AN ECOLOGICALLY-BASED STORMWATER BMP

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In 2023, a nature-based design and installation was commissioned by the Alliance within a floodplain area between the West Fork – White River and a Fayetteville suburban neighborhood to address and treat stormwater. A 60-acre parcel of land owned by a private conservation-minded landowner sits between the suburban development and the river. It is zoned for agriculture, subject to the city floodplain requirements, and is under a conservation easement. Stormwater from the existing neighborhood exits onto the site through a 3′ diameter stormwater outfall. Before the installation of this project, vegetation consisted of non-native, cool-season grasses mowed annually for hay.

The Watershed Conservation Resource Center (WCRC) and Bio by Design were contracted to develop a design to restore a portion of this 60-acre site to rejuvenate the riparian and floodplain. This site was once home to a lowland prairie landscape. Arkansas had over 700,000 acres of tallgrass prairie, but less than 0.5% remains today. Prairies are made up of diverse native plants with deep root systems, perfect for holding soil in place and acting as sponges that soak up water which can decrease the severity of flooding.

A natural feature found in many prairies are upland prairie mounds and depressional areas. Between the mounds water seasonally ponded to form wetlands. Such prairie mounds and wet prairie depressions were common in the area prior to the western expansion by settlers in the early to mid 1800’s. These topographical variations help support a diversity of native vegetation along with amphibian and reptile species. Mounds and depressions were natural stormwater treatments that took on floods and river surges.

The design team used history, watershed data, nature-based process methods, and modeling to design the site to restore prairie mounds and depressions and mitigate the stormwater runoff from the neighborhood. Because there was a lift in soil amendments for the mounds, the team worked with the City of Fayetteville and was approved for a floodplain variance. The designs also included the removal of invasive plants and establishment of native species.

Upon approval by the City and landowner, WCRC installed the nature-based features last fall (2023) and planted them in the spring of 2024. The adjacent neighborhood residents were also a part of the process from day one, with educational community meetings and follow-ups on the project provided.

The Alliance is very excited to see the completion and success of this project. This project demonstrates the possibilities for creative, ecological, nature-based stormwater management that will be useful for other existing and future developments adjacent to riparian areas and floodplains in the watershed. The effectiveness of this nature-based project is expected to be highly beneficial for water quality. Estimated reductions in sediment and nutrients are an expected outcome and outlined in the project’s final report (link above), but to call out, estimated Total Suspended Solids reductions are 88%, estimated Total Nitrogen reductions are 41%, and estimated Total Phosphorous reductions are 76%.

We would like to thank project partners, supporters, and funders of this nature-based design project including The City of Fayetteville, Beaver Water District, Walton Family Foundation, Ozark Land Trust, Bio x Design, Watershed Conservation Resource Center, Josh Brown, and neighboring residents.

Details

Project Start

2023

Location

Fayetteville, AR

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