Human Impacts

Iowa’s rivers, lakes, streams, and wetlands are important for a host of reasons. Learn about how we depend on and interact with aquatic resources, both positively and negatively.

Iowa-Relevant Aquatic WILD Activities

Activities with supplemental information are linked below.

Alice in Waterland
(3-5, 6-8)
Aquatic Roots
(6-8, 9-12)
Aquatic Times
(3-5, 6-8, 9-12)
Blue Ribbon Niche
(3-5, 6-8)
Designing a Habitat
3-5, 6-8)
Dragonfly Pond
(3-5, 6-8)
Migration Headache
Plastic Voyages
Riparian Retreat
Something’s Fishy Here!
The Glass Menagerie
To Dam or Not to Dam
Water Canaries
(6-8, 9-12)
Water We Eating?
Water Wings
(3-5, 6-8)
Wetland Metaphors
What’s in the Air?
What’s in the Water?
Where Does Water Run?
(6-8, 9-12)

Supplemental Resources

Water Supply

Millions of residents rely on water from impoundments and rivers for public use, industrial supplies, power plant cooling, and wastewater treatment. In Iowa, surface water supplies about 20 percent of the state’s drinking water.


Iowa’s aquatic resources are important to many of the outdoor activities we enjoy. Two of the most popular outdoor recreational activities are swimming and fishing. Boating, waterfowl hunting, and a host of other recreational pursuits also are dependent on our waters.

Pollution and Flood Control

Wet soils of riparian areas and other wetlands help maintain and improve water quality in streams, rivers, and lakes. Water quality is greatly impacted by land use practices. Runoff carrying potential pollutants such as silt, fertilizer, and animal waste, can be absorbed and used by aquatic plants before it enters the water system. Pollutants may be retained by wet soils long enough for bacteria to break them down into harmless compounds. Wet soils store excess water, releasing it slowly over time into streams, lakes, and groundwater to prevent downstream flooding.

  • EPA: Why are Wetlands ImportantWetlands provide numerous benefits for people, fish, and wildlife including flood protection and filtering pollutants.


The Missouri and Mississippi, like most large rivers in the U.S, are major modes of transportation. The Mississippi is very important to commercial navigation.

Commercial Harvest

Commercial fishing in Iowa is done almost exclusively on the Mississippi. A few other products harvested from aquatic habitats and associated riparian or wetland areas include timber (e.g., oaks, black walnut, cottonwood); nuts (e.g., walnut, hazelnut); and even wild rice from the backwaters of the Mississippi.

Electrical Generation

The dam at Keokuk is currently the only one on an Iowa river used to generate electricity, but dams in the upper reaches of the Missouri (upstream from Iowa) are used for this purpose. In 2016, construction continues on a hydroelectric generation plant at the dam on Lake Red Rock, on the Des Moines River. The Cordova nuclear power plant upstream from the Quad Cities, uses river water for cooling. The electricity generated is used by many homes, businesses, and industries.


Aquatic ecosystems are among the most diverse in the world. The Mississippi River corridor is home to a wide array of fish and wildlife species and is a migration corridor for 40 percent of North America’s waterfowl and shorebirds. Many species of waterfowl, amphibians, and other wildlife depend on wetlands for food, shelter, and to raise their young. In the United States, 190 amphibian species, 5,000 plant species, and one-third of all native bird species depend on aquatic habitats. In Iowa, approximately 700 plant and animal species use aquatic habitats. Water sources also are essential for terrestrial animals.

  • Iowa’s Nature Series – VertebratesFrom city sewers to pristine prairies, the reptiles, amphibians, birds, mammals, fish, and lamprey found within Iowa’s borders are as diverse and fascinating as the people found there.
  • Iowa’s Nature Series – InvertebratesFeatures the stories of a few of the thousands of insects, spiders, crustaceans, butterflies, moths, worms, snails, mussels, and leeches found in Iowa, everywhere from our border rivers to our homes.


People always have been closely associated with water sources for drinking, food, and transportation. Iowa waters are no exception. Portions of the Upper Mississippi River are thought to have the highest density of cultural sites in North America–a study by the Great River Environmental Action Team identified over 1,000 anthropological and nearly 4,000 historic sites in the Rock Island District. The Missouri was used by the Dakota, Iowa, Oto, Winnebago, Fox, and Pottawatomie Indian tribes as well as early Euro-American explorers. The natural lakes of northwest Iowa also were centers of cultural activity for native and prehistoric Americans.

Issues Facing Our Aquatic Resources

Water quality in all surface waters has been affected greatly by alterations in the landscape–largely brought about by agriculture. Changes to land draining to lakes and streams (watersheds) often occur far from the affected body of water, thus cause and effects are not readily apparent. Nonpoint pollution is the greatest factor impacting the quality of Iowa’s waters.

Erosion and Sedimentation

The number one water pollutant in Iowa is silt (very fine soil). Soil is carried to bodies of water by surface runoff, wind, or stream bank erosion.

Fertilizers (nitrogen)

Manufactured fertilizers containing nitrogen and phosphorous are used for crop production. Nitrogen is by far the most prevalent nutrient and most recognized contaminant in Iowa’s groundwater.

Animal Waste

Besides acting as nutrients, large amounts of animal wastes entering a body of water can be toxic to fish and other aquatic animals. Over 1 million fish died in kills caused by manure discharge between 1997 and 2001 in Iowa. Fish kills have increased dramatically in the past few years.


Pesticides (herbicides, insecticides, etc.) are an important part of Iowa’s agriculture but heavy use can negatively impact aquatic ecosystems. The greatest threat to aquatic systems is from aerial applications because of overspray and drift.

Destruction of Habitat

Iowa has lost much of its original habitats. Within 100 years of Euro-American settlement, ninety-five percent of Iowa’s wetlands were drained or filled. Seventy percent of the forests were cleared, and more than ninety-nine percent of the prairies were plowed. Soils were exposed and natural vegetation along rivers and streams was removed. The result was a drastic increase in erosion in the watershed and sediments entering our waters.


Historically, the Prairie Pothole Region provided an important stopover site for over thirty species of shorebirds that arrive to eat aquatic life in shallow ponds, temporarily flooded by spring runoff. To date, the Prairie Pothole Region has lost about 50 percent of its wetlands, with some areas having lost as much as 90 percent. Iowa has lost 98 percent of its prairie potholes. Related to this loss is the decline in shorebird populations over the last two decades; a decline of 60-80 percent in some species. Without adequate food at their stopover sites the birds cannot reach the breeding grounds to reproduce. Wetlands (including near shore areas in lakes and river backwaters) also are important nurseries for fish.

Riparian Zones

Loss of riparian zones has impacted Iowa streams and rivers. Urban development, highways, cropland, etc., are squeezing wildlife into smaller areas. Sections of rivers that are bare, unshaded, sediment-laden channels are poor habitat for fish and other aquatic organisms. Areas void of a vegetative zone provide insufficient cover and food for upland game, songbirds, and other wildlife, especially in winter.

Lakes, Rivers, and Streams

When large amounts of sediment are deposited in a lake, stream, or river, it is called sedimentation. The result of erosion and deposition of Iowa’s valuable topsoil into lakes and streams is very damaging. Sedimentation reduces the depth of lakes and streams. Deposited soils cover valuable habitat and choke out many essential parts of the ecosystem. They kill aquatic plants because sunlight cannot reach them and reduce fish habitat by filling holes and crevices where fish seek shelter. Excessive amounts of sediment in rivers cover rock and gravel substrates so invertebrates can’t cling to the rocks, eliminating food for fish. In both lakes and rivers, sedimentation smothers fish spawning sites for species like walleye and trout.


Dams have cut the Mississippi River into sections, creating a series of deep pools preventing the migration of fish. Unable to ascend the river to spawn, the skipjack herring has all but disappeared from the river above Keokuk, Iowa. The ebony shell, once the upper Mississippi’s dominant mussel, has nearly disappeared because the larval form needs a ride on the gills of the skipjack herring to complete its life cycle. Navigation dams also worsen sedimentation problems.

Introduction of Exotic Species

Organisms introduced into habitats where they are not native are exotic species. Although their impacts are not nearly as profound in Iowa as in more southern areas of the United States, a few species have had impacts worthy of note.

Improving Our Aquatic Resources

People can have positive impacts on aquatic resources. Following are some ways human actions are helping to protect or enhance aquatic ecosystems:

Watershed Improvements

Funds through the U.S. EPA Clean Lakes Program combined with local grants and private donations have funded water quality projects to improve, protect, and restore water bodies and watersheds. Practices being used include terracing, grass waterways, contouring, strip cropping, rotational grazing, and minimum tilling.

Fisheries Management and Research

Fisheries management personnel work with all stakeholders to help assure the quality of Iowa’s aquatic resources aren’t compromised. Six fisheries research teams are involved in over 20 long term projects designed to solve major problems impacting Iowa’s aquatic resources.


Iowa DNR biologists and other agency personnel monitor our resources to assess long term changes in fish and wildlife populations from changes in habitat. Monitoring also is used to assess how management activities benefit resources where they are applied.

Long Term Monitoring

The Long Term Resource Monitoring Program (LTRMP) on the Mississippi River was authorized by Congress and initiated in 1987. It was designed to address resource problems such as navigation impacts, sedimentation, water level fluctuations and quality, lack of aquatic vegetation, and reduced fish populations in addition to monitoring invertebrate populations and land cover / use.

Wetlands are monitored through the National Wetlands Inventory which began in 1974. This project was established through the Emergency Wetlands Resources Act, which directed the FWS to generate information about the characteristics, extent, and status of the nation’s wetlands. These maps are sold through the USGS (1-800-USA-MAPS).

Monitoring Safety of Fish for Consumption

Fish tissue monitoring is conducted in Iowa by the DNR as part of the Environmental Protection Agency (EPA) Regional Ambient Fish Tissue Program (RAFT). Some contaminants not in use anymore still persist in the environment, but levels are decreasing each year.

Water Quality

Monitoring water quality can provide information about how to sustain or improve aquatic ecosystems. Fisheries biologists also collect water quality data because these indicate whether or not fish (and other animals) can live in a body of water.


Volunteers can be instrumental in monitoring aquatic resources. Several Iowa DNR Wildlife Diversity Program surveys are conducted largely by volunteers. Individuals wanting to go beyond monitoring can get involved in the DNR’s Adopt-a-Program. Individuals or groups can adopt a body of water, park, or other natural area and monitor, maintain, or improve it!

General Conservation Practices

General conservation practices improve our resources. Waste of materials which require water for their manufacture or waste of water processed for drinking, increases demands put on our lakes and rivers both when water is drawn from the source, and when waste water is processed and added to a system.

Federal Regulations and Programs

The Sport Fish Restoration Fund was established to provide funding for the maintenance and improvement of the nation’s fisheries resources.

The Clean Water Act is the primary federal law, enacted in 1972, that protects our nation’s waters, including lakes, rivers, aquifers, and coastal areas. Its primary objective is to restore and maintain the integrity of the nation’s waters. Its goals are to eliminate the discharge of pollutants and achieve water quality levels safe for fishing and swimming.

Left out of the Clean Water Act were many activities that affect waters through agricultural production. The 1985 Farm Bill helped fill this gap by providing two federal programs–the Swampbuster Provision and Conservation Reserve Program (CRP). Both of these programs have helped reduce silt in Iowa rivers and streams by reducing erosion from farm land.

The Conservation Reserve Program (CRP) is a voluntary effort that allows producers to retire highly erodible land from annual production for 10 years (or more in some instances) either via competitive bid during specific periods or can be enrolled at any time under continuous signup efforts that target specified environmental goals. In return, producers get annual rental payments and cost-share and technical assistance to install approved conservation practices on those acres. However, the program is nearing the legislated maximum limit of acres allowed in the program.

The Wetland Reserve Enhancement Partnership (WREP) is a voluntary program through which NRCS enters into agreements with eligible partners to leverage resources to carry out high priority wetland protection, restoration, and enhancement and to improve wildlife habitat.

A wetland easement is a perpetual agreement by a landowner and the U.S. Fish and Wildlife Service (USFWS). The Iowa DNR assists the USFWS with this program. The landowner receives a single lump sum payment not to drain, burn, level, or fill wetlands covered by the easement.

The Prairie Pothole Joint Venture (PPJV) is a cooperative effort between state, federal, and county agencies and conservation organizations. The goal in Iowa is to raise two million dollars each year to protect 2,700 acres of wetlands and surrounding uplands through acquisition and easements.

The Partners for Wildlife Program (PWP) improves and protects wildlife habitat on private lands through alliances between the FWS, IDNR, and other organizations and individuals, while leaving the land in private ownership.

North American Wetlands Conservation Act Grant applications are submitted through the North American Wetlands Council for projects which: 1) protect, enhance, restore, and manage an appropriate distribution and diversity of wetland ecosystems and other habitats for migratory birds and other fish and wildlife; 2) maintain or improve migratory bird populations distributions; or 3) sustain an abundance of waterfowl and other migratory birds consistent with the international migratory bird treaties and agreements.

The purpose of the Service Challenge Cost-Share Program (SCCSP) is to increase awareness and participation of local communities for conservation of important fish, plant, and wildlife resources on private and public lands. It also enhances public lands and their use, maintains USFWS lands, and is used for research.

State Legislation and Programs

A fishing license is required for Iowans 16 years of age and older and non- residents who are at least 14 who fish on land other than their own. Funds from fishing licenses are directed at efforts to maintain and improve the quality of Iowa’s sport fishing. Activities of the Fisheries Bureau of the DNR include lake construction and management, habitat restoration projects, fish stocking, research, and public education.

The Groundwater Protection Act was adopted by the Iowa legislature in 1987, and focused on reducing potential contamination from industrial and agricultural chemicals and preserving drinking water quality.

Resource Enhancement and Protection (REAP) was enacted in Iowa in 1989, to enhance and protect Iowa’s natural environment. Funding is allocated for conservation education, land acquisition, soil and water conservation, park development, and other environmental projects.

Private Programs

The Izaak Walton League is a non-profit conservation organization that works to protect America’s soil, woods, waters, and wildlife. The League heads the Save Our Streams

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