Using Nature to Mitigate Stormwater

Using Nature to Mitigate Stormwater

Why are we placing all of this attention on stormwater runoff?

Because it has become the largest source of pollution entering our rivers and streams.

Front lawn replaced with native plants to reduce stormwater runoff.
Front lawn replaced with native plants to reduce stormwater runoff.

Shorewood is an attractive suburb just north of the city of Milwaukee, bordered by Lake Michigan on the east and the Milwaukee River on the west.  Water plays an important role in the culture of Shorewood.  The 4th of July celebration is atop a bluff overlooking the lake; two beer gardens lie along the river, sport fly fishing is popular in the river, and surfing is common off the shores of the beach.  Community parks line the river and the lake.

Shorewood and communities to the north are facing the same challenge – how to keep rivers and the lake clean and healthy, or in the words of the Clean Water Act, “fishable and swimmable”?  How do communities respond to the increased frequency and intensity of storms and the problem of stormwater runoff, and still maintain the character of the communities?

Big detention ponds, concrete channeled streams and larger municipal pipes are one possible solution, but they’re expensive and there’s no space for these large detention ponds.

Fortunately, there are new solutions that not only address the problem of stormwater but also have additional benefits, including bringing new amenities to the community and enhancing aesthetics.

These new solutions use nature and nature’s processes to mitigate stormwater.   These practices are called green infrastructure and they are an important counterpoint to the gray infrastructure (such as cement pipes and channeled streams) that we’ve depended on in the past.   Green infrastructure is now being used throughout the country with major initiatives underway in every large city.

Green infrastructure is bringing new life to blighted urban landscapes.  Vacant lots are being transformed into community gardens watered by stormwater collection systems.  Rain gardens bring splashes of color to the neighborhood while slowing down runoff and are building neighborhood pride.  Urban forestry programs are being revitalized with the recognition that trees not only absorb large quantities of rainfall in their root system, but also help decrease stormwater runoff.  These tree canopies also provide shade, giving needed heat relief in the summer.

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Consider what happens after it rains – pesticides, pet waste, gutter debris, street runoff and more all contribute to polluting our water. Image credit:

Why all of this attention on stormwater runoff?

Because it has become the largest source of pollution entering our rivers and streams.

As stormwater flows over pavements, across rooftops, runs over lawns, and over farm fields, it picks up various kinds of pollution along the way – pesticides from lawns, fertilizer on agricultural fields, salt from sidewalks, and car fluids dripping onto our streets.  These pollutants are then carried into the storm sewers and discharged into rivers and streams.

One of the best ways to deal with stormwater pollution is to keep stormwater from running off the land – whether that land is farm fields, rooftops, streets, lawns or parking lots. That is exactly what green infrastructure does – keeps rainfall on the place where it falls.

Rain water can be soaked into the ground using practices like rain gardens, trees and native plants, or collected from rooftops and gutters using rain barrels or cisterns; or it can be trapped on rooftops with green roofs.  Other green infrastructure practices replace hard surfaces like concrete and asphalt with new surfacing materials such as pavers and permeable concrete and porous asphalt that enable the rain to soak into what normally is an impervious surface.

So, if green infrastructure is a good way to address stormwater pollution, is it being used as much as possible?

Unfortunately, no.

What stands in the way of green infrastructure being used?  The answer to that question is what our pilot project aimed to find out.

Regulations regarding land use and development are enacted at the local level of government.  Municipal codes and ordinances address a vast array of details about land use and development – from street widths, lawn heights, and the species of plants that can be used for landscaping, to the number of parking spaces per business, as well as the dimensions of those parking spaces.

It is in these very specific local regulations that barriers to green infrastructure are found.

Working with our municipal partners, our project team reviewed local regulations with a keen eye to ferret out codes and ordinances that prohibited or limited the use of green infrastructure.  We also highlighted those areas of local regulations that didn’t mention green infrastructure at all – a different kind of problem which also has the impact of limiting green infrastructure implementation.   Simply, if the option to use green infrastructure isn’t mentioned in an ordinance, it usually isn’t considered – out of sight, out of mind.

rain barrels
Rain barrels installed to capture and store rooftop rain water.

Over the last two years, we’ve worked with 13 municipalities in the Menomonee and Kinnickinnic River watersheds in a process that has led to many changes in local codes.

Our process was straight forward:

  • review the codes with the most up-to-date understanding of the relationship between local regulations and green infrastructure;
  • develop very specific and customized recommendations for code and ordinance amendments;
  • provide strategies to help the municipalities adopt the recommendations.

Our approach was equally important:

  • engage the municipal partners at each phase of the project;
  • seek to understand green infrastructure from their point of view;
  • work through the process with the municipal staff as a team with no hidden agendas.

The approach fostered dialogue between different municipal departments and helped us to better understand the community attitudes and preferences about green infrastructure, which in turn helped us best prioritize the recommendations.

Shorewood installed this effective bio-swale with native plants to infiltrate stormwater and keep it out of the sewer system.

With the success of our pilot project under our belt, we’re expanding our work to the other watersheds in the Greater Milwaukee River watershed.  We received additional financial support from the Milwaukee Metropolitan Sewerage District and the Wisconsin Coastal Management Program enabling us to begin work in the Milwaukee River watershed this fall, with work to follow this spring in the Root River and Oak Creek watersheds.

Watch for more updates over the next several months.   We’ll be writing more about the codes and ordinance project; discussing in-depth each phase and the major lessons we learned.

Learn more about our watershed protection work.