Strategies for Watershed Protection in Urban Areas
- Stop developing in floodways. Instead use these areas as greenways.
- Collaborate with agricultural interests, through watershed management authorities, to develop watershed management plans that benefit stakeholders throughout the watershed and reduce downstream flood potential.
- Require buffers along streams and utilize natural drainage ways as green infrastructure.
- Utilize constructed wetlands and retention ponds for flood control in areas of new development.
- Promote the use of rainscaping strategies to protect water quality and reduce runoff. Manage smaller rains through infiltration based practices, including protection and restoration of soil quality, bioretention, permeable pavement, native landscaping, and rainwater harvesting.
Education and Outreach
- Expand educational efforts to help people understand their hydrologic footprint and ways they can contribute to water quality protections. For instance:
- Prevent pollution from oil and grease by keeping vehicles in good working order.
- Don’t dump or discharge pollutants into storm sewers or leave grass clippings on the landscape.
- Use phosphorous-free fertilizers.
- Support state and federal funding for conservation programs that provide financial assistance for the adoption of practices that hold more water in the uplands.
- Create 28E agreements that help fund the installation of practices in watersheds above cities that provide downstream flood protection and improve water quality.
- Create stormwater utilities and utilize part of the revenue stream for local cost-share programs that help reduce flooding and protect water quality.
- Encourage the use of the State Revolving Loan program for stormwater management practices.
Stormwater Practices for your community
Soil Quality Restoration- The process of improving soil health on new or existing lawns. The process uses tillage, aeration, and compost to increase infiltration and organic matter content. Soil quality restoration leads to healthier soils that can absorb more rain.
Native Landscaping- Native plants should be strategically placed in the landscape to enhance infiltration of stormwater. Their extensive root systems hold soil, slow runoff, and improve infiltration. The plants also absorb nutrients, such as nitrogen and phosphorous, and don’t require fertilizer, pesticides, or supplemental water to survive after establishment.
Rain Gardens, Bioretention Cells & Bioswales- Engineered vegetate landscape features built to capture runoff from impervious surfaces and filter pollutants from runoff. They treat small storms, while runoff from lager storms flow to storm sewers or larger regional conservation practices
Detention and Retention Basins- These are sized to store and slowly release stormwater to alleviate downstream flooding. They can also be designed to manage small storm events to improve water quality, reduce streambank erosion, and provide flood control.
Permeable Pavers- This pavement system us used in place of traditional concrete or asphalt to decrease stormwater runoff. Unlike traditional surfaces, permeable pavers allow stormwater to seep through the joints in the pavers and enter the spaces in the gravel below. Water then moves into the soil or slowly into a stormwater drain.
Constructed Wetlands- Used both for water quality and flood management, constructed wetlands provide a permanent pool of water which varies in depth. The collection area provides temporary storage, removal of pollutants, and habitat for wetland plants and wildlife.
Long-term inspection and preventative maintenance is critical to ensure performance and aesthetics of stormwater practices. Project plans should include short and long-term maintenance schedules. Additionally, property owners should be educated about primary inspection points, such as inlets, outlets, overflows, vegetation, and side slopes.
Strategies for Watershed Protection on Agricultural Lands
- Work with cities, through watershed management authorities, to develop watershed management plans that benefit stakeholders throughout the watershed and reduce downstream flood potential.
- Use no-till farming to improve soil quality and increase the landscapes ability to absorb more rain.
- Install contour buffer strips to help absorb runoff.
- Retire highly erodible land with low profitability through the Conservation Reserve Program. Reconstruct prairie areas to improve soil quality.
- Construct ponds and wetlands that hold and slowly release water to reduce downstream peak flows.
- Promote federal and state cost-share programs to comprehensively install conservation systems on critical lands throughout the watershed.
- Encourage the use of low-interest loans through the State Revolving Fund to install conservation practices on agricultural land.
Nutrient Reducing Practices- Conservation practices that reduce the amount of nutrients such as nitrogen and phosphorus that enter surface waters. Bioreactors and saturated buffers are used to remove nitrates from underground tile water before it enters a nearby stream or pond. Strips of perennial vegetation (filter strips) are placed along water sources to intercept surface water runoff, removing excess nutrients.
In Field Practices- Permanent structural practices or management changes that are done within the boundaries of an agricultural field. The structural practices, like terraces and basins, are used to control water runoff and reduce erosion. Cover crops and reduced tillage are management changes that can also reduce runoff while improving soil health and water quality.
Upstream Retention Structures- Pond and wetlands are strategically placed in the upper portion of the watershed to hold back and slow down water movement. This decreases how fast the water moves to downstream communities, reducing the flood risk. Along with these water quantity benefits, these structures can also improve water quality and create essential wildlife habitat.
Land Retirement (CRP)- This process involves taking unprofitable and highly erodible farm ground out of production. Once out of production the land is planted to a perennial species, usually native prairie. These areas provide wildlife habitat, prevent erosion, and improve soil health leading to less surface run off.
Watershed Management Authorities
In 2010, Iowa lawmakers passed legislation authorizing the creation of Watershed Management Authorities (WMA). A WMA is a mechanism for cities, counties, Soil & Water Conservation Districts, and stakeholders to cooperatively engage in watershed planning and management. Four WMAs have formed in the Des Moines metro area- Fourmile Creek, Mud/Camp/Spring Creeks, Walnut Creek, and Beaver Creek.
Many communities have seen the value of working together to develop watershed management plans and unifying policies that will improve and protect water quality in the region. During the planning process, high priority goals were set utilizing public and stakeholder input. Specific strategies are found throughout the plans to show what steps the urban and rural stakeholders can take to reach these goals. Strategies range from policy and ordinance changes to conservation practices. Watershed scale planning efforts have also shown communities the benefit of working with farmers to make improvements on the agricultural lands.
Watershed plans have been complete for three of the metro WMAs (Fourmile, Walnut, Mud/Camp/Spring Creeks). With plans complete WMA boards are proceeding to implement their plans. To achieve the lengthy list of goals, the jurisdictions within each of these WMAs pooled their resources to hire a watershed coordinator. The jurisdictions chose to have the Polk Soil & Water Conservation District move forward with WMA coordination. Polk SWCD provided leadership during the formation and throughout the watershed management planning process with the aid of Urban Conservationist, Jennifer Welch. Now Polk SWCD staff are working one on one with cities, farmers, partners, and others to implement the watershed management plans and improve water quality.
Green Infrastructure and Greenways (link to another page)
To protect water quality and quality of life, communities must also protect green infrastructure- the interconnected network of open space and other natural areas. Green infrastructure is an integrated landscape approach and a conservation strategy that recognizes the interactions between the built environment, rural lands, and native ecosystems.
Communities can retain an interconnected network of waterways, wetlands, prairies, woodlands, wildlife habitats, and natural areas. If not protected during development, these areas and their functions are lost. Protecting green infrastructure provides a “treatment train” that reduces the volume of runoff generated and can be used to protect water quality.
Without green infrastructure and design techniques to manage runoff differently, the storm water moves rapidly to storm sewers and into streams and rivers without any treatment, increasing flooding and reducing water quality. This often results in the use of costly engineering solutions for problems that can be avoided or mitigated by protecting intact natural resources, so they do not lose their natural function. If protected, as water moves through a treatment train outlined in the natural resources inventory, it is filtered through infiltration, and peak flows are reduced and delayed. A major component of the natural resources overlay district will be to lay the groundwork for future adoption of green infrastructure methods. A developed plan outlining valued resources is a vital step towards future protection from development.
Incorporating Community Priorities
Often communities have a common goal to improve quality of life for their residents. Connecting natural resources to this can help fully achieve benefits for residents and the environment by focusing on several key principles.
The principle for a safe community, where the effects of urban development are mitigated to protect downstream properties from negative impacts such as flooding, pollution or other impairments.
The principle to promote active lifestyles where a system of open spaces interconnected by trails for walking, jogging and biking. These systems could also provide access and public education opportunities around wetlands, streams and other vital habitats.
The principle for an environmentally sensitive and sustainable city featuring clean surface water and flow control. Developments, facilities and infrastructure are planned to be more environmentally conscious. A network of connected green spaces is provided throughout communities. Effective regional rainwater management is employed. Existing vital environmental areas and open spaces are located and preserved.
Sometimes green infrastructure is protected through other mechanisms, such as greenway development.
Definition of a greenway:
a linear corridor of open space along a waterway, promoting public health, safety and general welfare thru flood protection and water quality improvements. Greenways are intended to be land protected for environmentally sustainable purposes and may include passive recreation and educational amenities, cultural resources, urban agriculture, conservation, and non-vehicular transportation.