Subwatershed Stormwater Retrofit Assessment

Stormwater runoff poses a significant threat to water resources throughout Anoka County. Stormwater volume and pollutant loads that are carried to receiving water bodies via stormwater infrastructure can have devastating effects on water quality and surrounding habitat.

In response to these issues, ACD staff conduct subwatershed stormwater retrofit assessments to identify retrofit opportunities in subwatersheds that are significant contributors to the degradation of high priority water bodies. Projects identified as part of the assessment process improve water quality, increase groundwater recharge, and reduce stormwater runoff volumes throughout Anoka County.

Subwatershed Stormwater Retrofit Assessment Process*

*Process modified from The Center for Watershed Protection’s Urban Stormwater Retrofit Practices (2007) manual

Step 1: Assessment Scoping – Refine the retrofit strategy to meet local restoration objectives

• Define core retrofitting objectives
• Identify preferred retrofit treatment options
• Delineate subwatershed focus area

Step 2: Desktop Analysis – Search for potential retrofit sites throughout the subwatershed

• Secure GIS and other mapping
• Conduct desktop search for potential retrofit sites
• Prepare base maps for field reconnaissance

Step 3: Subwatershed Reconnaissance – Investigate retrofit sites in the field

• Verify drainage areas and mapping data
• Assess site constraints
• Search for additional retrofit opportunities

Step 4: Treatment Analysis/Cost Estimates – Create project concepts and model for treatment potential

• Develop project concepts and cost estimates
• Model for volume and pollutant reduction

Step 5: Evaluation and Ranking – Compare projects throughout the subwatershed

• Conduct cost/benefit analysis for project concepts
• Rank projects by cost-effectiveness
• Compare results to restoration objectives

Step 6: Reporting – Create detailed report of assessment findings and recommended projects

• Deliver final report to project partners
• Conduct one verbal presentation of assessment findings to project partners

Since 2009, ACD staff have completed 9 subwatershed stormwater retrofit assessments. Targeted high priority water bodies have included creeks, rivers, and lakes. See the Projects tab for the complete reports.

Cities, watershed districts, watershed management organizations, or other local groups contract with the ACD to complete these assessments. Often, these groups do not have staff with expertise in stormwater, so hiring the ACD is cost effective for all.

ACD Contact : Jamie Schurbon763/434-2030 ext. 12

ACD Contact : Nate Zwonitzer 763/434-2030 ext. 11

 

Anoka Conservation District
1318 McKay Dr NE, Suite 300, Ham Lake, MN 55304
763/434-2030 | Fax: 763/434-2094