Total Maximum Daily Loads (TMDL)
Welcome to the Montana Department of Environmental Quality's Total Maximum Daily Load (TMDL) Home Page. A TMDL is both a way to quantify water quality problems and a tool to help solve those problems.
Montana’s rivers, streams, and lakes are highly prized, for their beneficial uses for recreation, aquatic life, drinking, agriculture, and industry. However, some Montana waters do not meet state water quality standards and designated beneficial uses. These are problems that affect everyone. TMDLs are designed to help define solutions to these problems.
The Montana Water Quality Act requires DEQ to develop Total Maximum Daily Loads (TMDLs) for streams and lakes that do not meet, or are not expected to meet, Montana Water Quality Standards. A TMDL is the maximum amount of a pollutant a water body can receive and still meet water quality standards. The goal of TMDLs is to eventually attain and maintain water quality standards in all of Montana’s streams and lakes, and to improve water quality to levels that support all state-designated beneficial water uses. Understanding TMDLs Pamphlet (PDF 0.6MB) provides additional information on how TMDLs are developed.
The DEQ is using a watershed approach to facilitate development of TMDL water quality plans, which means that many rivers, streams, and lakes could be addressed in a single TMDL document. DEQ has divided the state into multiple project areas, which can be seen on the TMDL Project Area Status map.
Completed plans provide a framework for effective implementation that can lead to water quality improvements. Ideally, the TMDL and associated information within the document will be used by a local watershed group and/or other watershed stakeholders as a tool to help guide and prioritize local water quality improvement activities.