DEQ outlines TMDL history and next steps for North Fork Payette subbasin; seeks local advisory group input

The Idaho Department of Environmental Quality on Monday reviewed the Total Maximum Daily Load (TMDL) process for the North Fork Payette River subbasin and requested local participation as it prepares new TMDLs and five-year reviews for impaired streams and reservoirs.

Vanessa Johnson, a DEQ staff member, told the Valley County Board of Commissioners that the agency submitted the draft 2024 Integrated Report to the U.S. Environmental Protection Agency and is awaiting EPA approval. "Once listed on the integrated report, a TMDL is written to address each of the pollutants causing the impairments in the category 5 waters," Johnson said.

Johnson said DEQ’s work in the North Fork Payette subbasin dates back to the mid-1990s and includes watershed management plans, TMDLs, implementation plans and five-year reviews. "There has been TMDLs written or watershed management plans written for nutrients, pH, dissolved oxygen, sediment, and temperature impairments," she said, summarizing documents from 1996, 1998, 2000, 2009, 2011 and 2018.

Why it matters: The subbasin includes North Fork Payette River above and into Payette Lake and is divided into 78 assessment units. Johnson said 17 units previously addressed are in category 4A, and the 2024 draft…