Stormwater Resources

Stormwater runoff occurs when precipitation from rain or snowmelt flows over the ground. Impervious surfaces like driveways, sidewalks, and streets prevent stormwater from naturally soaking into the ground.

Stormwater can pick up debris, chemicals, dirt, and other pollutants and flow into a storm sewer system or directly to a lake, stream, river, or wetland. Anything that enters a storm sewer system is discharged untreated into the water bodies we use for swimming, fishing, and providing drinking water. Polluted stormwater runoff can have many adverse effects on plants, fish, animals, and people.

On-site retention and infiltration of stormwater using best management practices such as rain gardens, pervious pavement, and rain barrels decreases the surge of water to rivers and streams after rain events. These practices can reduce flooding in rivers and streams. To learn more about Polk County’s flood control program, visit the Be Flood Smart! web page.

Polk County administers a Stormwater Management Program (SWMP) for the area of Polk County located within the City of Salem urban growth boundary (UGB). This program is currently being updated to meet the Municipal Separate Storm Sewer System (MS4) Phase II General Permit requirements of the National Pollutant Discharge Elimination System (NPDES), which became effective on March 1, 2019. Polk County also implements a Total Maximum Daily Load (TMDL) Implementation Plan. The TMDL Implementation Plan is designed to reduce river and stream temperatures as well as the levels of bacteria and mercury that enter County rivers and streams. The TMDL Implementation Plan applies county wide. If you would like to learn more about Polk County’s SWMP or TMDL Implementation Plan, please contact Polk County Community Development at (503) 623-9237 or the Public Works Department at (503) 623-9287.

Post-Construction Best Management Practices

Roof tops, parking lots, and driveways create impervious surfaces that concentrate stormwater run-off. Stormwater flowing over these developments pick up oil and other particle matter that can be harmful to riparian ecosystems. In order to decrease the quantity and increase the quality of stormwater that enters the County rivers and streams, construction operators should plan how to minimize stormwater runoff from new development prior to beginning construction. The following links provide technical guidance in implementing practices that can be used to minimize the impact of development on County rivers and streams:

Maintain native vegetation along rivers, streams, and sloped areas of your property:

Trees and other vegetation provide stream bank stability and minimize erosion caused by rain events. Streamside vegetation shades the stream itself, thereby acting to reduce stream temperatures, and provides a natural filter for sediment that becomes suspended in stormwater.

Vegetated/Grassed Swales:

EPA Swale Information

California Stormwater Quality Association Guidance

Online training courses are available through the EPA website.

Total Maximum Daily Load (TMDL):

2023 Annual Report (Feb. 2024)
Cover Letter
Attachment A: 2023 Implementation Planning Matrix for Temperature and Bacteria
Attachment B: 2023 Implementation Planning Matrix for Mercury
Attachment C: Mercury Matrix (Revised February 2024)

2022 Annual Report and Five-Year Review (Feb. 2023)

2021 Annual Report (Feb. 2022)
Cover Letter
Attachment A: 2021 Implementation Planning Matrix
Attachment B: Implementation Plan
Exhibit 1: Implementation Planning Matrix

2021 Implementation Plan (Draft)
2021 Implementation Tracking Matrix (Draft)

2020 Annual Report (Feb. 2021)
Cover Letter
Attachment A: 2020 Implementation Planning Matrix
Attachment B: Revised Implementation Plan
Exhibit 1: Revised Implementation Planning Matrix

Implementation Plan, Revised Feb. 2021 (Draft)
Implementation Tracking Matrix (Draft)

2018-2022 TMDL Implementation Plan (February 2018 Draft)

Supplemental Draft Documents Revised November 2018
5 Year Evaluation and Review Report (Appendix A)
TMDL Implementation Plan (Appendix B)
Implementation Matrix (Exhibit 1)
Updated Parks List (Exhibit 5)
Survey

Stormwater Management Program (SWMP):

Polk County's Stormwater Management Program (SWMP) was created for the area located within the City of Salem Urban Growth Boundary (UGB) and outside city limits, within Polk County's jurisdiction. This program is currently being updated to meet the Phase II Municipal Separate Storm Sewer System (MS4) General Permit requirements of the National Pollutant Discharge Elimination System (NPDES). A draft version of the SWMP can be found here. Public comments for this draft SWMP can be submitted to Sidney Mulder at mulder.sidney@co.polk.or.us, or to the Polk County Community Development Department at 850 Main Street, Dallas, OR.

Illicit Discharge Complaints

As required by Polk County Code of Ordinances (PCCO) 43.057, other than the few exceptions specified, no person shall throw, drain, or otherwise discharge into the storm sewer system any pollutants or waters containing any pollutants, other than stormwater.