Precipitation design standards; non-stationary precipitation, climate-adjusted rainfall.

Precipitation design standards; non-stationary precipitation; climate-adjusted rainfall. Requires the State Water Control Board to serve as the lead agency responsible for establishing and maintaining precipitation design standards to be used by all state agencies, localities, and other political subdivisions and in transportation projects. The bill requires such precipitation design standards to include the most recent precipitation frequency estimates published in the National Oceanic and Atmospheric Administration national precipitation frequency atlas to account for observed and projected increases in precipitation intensity, frequency, and duration.

The bill directs the Department of Environmental Quality, Department of Transportation, and any other state agency to update any relevant manuals and design standards consistent with the provisions of the bill by July 1, 2027. The bill also allows the State Water Control Board and the Department of Transportation to adopt interim guidance or regulations implementing the provisions of the bill consistent with the Administrative Process Act, ensuring that updated precipitation design standards take effect no later than July 1, 2027. This bill is a recommendation of the Joint Subcommittee on Recurrent Flooding.