DEVELOPING ENVIRONMENTAL INDICATORS FOR MINNESOTA

Rivers and Streams The Environmental Indicators Initiative State of Minnesota Funded by the Minnesota Legislature on recommendation of the Legislative Commission on Minnesota Resources Sponsored by The Environmental Quality Board 1998

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Citizens and decision makers use environmental indicators to help effectively manage and protect Minnesota’s rivers and streams. Environmental indicators answer four questions.

river miles dredged, straightened, or influenced by dams or impoundments, the number of industrial and municipal waste treatment facilities, and the percent of the watershed in impervious cover.

What is happening to our rivers and streams?

How does it affect us?

Environmental condition can be assessed using indicators based on ecological characteristics of rivers, including diversity of aquatic insects, percent of river with self-sustaining fish populations, and the percent of stream miles where flow and timing exceed historic range of variation.

Why is it happening?

Indicators of human activities that affect rivers include the percent of

Changes in river health may diminish the flow of benefits. Indicators of how we are affected include the percent of river miles supporting boating and fishing, commercial and recreational fish harvests, and drinking water treatment costs.

What are we doing about it?

Societal strategies to maintain or restore healthy rivers include shoreline vegetation restoration, aquatic 2

habitat improvement, and industrial and municipal waste reduction.

In this chapter we outline important benefits from river and stream ecosystems, the key ecological characteristics that determine the health of rivers and streams, the pressures affecting rivers and streams today, the current status and trends relating to rivers and streams, and the most significant policies and programs that affect Minnesota rivers and streams. Throughout the chapter we give examples of indicators that provide important information about Minnesota rivers and streams.

HIGHLIGHTS

Benefits of Healthy Rivers and Streams • • • • • • • •

Habitat for fish and wildlife Hiking, canoeing, swimming, hunting, and trapping $1.5 billion from recreational fishing Commercial and sportfishing Cooling water for power generation Industrial uses (material processing, sewage treatment) Irrigation water for crops Public water supplies (fire protection, private use)

Important Ecological Characteristics •

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Ecological functioning is governed by the physical characteristics of a river, including the constant movement of materials from upstream to downstream reaches, and the linkages with adjacent backwater and floodplain areas Nutrients and sediment from the streambed and the surrounding watershed govern the chemical characteristics of a river or stream Biological diversity is influenced most by physical and chemical factors in the river

Impacts on Rivers • • • • •

Channel alterations, wetland drainage, and subsurface tiling Commercial and recreational overuse (barge and boating traffic) Exotic species Toxic contamination (PCBs, mercury) Intensive land use (mining, row crops, residential development)

Status and Trends • • •

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Water quality assessed for less than 5% (4,500 miles) of the state’s river and stream miles 22% of assessed river miles met ‘fishable, swimmable’ standards in 1992 6-fold decrease in PCB concentrations in carp from Mississippi River in Twin Cities area, 1973-1991 Mercury and PCB concentrations in over 24 fish species from 3 dozen rivers and streams statewide still exceed levels safe for children and women 76% of Minnesota River survey sites were ranked ‘fair’ to ‘poor’ in overall quality based on data on fish populations 90% of wetlands have been removed from the Minnesota River basin Statewide, 22,000 miles of rivers and streams have been lost to channelization

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Existing Policies and Programs • • • •

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Federal Water Pollution Control Act (Clean Water Act) Minnesota Environmental Policy Act Reinvest in Minnesota Program: restores and improves riparian habitat with land easements Clean Water Partnership Program: helps local governments improve and protect water resources Statewide nonpoint-source management program, led by MPCA, with multiagency involvement Local cleanup and education groups (e.g., Adopt-a-River Program)

BENEFITS FROM RIVERS and STREAMS

Rivers and streams are ecological, economic, and social resources in the Minnesota landscape. Minnesota’s rivers and streams were transportation routes for Native Americans and early European explorers and settlers. Today, the state’s rivers are habitat and travel corridors for wildlife. They also provide food, water (for drinking and irrigation, power production and industrial processing, and transportation), and recreation for humans. Cooling water for power generation, the largest volume use of water in Minnesota (Figure 1), is drawn almost entirely from surface waters, primarily the Mississippi River, and accounts for approximately 69% of statewide water use (MDNR 1995). Public water supplies (for municipal, private, commercial, and cooperative waterworks; fire protection; state parks; and wayside and rest areas) also draw heavily from Minnesota’s rivers, accounting for about 15 percent of statewide water use. In 1993, industrial uses (e.g., agricultural processing, pulp and paper production, mine processing, sand and gravel washing, sewage treatment, petroleum and chemical processing, metal and non-metal processing) constituted 11 percent of the statewide total. Irrigation water pumped from rivers and streams accounted for about 3 percent of the statewide total.

Rivers provide water-based recreation in every region of the state. Fishing is fundamental to Minnesota’s tourism industry, luring thousands of anglers each summer from throughout the United States and generating more than $1.5 billion annually in related expenditures (MDNR 1996). More than half of Minnesota’s 4.3 million residents, about 2.3 million anglers, use the state’s 5,400 fishing lakes and 15,000 miles of fishable streams (including 2,600 miles of trout streams). Fishing, hunting, canoeing, camping, picnicking, hiking, walking, swimming, and general viewing are among the most important uses of Minnesota’s rivers and their corridors (MDNR 1988).

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The protection afforded portions of seven rivers under the state’s Wild, Scenic and Recreational Rivers program attests to the recreational, aesthetic, and spiritual values associated with the state’s rivers and streams. In addition, these pristine rivers serve as ecological benchmarks against which the health of other rivers can be measured.

system for part of their life cycle link rivers to terrestrial systems and also modify the flow of energy and nutrients. Chemical composition and energy levels in rivers also change as runoff carrying nutrients, sediments, and toxic chemicals enters from urban and rural areas. The area and percentage of the watershed with significant soil erosion, the phosphorus content in water and microorganisms, and the nutrient content of sediments are indicators of river health.

Biological productivity

RIVER SYSTEM ECOLOGY

Rivers and streams are part of the hydrologic cycle, a concept used to explain the movement of water around the earth (Figure 2). In this cycle, rivers and streams link terrestrial resources (the watershed or drainage basin) with groundwater resources and the oceans. Because the cycle is continuous, with no beginning or end, each part of the cycle (e.g., runoff, groundwater withdrawals, stream flow alteration, etc.) affects other parts of the cycle (MDNR 1995).

Nutrient cycling

The mineral characteristics of the stream substrate and the watershed from which the water is derived, and the plant and animal materials that enter the water (Tester 1995) determine the nutrient concentrations and other chemical properties of streams. Rivers that flow across limestone or glacial till contain high

concentrations of carbonate, calcium, and magnesium (hard water) and usually support a larger number and greater diversity of river organisms than other rivers. Rivers that flow through coniferous forests and peatland areas are more acidic and support fewer organisms. The input of organic materials from adjacent uplands is strongly influenced by land management practices and natural conditions. As much as 99 percent of all organic matter in the upper and middle reaches of streams originates in the surrounding watershed. Rivers flow continuously, transporting nutrients and energy from upstream to downstream areas. Consequently, headwaters are poorer in nutrients than downstream reaches. Variation in flow determines to a large extent how much and how quickly nutrients and energy are transported. Semi-aquatic organisms (e.g., beaver, muskrat, heron, ducks, geese and other birds, frogs, and turtles) that feed or live in the river 5

The physical structure of the river (habitat complexity), the chemical characteristics of river water, and position along the length of the river (Figure 3) all influence plant and animal growth in the river channel. For example, rocky substrates, submerged logs, and backwater areas are elements of habitat complexity that allow some plants and animals to flourish. Meeting the habitat needs of organisms is essential to their productivity. Oxygen, nitrogen, and phosphorus content are especially important in determining the ability of water to sustain plants and animals. Where fertilizers enter a river, levels of nitrogen and phosphorus may be high enough to increase biological productivity significantly. However, as this abundant plant and animal matter decays, oxygen in the water may be depleted and productivity may decrease.

Productivity varies naturally with distance downstream. In the headwaters, shade often limits growth of large aquatic plants and algae. In the slower-moving, sunlit middle stretch of the river, algae and large plants account for much of the river’s primary productivity. In the lower reaches, low light conditions (from suspended sediments and organic particles) limit productivity, but since the water is moving slowly, algae, aquatic plants, soil insects, freshwater mussels, and fish that feed on algae (e.g., buffalo, carp) may be

common. In most rivers, animal and plant productivity varies with the geology and other physical and chemical properties of the watershed (Figure 4). The productivity of plant and animal populations, e.g., the abundance of key species of aquatic plants, the percentage of river miles with self-sustaining populations of top fish carnivores, recreational/ commercial fish harvests, and populations of fish-eating birds can be indicators of river system productivity.

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Biological diversity

Physical and chemical factors also help determine river biodiversity (Tester 1995). Rivers offer a variety of physical conditions, including deep-water pools, shallow rockybottomed riffles, vegetated spawning areas, small side channels, and fastmoving scour pools. Environmental conditions range from shaded to well lit, from rich to depleted in oxygen, and from turbid to clear. Slow-moving backwaters, protected areas near woody debris, riffles, deep pools, and floodplains provide the unique conditions that support different types of plant and animal species. The channel itself may be very narrow or wide, deep or shallow, gently sloping or steep. Structurally diverse channels provide a greater number of habitat types. A river system with a diversity of plants and animals also supports a variety of land animals valued by humans.

Changes in watershed characteristics (e.g., conversion of grassland to row crops, urbanization) or stream channels (e.g., damming, dredging, straightening) tend to reduce the diversity of conditions found in rivers. For example, research in Iowa showed that straightened or channelized streams had fewer species than unchannelized reaches and less than 10 percent of the fish biomass (i.e., weight of all fish) found in unchannelized reaches (Paragamian 1990). Indicators of biological diversity include in-stream habitat diversity, and percentage of stream miles not dredged, straightened, or influenced by dams or impoundments.

Natural disturbances

Rivers are constantly changing and thus are physically and biologically complex systems. This complexity provides the foundation for their biological productivity and diversity. Natural disturbances are important change agents. Seasonal flooding removes silt deposits from gravel used by many fish species for spawning and redeposits it on floodplains, where it replenishes soil productivity. Floods also provide seasonal feeding, breeding, and nursery areas for many fish (e.g., northern pike), amphibians, and waterfowl. Similarly, occasional drought and periods of low flow allow time for riparian vegetation to

stabilize eroding stream banks, creating shade and deep pool habitats that benefit many species. Flooding and drought are natural disturbances characteristic of rivers and streams, and as such are essential components of healthy river ecosystems (Figure 5). Changes in the frequency or intensity of disturbance events can serve as an indicator of humancaused changes in the surrounding watershed or of global climate change. As the nature of these disturbances changes, plant and animal communities living in the channel may change as well. Indicators of land conversions (percentage of land converted from grasslands and forests to other uses) and hydrological changes (percentage of stream miles where flow and timing significantly exceed historic range of variation) can provide information about the health of the river ecosystem.

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PRESSURES ON RIVERS AND STREAMS

Rivers reflect the health of the watershed they drain. Therefore, changes in surrounding watersheds (e.g., land-use conversions), alterations in the watercourse itself, and intensified recreational uses may affect the health of the state’s rivers.

Channel alterations

Channelization, or the straightening of natural streams, to drain low-lying areas for farming and other activities is common in Minnesota. Channelization also prevents flooding (upstream) by expediting the movement of water downstream. Negative ecological impacts may include excessive peak flows downstream and reduced habitat diversity. Riparian dikes and levees that are often associated with channelization isolate the stream from its floodplain and prevent natural nutrient and energy flows and movement of organisms. Dams and similar permanent barriers limit fish movement, reduce free-flowing river habitat, cause fish mortality from pumps and turbines, and alter flows and water quality both upstream and downstream of the impoundments (Ward and Stanford 1979). These structural changes often isolate species from critical habitat required at different stages of their life cycles. For example, important game

species, including walleye, northern pike, and channel catfish, spawn and rear young in smaller tributaries and use main stem areas during summer low flow and in winter. Greater fluctuations in water levels (higher peak flows and lower minimum flows), flooding of upstream landscapes, increased streambank erosion and flooding during peak flow periods are indicators of flow alterations.

Intensive land use

Intensive land uses (such as residential and industrial development, road construction, row crop and irrigation agriculture, timber clearing, mining, and golf courses) that remove natural vegetation and increase impervious surfaces (e.g., asphalt) may dramatically alter the hydrologic cycle by causing extreme (high and low) flows and erosion. Erosion is a serious threat to streams and rivers, especially in agricultural and

developing areas. Excessive siltation and sedimentation increase turbidity, reduce the growth of desirable aquatic plants, cover productive stream-bottom habitat, damage eggs and gills of fish, and increase nutrients and bacteria in surface waters. Excess phosphorus and nitrogen also threaten river and stream health statewide. Urban runoff, failing septic systems, sewage discharges, and agricultural fertilizer and manure contribute to high amounts of these nutrients (Cannon River Watershed Partnership 1996) and high concentrations of fecal bacteria in rivers. The algal blooms, oxygen depletion, loss of game fish, and contamination of groundwater that accompany nutrient enrichment reduce boating and swimming opportunities and create human health problems. The percentage of river miles meeting water-quality standards for specific uses and the percentage of the watershed in permanent native vegetation provide information essential to assessing river and stream health.

Commercial and recreational overuse

Channel modifications (e.g., dredging, debris removal) to accommodate commercial barges and boats have altered natural flows and channel habitats (UMRCC 1993) and created conditions that favor exotic and nuisance species (e.g., carp, zebra mussels, purple loosestrife) in the Mississippi River. Barge traffic alters current velocities 8

and interferes with the movement and feeding of young fishes and other aquatic organisms. Waves from boats and barges, combined with the increased wind and wave energy across the open pools, may increase turbidity and shoreline erosion, reduce water quality, and damage critical island habitats. Recreational use, exotic species populations, and shoreline erosion help explain trends in river and stream health.

Environmental contaminants

Toxic contaminants, particularly mercury and PCBs, impair the health and public use of streams within all major river basins of the state. Cancer and nervous system damage in humans are potential consequences of these chemicals which come from landfills, incinerators, power plants, industrial processes, urban and agricultural runoff, and airborne dust. Although PCBs were banned in 1976, they do not decompose rapidly and dangerously high concentrations remain in water and sediment. Groundwater contamination, fish consumption advisories (Figure 6), and abnormalities and tumors in fish are potential consequences (and indicators) of mercury and PCBs in the environment.

STATUS AND TRENDS Water quality

In 1992, 22 percent of the assessed river miles (only 4 percent of Minnesota’s 92,000 river miles were assessed) met fishable and swimmable water-quality standards (Minnesota Planning 1996). Nonpoint-source pollution related to intensive land uses (e.g., agricultural runoff, urban construction, feedlots) is an important factor contributing to the failure of some waters to meet standards (Minnesota Environmental Quality Board 1988). According to a more recent survey of rivers by the Minnesota Pollution Control Agency (MPCA), water quality was

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unchanged for 63 percent, improved for 32 percent, and degraded for 5 percent (Figure 7; MPCA 1995). This is a net improvement for Minnesota rivers. Because much of Minnesota drains to the Mississippi River, water quality downstream of the Twin Cities may be a good integrated measure of environmental health. Water-quality (dissolved oxygen, total ammonia, total phosphorus, biological oxygen demand) improved over the past sixteen years (1976-80 to 1988-92; Figure 8; MPCA 1993) largely due to upgraded municipal and industrial wastewater treatment and increased efforts to reduce pollution in runoff.

Lower concentrations of toxic contaminants in fish from the Mississippi River also suggest improved river health. For example, PCB concentrations in carp from the Twin Cites area declined nearly sixfold from 1973 to 1991 (Figure 9; MPCA 1995). Despite this improvement, current PCB levels in carp and many other fish species from the Mississippi exceed safety standards for human consumption (MDH 1996). In addition, mercury and PCB contamination in two dozen fish species limit consumption in approximately three dozen streams and rivers statewide.

Watershed and channel alterations

Nonpoint-source pollution from intensive land uses and extensive alteration of stream channels and floodplains affect the health of many Minnesota rivers. The Minnesota River, for example, one of the state’s most polluted waters, receives much of its pollution from nonpoint sources (MPCA 1994). Its fish communities reflect the problem (76 percent of 116 survey sites were ranked fair to very poor in overall quality). In the Minnesota River watershed, stream channelization, ditching, and tiling have eliminated over 90 percent of the wetlands, reduced water quality, and exacerbated flow extremes during dry and wet periods (Figure 5). In the Red River basin, channelization and more than 500 dams have reduced the amount of stream habitat and habitat diversity, blocked migration pathways, increased erosion and flood flows, and degraded water quality (Aadland 1997). Statewide, nearly 22,000 miles of streams have been lost due to channelization (Funk and Ruhr 1971). As a result of the erosion and water velocity that follows channelization, more sediment is carried downstream, causing changes that stress plant and animal communities.

Reduced biodiversity

Loss of native species and the rapid spread of exotic species that replace native species threaten the health of many Minnesota rivers. Nearly 50 Minnesota aquatic species are endangered, threatened, or of special concern (MDNR 1989). Many, including Higgin’s eye and fat 10

pocketbook mussels, lake sturgeon, paddlefish, snapping turtle, bullfrog, osprey, and bald eagle, are dependent on rivers for some part of their life cycle. Many exotic species, including zebra mussels, sea lamprey, ruffe, purple loosestrife, and Eurasian watermilfoil, are nuisances in Minnesota rivers. Others, however, like brown and steelhead trout, are highly valued. Changes in native communities (the loss of species and the introduction of exotic species) alter nutrient cycling and the productivity of rivers and interconnected ecosystems (Winter and Hughes 1997).

The number of at-risk species, fish community composition, the amount of fish habitat, and the presence of streambank vegetative cover are measures of river health.

EXISTING POLICIES AND PROGRAMS

Several federal laws provide a solid basis for maintenance and restoration of river and stream health. The conservation provisions of the 1996 Farm Bill address high-priority goals for river and stream protection and water quality. The Conservation Reserve Program (CRP) reduces erosion and sediment delivery to rivers by encouraging the planting of permanent vegetation on highly erodible agricultural lands. The Conservation Reserve Enhancement Program in Minnesota augments CRP efforts and specifically targets land adjacent to the Minnesota River. The program seeks permanent conservation easements and reestablishment of native vegetation to reduce nonpoint-source pollution in the basin. The Environmental Quality Incentives Program establishes conservation priority areas where significant river pollution problems exist and provides technical and financial assistance for conservation practices such as manure management systems and erosion control. The Wetland Reserve Program and the Wetland Conservation (Swampbuster) Program help improve river water quality by protecting wetlands that act as filters. The federal Water Pollution Control Act (the Clean Water Act) mandates comprehensive programs for eliminating or reducing the pollution of interstate waters and tributaries and improving the sanitary conditions of surface and underground waters. The act gave the EPA authority to set water11

quality standards and regulate discharge of pollutants into surface waters and provided funding for sewage treatment faciltities. The Endangered Species Act of 1973 provides for the conservation of ecosystems on which threatened and endangered species of fish, wildlife, and plants depend, both through federal action and by encouraging the establishment of state programs. Other federal acts that help protect and maintain rivers and streams include the Nuisance Control and Prevention Act, Wild and Scenic Rivers Act (1968), Federal Aid in Sport Fish Restoration Act (1950), Federal Power Act (1920), and the Rivers and Harbors Appropriation Act of 1899. In Minnesota, the DNR shares responsibility for managing rivers and streams and adjacent shorelands with the Board of Water and Soil Resources and the U.S. Army Corps of Engineers. The MDNR Shoreland Management program encourages development of shorelands in ways that enhance water quality and preserve scenic resources. The Floodplain Management program restricts development in floodplains to minimize the threat to life and property resulting from flooding and to preserve the water-holding capacity of floodplains. The Wild & Scenic Rivers program preserves rivers with outstanding scenic, recreational, natural, historical, and scientific values from overdevelopment and recreational overuse. The DNR Water Permits Program regulates changes in the

beds of rivers and streams that alter the course or cross-section. Innovative, multi-stakeholder parterships are bringing citizens and resource professionals together to gain understanding of aquatic ecosystems and develop innovative ways to manage them sustainably. Examples include the Tri-County Leech Lake Watershed Project in north-central Minnesota and the Upper Mississippi River Basin Association (MN DNR 1997). The Clean Water Partnership Program administered by the MPCA provides local governments with financial and technical assistance for watershed projects that protect and improve rivers and streams. Additional programs (and their sponsors) that assist individuals and local units of government to maintain and improve river quality include Agricultural Best Management Technical Assistance (BWSR), Flood Damage Reduction (DNR), Hydrologic Unit Areas Program (USDA, NRCS, Minnesota Experiment Station), River Friendly Farmer (MES, MPCA, NRCS, and Soil and Water Conservation Districts), Water Quality Incentive Program (NRCS), and Watershed Program (PL-566; MRCS).

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EXAMPLE INDICATORS

Table 1 collects the indicators used in this chapter. The indicators are organized within the EII framework, which helps illustrate relationships among human activities,

environmental condition, the flow of benefits, and strategies for sustaining a healthy environment. The indicators used in this chapter are examples that illustrate how indicators may help assess the health of rivers and streams. The process of developing a comprehensive set of indicators that

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assess river and stream health and inform environmental decision making is ongoing. Developing indicators will require collaboration with stakeholders interested in their use, testing, refinement, and standardization of measurement techniques.

REFERENCES Aadland, L. 1997. Dams, ditches, and the Red River ecosystem. Minnesota Chapter of the American Fisheries Society Newsletter 1:7. Cannon River Watershed Partnership. 1996. Cannon River Watershed Plan: Executive summary. Cannon River Watershed Partnership, Faribault, Minn. Environment Canada. 1991. A report on Canada’s progress towards a national set of environmental indicators. Environment Canada, Ottawa. Funk, J. L., and C. E. Ruhr. 1971. Stream channelization in the Midwest. Pages 5-11 in Schneberger and Funk, eds., Stream channelization: A symposium. American Fisheries Society Special Publication no. 2. Minnesota Department of Health (MDH). 1996. Minnesota fish consumption advisory. Minnesota Department of Health, St. Paul. Minnesota Department of Natural Resources (MDNR). 1988. Statewide instream flow assessment. Technical report, Div. of Waters, Minnesota Department of Natural Resources, St. Paul. _____. 1989. The drought of 1988. Div. of Waters, Minnesota Department of Natural Resources, St. Paul. _____. 1995. Water year and data summary: 1993 and 1994. Div. of

Waters, Minnesota Department of Natural Resources, St. Paul. Minnesota Environmental Quality Board. 1988. Minnesota’s environmental quality: Trends in resource conditions and current issues. Minnesota Environmental Quality Board, St. Paul. Minnesota Planning. 1996. Minnesota milestones: 1996 progress report. Minnesota Planning, St. Paul. Minnesota Pollution Control Agency (MPCA). 1993. Preserving Minnesota’s environment for 25 years. Minnesota Pollution Control Agency, St. Paul. _____. 1994. Minnesota river assessment project report: Executive summary. Minnesota Pollution Control Agency, St. Paul. _____. 1995. Tracking our progress in protecting Minnesota’s environment. Minnesota Pollution Control Agency, St. Paul. Pajak, P., et al. 1994. Agricultural land use and reauthorization of the 1990 Farm Bill. Fisheries 12 (19): 2227. Paragamian, V. L. 1990. Fish populations of Iowa rivers and streams. Technical bulletin no. 3. Iowa Department of Natural Resources, Des Moines. Pfannmuller, L. A., and B. A. Coffin. 1989. The uncommon ones: Minnesota’s endangered plants and animals. Minnesota Department of Natural Resources, St. Paul.

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Tester, J. R. 1995. Minnesota’s natural heritage: An ecological perspective. University of Minnesota Press, Minneapolis. Upper Mississippi River Conservation Committee (UMRCC). 1993. Facing the threat: An ecosystem management strategy for the Upper Mississippi River. Upper Mississippi River Conservation Committee, Rock Island, Ill. U.S. Environmental Protection Agency. 1990. Environmental monitoring and assessment program: Ecological indicators. EPA/600/390/060, Office of Research and Development, Washington, D.C. _____. 1996. Environmental indicators of water quality in the United States: Fact sheets. EPA 841F-96-001, Office of Water, Washington, D.C. U.S. Fish and Wildlife Service. 1997. 1996 national survey of fishing, hunting, and wildife-associated recreation, state overview. U.S. Dept. of the Interior, U.S. Fish and Wildlife Service, August 1997. Vannote, R. L., G. W. Minshall, K. W. Cummins, J. R. Sedell, and C. E. Cushing. 1980. The river continuum concept. Canadian Journal of Fisheries and Aquatic Sciences 37:130-37. Ward, J. V., and J. A. Stanford, eds. 1979. Ecology of regulated rivers. Plenum Press, New York. Winter, B. D., and R. M. Hughes. 1997. Biodiversity. Fisheries 22 (1): 22-29.