In order to minimize pollution and other impairments, the state has assigned Total Maximum Daily Loads (TMDL) to many of our waterways. A TMDL identifies how much pollutant a body of water can effectively absorb before water quality standards are exceeded.
The Total Maximum Daily Load (TMDL) process leads to a "pollution budget" designed to restore the health of a polluted or impaired body of water. The TMDL process provides a quantitative assessment of water quality problems, contributing sources of pollution, and the pollutant load reductions or control actions needed to restore and protect the beneficial uses of an individual water body impaired from loading of a particular pollutant. More specifically, a TMDL is defined as the sum of the individual waste load allocations for point sources, load allocations for non-point sources, and natural background such that the capacity of the water body to assimilate pollutant loading (the loading capacity) is not exceeded (40 Code of Federal Regulations (CFR) §130.2). - North Coast Regional Water Quality Control Board