The Water Resources Department reviews proposed developments to minimize flooding and drainage impacts to the development and to minimize impacts to other properties. The Department's review is subject to the requirements of California drainage law, the County Code, and the California Environmental Quality Act (CEQA). County Code chapters of primary concern are:
Projects under County jurisdiction are usually developed under the lead of the Community Development Department pursuant to Chapters 17 and 21 of the County Code and CEQA. Projects subject to review requirements are circulated by the responsible agency for input on potential impacts and to determine what mitigation measures are necessary. Drainage review incorporates the following issues:
Determine if the project is within a Special Flood Hazard Area, or SFHA (1% annual chance flood or 100-year flood). If a project is within a SFHA, it must be in compliance with Chapter 25, Floodplain Management. Chapter 25 identifies requirements for new development to minimize future flood damages.
Drainage Plans & Mitigation
If the project includes significant grading and construction of drainage facilities, or facilities that may affect drainage, a drainage plan may be required. Depending on the size of the project, the grading plan may be required to be engineered.
If the project's impact on drainage patterns and/or systems are potentially significant, mitigation may be required. Changes in flow direction, flow velocity, water quality or significant changes in quantity of flow may warrant mitigation. Mitigation may occur on-site or off-site, or any combination thereof. If impacts are significant, and the proposed project does not does not address mitigation, preliminary drainage plans may be requested prior to approval of permits.
Final drainage plans for the project must be approved prior to start of construction.