Urban Project Provides Water Quality Benefits - Denison, Iowa

With assistance from a Water Quality Initiative Urban Demonstration Project grant, the City of Denison recently constructed a series of bioretention cells and permeable pavers in a downtown parking lot to capture runoff from the lot and adjacent buildings. Before these urban storm water practices were installed, the parking lot contained no storm water management and relied upon a traditional stormsewer system that diverted runoff into the Boyer River.

This highly visible parking lot is centrally located downtown and utilized by many surrounding businesses and residents. With the amount of storm water runoff from this area and the water quality issues it caused, the City turned to the help of IDALS Urban Conservationists to find a solution. Through the planning and construction efforts of multiple partners, four bioretention cells and a strip of permeable pavers were installed in the parking lot to provide this area with proper storm water management and treatment to improve water quality.

The entire parking lot and all downspouts from surrounding buildings flow into the permeable pavement system or outlet directly into the bioretention cells. To complete the project, over 600 plants were planted in the bioretention cell with the help of the Crawford County Soil and Water Conservation District, Crawford County Master Gardener Program, and the Denison High School FFA students. The plantings help the cells function more effectively by up-taking nutrients and other contaminants found in storm water.

After the completion of the permeable parking lot, a ribbon cutting ceremony was held to demonstrate urban storm water management and educate the public about Denison’s role as a partner in Iowa’s Nutrient Reduction Strategy implementation. Representatives from the city along with Urban Conservationists Derek Namanny and Hannah Vorrie spoke about how the practices work and why they are important.

This project is in combination with 33 other Urban WQI projects that have been approved since 2015. In total IDALS has contributed $2.45 million towards the urban projects that has been matched with $6.22 million from other funding sources.  The diverse range of projects covering the state demonstrates the ability of both urban and rural communities to work together to accomplish water quality and nutrient reduction goals. Additional information on this and other Urban WQI projects may be found here https://www.cleanwateriowa.org/urban-1/