The City of Monona, Iowa (pop. 1,549), built its aquatic center long before joining with 34 other stakeholders to revitalize its watershed. Budget limitations precluded grading and paving the facility’s parking lot, so public works put down crushed stone instead. Whenever it rained, the inevitable happened: Sediment, oil, and other pollutants washed into Silver Creek, which feeds a Mississippi River tributary.
In 2003, not many people thought about the consequences of erosion or pollutants in stormwater from non-point sources. Things were much different a decade later, however. Flooding from Mississippi River tributaries, which has long been a problem, had worsened because of more intense rainfalls. The Turkey River usually winds placidly along northeast Iowa farmlands and small towns, but storms overwhelm rural stormwater collection systems and sweep agricultural nutrients toward the Gulf of Mexico, the nation’s largest “dead zone.”
In 2009, the state centralized flood-control and water-quality efforts in the Iowa Flood Center at the University of Iowa in Iowa City, which is using a watershed-based approach to meeting regulatory requirements. To facilitate this, the center identifies federal funding sources that apply to farmers as well as municipalities and works with state agencies to remove obstacles that hinder access by the small towns that need support the most.
For example, the center began acquiring U.S. Department of Housing and Urban Development Community Development Block Grants for stakeholders in the state’s 57 watersheds to band together to develop mitigation plans and apply for project funding. In 2012, Monona became one of 23 communities, seven soil and water conservation districts, and five counties that comprise the Turkey River Watershed Management Authority, which oversees more than 1 million acres in seven counties.
The center also worked to expand the list of eligible Clean Water state revolving fund (SRF) projects from building and improving sewer assets to projects that keep sediment, nutrients, and chemicals out of streams and lakes. In January 2013, the state legislature allocated $15 million in loan funds every year for watershed-protection practices such as stream buffers, wetland restoration, and green infrastructure.
Ten months later, Monona’s new aquatic center parking lot became the first Water Resource Sponsored Project to be completed in Iowa.
Taking advantage of new opportunities
In 2014, Monona applied for a $2.6 million revolving-fund loan to upgrade its 80,000-gallon-per-day wastewater treatment plant. Installed in 1985 when the plant was built, pumps and valves were having trouble managing flows to meet the city’s National Pollutant Discharge Elimination System (NPDES) permit requirements.
Staab Construction was working on electrical system and equipment improvements when public works learned about the changes to the loan program. Administered by the Iowa Department of Natural Resources (DNR) and the Iowa Finance Authority with technical assistance from the Iowa Department of Agriculture and Land Stewardship (IDALS), the sponsored-project provision allows cities to use a percentage of interest from community infrastructure loans to install best management practices that improve water quality.
The West Union, Iowa, office of Fehr Graham was hired to provide solutions for improving the parking lot’s condition. Grants weren’t available to replace the crushed stone with asphalt or concrete, but those surfaces wouldn’t have slowed runoff or improved water quality anyway. The engineering and environmental firm recommended using permeable pavers for the parking lot and sidewalk and installing native, deep-rooted vegetation on the steep perimeter slopes to capture excess runoff. Because they allow rain to filter into the ground rather than flow into the creek, pavers were one of the products eligible for funding under the expanded loan program.
In addition to environmental benefits, the $260,000 project would improve the lot’s aesthetics.
Armed with this plan, the city applied for an additional $245,000. Under the sponsored-project provision, the interest rate was lowered so the city won’t pay more than originally financed and gets approximately 10% of the loan amount to use for the parking lot improvements.
Success breeds success
Fehr Graham worked closely with Iowa DNR, IDALS, and Northeast Iowa Resource Conservation & Development to ensure all activities met regulatory requirements.
Permeable pavement is the design’s primary stormwater-management feature. Because the location’s native soils are clay-based with low permeability, a crushed-stone base is used to infiltrate rain and control runoff velocity by detaining stormwater. A crushed-stone reservoir installed at the lot’s downstream end to store a 100-year rainfall event has a gate valve to control release of excess flows from no discharge to full pipe capacity. Normally, the valve is set slightly open for slow release but can be opened for line cleaning.
The lot’s entrance was moved from the north side to the much flatter east side, providing a safer and more efficient traffic pattern. The space now accommodates 45 vehicles instead of roughly 25 vehicles and meets Americans with Disabilities Act requirements. Colored pavers enhance aesthetics and delineate parking stripes and accessibility symbols, making them permanent and reducing future maintenance costs for repainting.
By proving permeable pavers function effectively with soils that have a low infiltration rate, the project provided information that other small towns can use to address their stormwater and/or regulatory challenges. By being creative with the overall design – using additional underground storage, controlling discharge by valving, and improving aesthetics via paver color and style – a simple project can become a tremendous asset to a community.
Residents and elected officials were so pleased that public works did another project. In 2016, the city received $165,000 to improve a crushed stone street next to the aquatic center that was experiencing increased traffic because of commercial development.
Fehr Graham was brought in again to consult. Once again, the firm recommended permeable pavers for the majority of the street length. Once again, a gate valve was installed to control runoff rate from the storage aggregate below the pavers. Synthetic baffles placed along the steeper portion of the street slow movement of stormwater within the crushed stone.
Residents have commented positively on the change and more vehicles are using the road.
Formalizing development expectations
Monona didn’t have a stormwater ordinance before the parking lot project. Some areas occasionally flood; but for the most part, because there isn't a large stream within city limits, large-scale flooding isn’t an issue.
Officials learned the importance of stormwater management when Monona became a member of the Turkey River Watershed Management Authority. The negative effects runoff has downstream became clear, as did the significance of being a good neighbor. Once members saw the parking lot project’s benefits, the city council adopted an ordinance designed to reduce peak runoff from subdivisions and commercial/industrial development. In addition to minimizing erosion during construction, the language saves taxpayer dollars by reducing the size of required collection-system improvements.
In the two years since adoption, the ordinance has been used on a residential subdivision and three commercial properties. In one instance, unchecked runoff from a commercial development could have caused problems for downstream property owners. Another small northeast Iowa town is using the ordinance as a model for lessening its impact on communities downstream.
The Turkey River Watershed Management Authority and Iowa DNR shares the results of these sponsored projects to show what even small communities with limited budgets can do to move the needle on regional and statewide environmental goals.