Laguna Watershed Knowledgebase

The Laguna de Santa Rosa (Laguna) watershed is listed on the current California Section 303(d) list of impaired waterbodies for excessive nutrients (nitrogen and phosphorus) and sedimentation, low dissolved oxygen (DO), high temperature, and mercury contamination. Placement of a waterbody on the Section 303(d) list triggers the development of a Total Maximum Daily Load (TMDL). A TMDL is a framework for assessing the factors and quantifying the sources contributing to the water quality impairment and for developing a strategy for attaining and maintaining water quality standards. Staff of the North Coast Regional Water Quality Control Board’s (Regional Water Board) Total Maximum Daily Load (TMDL) Development Unit are scheduled to complete the technical analyses for the Laguna TMDLs for each of the listed impairment except mercury by 2011. The Laguna is currently being studied to develop the TMDL staff report. California TMDL guidance identifies specific elements that must be included in the TMDL staff report. Many of these TMDL elements require the compilation of existing water quality data, as well as the collection of additional monitoring data. The presentation reviews the new monitoring completed by the Regional Water Board in 2008 and presents the monitoring currently underway in 2009.