Innovative Monitoring to Support Management Objectives in a Complex Subwatershed

Description

The Ada County Highway District (ACHD) manages stormwater infrastructure in the Boise, Idaho area. One of the largest and most complex subwatersheds in their permit area covers 900-acres of commercial and residential land use. If you can think of a stormwater management challenge, there’s a good chance it is represented here, and additional monitoring has helped provide the resolution necessary to support management objectives in this highly dynamic drainage area. Water quality and quantity challenges include redevelopment in the downtown area, aging infrastructure and high nutrient loading in the residential areas, and dry weather flows from irrigation spillbacks, groundwater pumping, natural systems, and Boise’s geothermal network. ACHD monitors flows at several key junctures in the subwatershed to better understand these flows. Outcomes from pairing low-cost subcatchment monitoring with permit-required outfall monitoring include:

• Successful alternative compliance measure implementation
• Improved illicit discharge detection and pollutant source identification
• Improved management of non-stormwater discharges
• More representative stormwater quality sampling