Des Moines and Raccoon River Watershed
DES MOINES AND RACCOON RIVER WATERSHED FACTS
Everyone lives in a watershed. A watershed is the area of land that catches rain and snow and drains or seeps into a marsh, stream, river, lake or groundwater. Des Moines residents receive their water from the Des Moines and Raccoon River watersheds.
Raccoon River Facts
- 23 counties contiguous to the watershed
- contains 28 rivers and streams
- 3595.5 total river miles
- contains 301 lakes - 9731.5 total acres
- covers 3639.25 square miles of land
- 519.99 perimeter miles
Des Moines River Facts
- 26 counties contiguous to the watershed
- contains 47 rivers and streams
- 3973.4 total river miles
- contains 255 lakes - 20,601.4 total acres
- covers 5020.4 square miles of land
- 948.74 perimeter miles
Maps
What is a watershed?
Why is a watershed important?
Do watersheds affect drinking water quality?
What is the difference between “point” and “non-point” sources of pollutants?
What features make a watershed unique?
How are watershed “addresses” determined?
How can I be “watershed friendly?
How can I reduce or eliminate non-point source pollutants?
A watershed is an area of land that drains into a river, lake, stream, pond, or other body of water. It includes the waterway itself and the entire land area that drains into it. For example, the watershed of a lake includes any streams emptying into the lake and the land area that drains into those streams. A watershed can be small, like a backyard puddle, or large, such as Lake Michigan.
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We all live in a watershed and we all rely on this water and other natural resources to exist. The type of land use – agricultural, suburban, urban – and its associated activities have a direct impact on the water quality of the watershed. When it rains or when snow melts, the water runs downhill into the watershed, carrying the effects of human activities into the watershed. What you and others do on the land impacts the quality and quantity of our water. A healthy watershed is necessary for a healthy environment and economy. Our watershed provides the community with water for drinking, irrigation, industry, and recreation. Wildlife also depend on a healthy watershed for their food and shelter. We are all responsible for preserving and protecting our watersheds.
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Your watershed area is a unique and dynamic place and the area nearest the water greatly affects drinking water quality. Water conservation and preservation not only improve water quality, but also save money by reducing the pumping and treatment costs. They may also extend the life of our water treatment facilities and are far less costly than developing a new water supply.
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Point source pollutants come from specific places that we can identify and control. Examples of point source pollutants include sewage treatment plants, industries, hog lots, and storm sewers. Much progress has been made in preventing water quality problems from point source pollutants. Non-point sources come from many different areas as water runs off or moves through the ground. They result from a wide variety of human activities in the watershed. The severity of this type of pollution is proportional to the state’s population density and distribution, the intensity of local agricultural activities, and other land uses. Some examples include forestland runoff, failing septic systems, parking lots, construction sites, and automobile exhaust. Non-point source pollutants are difficult to identify, measure, isolate and control. Non-point source pollution generates over 50% of all water pollution. It is best controlled through voluntary efforts.
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Some watersheds are large and may include many smaller watersheds, such as the Des Moines and Raccoon Rivers . Others are small, like a puddle in your backyard.
Boundary: The geographical boundary of your watershed is formed by a ridge or high area from which water either drains towards or away from your watershed.
Terrain: How flat or how steep (terrain) the land is impacts how fast the water drains. The faster the drainage, the greater for potential flooding and increased soil erosion.
Soil Type: Sandy soil allows the ground to soak up water faster, reducing runoff. Clay soils do not allow as much water infiltration, leading to greater runoff.
Land Use: The area nearest the water can impact the watershed. Is it a filter / buffer strip? Wildlife habitat? Wetlands? Industry? Agriculture? Urban or suburban? All of these add unique features to a watershed.
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Watersheds in the United States have a name as well as a corresponding 2 – 16 digit number assigned to them, providing a distinct “watershed address” for a location within a system of hydrologic units. The more digits assigned to a watershed, the smaller its size.
If you would like more information on watershed addresses, visit the Know Your Watershed website at: http://www.ctic.purdue.edu
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Know where water goes when it leaves your property.
Collect and recycle used motor oil. Each year as much as 132 million gallons of used motor oil is poured down storm sewers or sent to landfills.
Recycle newspapers, glass, plastic, and metal. Don’t let these pollute your watershed.
Take a soil test before determining the fertilizer mixture and application rate your lawn requires.
Wash your car on the lawn to filter pollutants and reuse water.
Know whether your home is hooked to a septic tank or municipal sewer system. If you have a septic system, have it checked periodically.
Know the source of your drinking water and help protect the water sources.
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Water: A Story of Hope, a report of the National Forum on Nonpoint Source Pollution, offers these tips:
Clean up after your pets to avoid runoff of nutrients and disease-causing microorganisms.
Never pour toxic household chemicals down the drain, sewer, or on the ground. Take them to a hazardous waste collection center.
Recycle used oil and antifreeze by taking them to service stations and other recycling centers.
Schedule regular tune-ups for your car to reduce deposition of toxic pollutants and petroleum by-products from exhaust gases.
Have your septic system inspected and maintained regularly.
Landscape with native plants. They require less water, fertilizer, and pesticides.
Select porous materials such as gravel for walkways and driveways to increase filtration and decrease surface runoff.
If you live by a shore, contour your lawn to reduce runoff into the water.
Spread mulch on bare ground and plant bare patches to prevent erosion and runoff.
Test your soil before applying fertilizers to achieve proper application levels and minimize nutrients leaching into groundwater or running off into surface waters.
Keep fertilizers off paved areas, including driveways and sidewalks, to prevent rain from washing the nutrients into the street and storm drains.
If you use a professional lawn care service, select a company that follows practices designed to apply fertilizers and pesticides sparingly and properly.
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Source Water Assessment Program
Des Moines Water Works’ (DMWW) Source Water Assessment project allowed us to increase efforts to protect water resources at the local level by encouraging and involving key people within the communities. This project also fulfilled the requirements of the Safe Drinking Water Act (SDWA) Amendments of 1996 for state source water delineation and assessment.
The first three components of the program included delineation, contaminant inventory, and susceptibility analysis. Delineation consisted of determining the boundaries for the watersheds draining into the water source of each utility. For DMWW, watershed delineations above the intake structures for both the Raccoon and Des Moines Rivers were ascertained. Contaminant inventory consisted of identifying possible sources of contamination located within the watersheds, while the susceptibility analysis determined which of the possible sources of contamination are most likely to pollute our water sources and reach the intake structures. By preventing contamination, we will be better able to treat the water, providing a better quality water, and saving treatment costs.
Delineation
Delineation identified the topographic area of the entire watershed upstream of the public water supply’s intake structure. It is the area of land that catches rain and snow and drains into a stream, river, lake, or groundwater forming our source water.
Watersheds in the U.S. are designated with a name and corresponding 2-16 digit number, providing a “watershed address” within a system of hydrologic units. The larger the hydrologic unit number, the smaller the size of the watershed. In our project, we used the 11-digit hydrologic unit, which divides the larger watershed up into smaller subwatersheds ranging in size from 40,000-250,000 acres.
Des Moines Water Works has two sources of source water, the Raccoon and Des Moines Rivers , so there are two major watershed areas delineated. In the map below, the Raccoon River appears in green and the Des Moines River appears in purple. As you can see, part of the Des Moines River watershed extends into Minnesota.
Contaminant Inventory
Contamination can come from a variety of sources. One type is point sources- sources that can be pinpointed to one location, such as animal feed lots, gas stations, or factories. These are considered potential sources of contamination because they can release contaminants into the watershed, and eventually the source water. Another type is non-point sources- sources not specific to one location. These types of sources may include land run-off and erosion.
Susceptibility Analysis
Susceptibility analyses were completed as part of the Source Water Assessment project. These analyses made susceptibility determinations based on the potential for Des Moines Water Works to draw water contaminated by inventoried potential sources at concentrations that would cause concern. These determinations took into consideration any long-term impact that contaminants from inventoried potential sources may have on our source water. In addition, the watersheds that were most closely analyzed included areas having a 72-hour time of travel upstream from our intake structures and that were located within 1320 feet of a waterway.