gov

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