Under our Northern California Retainer with the Department General Services (DGS), Horizon is preparing a handbook to support the environmental review of proposed total maximum daily loads (TMDLs) for water bodies on the State’s list of impaired water bodies pursuant to Section 303(d) of the federal Clean Water Act. DGS is overseeing this project, which is funded by the State Water Resources Control Board (SWRCB). The Regional Water Quality Control Boards (RWQCB) are required to evaluate environmental impacts of the methods of compliance that would be implemented under proposed TMDLs, pursuant to CEQA. Horizon is conducting the following tasks for this project:

  • Developing a database of information from existing TMDLs
  • Obtaining input from end users of the proposed handbook
  • Preparing the draft and final handbook

Database Development

The database will present information from existing environmental documents that were prepared for a sample of TMDLs. Information in the database will include methods of compliance identified in each TMDL, environmental impacts anticipated to result from the methods of compliance, and examples of avoidance, minimization and mitigation measures to address potential impacts.

End User Coordination

Horizon is coordinating with SWRCB staff to obtain input from representatives of the nine RWQCBs. Staff members from the RWQCBs  (end users of the handbook) are providing input on information to include in the handbook and how to format the handbook.

Handbook Preparation

The handbook will include fact sheets for a range of reasonably foreseeable methods of compliance. The fact sheets will be based on information from the TMDL database developed by Horizon, supplemented by information from other sources.

Total Maximum Daily Load Handbook

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