Total Maximum Daily Load
A Total Maximum Daily Load, or TMDL, is the calculated pollutant amount that a water body can receive and still meet water quality standards. In the Willamette River, temperature, bacteria and mercury have been identified as problems for water quality. The Willamette TMDL defines how much of each of these pollutants a river or stream in the Willamette basin can receive and still meet water quality standards.
The TMDL for temperature poses the greatest difficulty for the regional wastewater program. The most cost effective and environmentally beneficial way of addressing the temperature TMDL is through mitigation strategies including diverting treated wastewater to beneficial uses, shading projects to reduce heat from the sun, and restoration or enhancement projects of the natural river systems that cool water.
