Total Maximum Daily Load

What is TMDL?

Under Section 303 of the Federal Clean Water Act, states must set water quality standards. When an Oregon water body doesn’t meet these standards, the Department of Environmental Quality (DEQ) creates a Total Maximum Daily Load (TMDL) to limit the pollutant causing the issue.

A TMDL defines the pollution limit needed to meet water quality standards. DEQ assigns limits to both point sources, like wastewater plants, and nonpoint sources, such as runoff from farms and cities.

Local agencies, called Designated Management Agencies (DMAs), must develop plans to reduce pollution and meet these limits, ensuring cleaner water for everyone.

TMDL Implementation Plan, Feb. 28, 2022