Water Quality Programs

There are several distinct, yet related, water quality efforts in Benton County.  For more information, please select the program titles or buttons below.

Stormwater Program

The Stormwater Program as outlined here is specifically affiliated with the National Pollution Discharge Elimination System MS4 Phase II Stormwater Discharge Permit.  A municipal separate storm sewer system, also known as an MS4, is a conveyance or system of conveyances, such as roads with drainage systems, municipal streets, catch basins, curbs, gutters, constructed channels or storm drains, owned or operated by a governmental entity that discharges to waters of the state. Benton County is one of several select jurisdictions that has been classified as an MS4 Phase II, which is regulated by the State of Oregon Department of Environmental Quality. Phase II (small) MS4s serve populations less than 100,000 and are located within a Census Bureau designated "urbanized area" (UA).  The actions and efforts of the County towards water quality improvement is monitored under the National Pollutant Discharge Elimination System (NPDES) MS4 Phase II Stormwater Discharge Permit.  Under the initial permit in 2007, Benton County adopted a Stormwater Management Program for the Corvallis Urbanized Area. The plan was subsequently modified in 2012 in response to a permit renewal process.  Currently, the County will be modifying the program to be in compliance with the most recent permit that became effective March 1, 2019.

TMDL Program

Benton County is also regulated by the State of Oregon’s Total Maximum Daily Load requirements for the Upper Willamette Mainstem, which is a 303(d) listed waterbody.  Benton County has been categorized a Designated Management Agency (DMA) which means the County has legal authority over a sector or source that contributes pollutants to the system.  The Benton County TMDL Implementation Plan focuses on general applications that will benefit the Upper Willamette River Subbasin which will in turn benefit the mainstem of the Willamette River.

Riparian Protection Project

As an offshoot of the NPDES Program, Benton County has worked since 2009 to inventory and evaluate priority riparian (streamside) corridors, while developing and implementing outreach and education to support protection and enhancement of riparian resources. Protecting riparian and wetland areas is important to the environmental and economic health of the County. Residents value Riparian and Wetland area mapping and planning and requested that Benton County staff focus on the inventory and protection of riparian and associated wetland resources The goal of the voluntary protection of riparian buffers is to provide benefits to fish, wildlife, water quality and many other natural resources.