Project Sponsor
City of Coeur d’Alene
Purpose
The city of Coeur d’Alene installed a stormwater storage and filtration system to divert stormwater runoff from an existing outfall. They also addressed a sediment source to the outfall to reduce sediment loading to the lake.
The Third Street outfall discharges stormwater from 240 acres of city streets and parking areas, including downtown alleys. The outfall currently releases this stormwater, untreated, by the Third Street boat launch next to McEuen Park. While all stormwater carries pollutants as it passes over residential yards, city parks, sidewalks, and streets, this area includes special considerations related to higher runoff volumes due to a high concentration of impervious/paved surfaces from downtown streets and alleys. In addition, large rainfall events have overwhelmed the capacity of this storm system in recent years, causing localized flooding.
Even with these management measures in place, residents and visitors must be mindful about daily habits such as fertilizer use and waste disposal. Less pollution to capture and filter means less maintenance time and cost. Filtration systems can be overwhelmed, increasing the possibility that phosphorus and other pollutants in stormwater can reach Coeur d’Alene Lake.
Funding
This project received $413,143 from Governor Little’s Leading Idaho initiative.
Current Status
This project is complete. The sediment source identified at the outfall has been stabilized. A stormwater retention area at Phippeny Park is complete, which diverts stormwater from a significant portion of the drainage area that discharges to this outfall. An informational sign will be installed at Phippeny Park in summer 2026.
Outcome
Currently, the funding available is not sufficient to treat stormwater from the entire drainage area, but this project is expected to reduce phosphorus loads to Coeur d’Alene Lake by at least 35 pounds annually. As the city secures more funding in the future, the treatment capacity will be expanded.