Almost every watershed in Contra Costa County has been identified with a number. We call these Drainage Areas. Drainage Areas are formed to collect fees from developers to pay for planned drainage infrastructure including detention basins, pipes, channels, and related costs. An unformed drainage area is a watershed that has been identified, but does not have development fees.
You can use http://www.ccmap.us to view the drainage area boundaries in the Interactive Map. Enter an street address or a Assessor's Parcel Number (APN) at the bottom to start the interactive map. Then, zoom in or out as needed. Click "Layers" at the top left and then click the box by "Drainage Boundaries" on the right. You will have to turn off your popup blocker or add the ccmap site to your allowed popup list.
Drainage Area Maps
Copies of Drainage Area Maps can found and prints ordered at the County Public Works Records Division office where the Flood Control Division also resides. For directions, click here.
The Drainage Area Boundary Map shows the legally described area for the DA Parcels within that Boundary. These parcels are noted in the Assessors Parcel database so that the District which parcels are legally in the DA.
The Drainage Area Land Use Map shows the land use assumptions used in the hydrology calculations for the Drainage Area. The LU Map is based on General Plan at time of calculations.
The Drainage Area Hydrology Map shows the watershed and sub-watershed boundaries and assumed direction of drainage.
The Drainage Area Plan shows the proposed improvements to be funded by the drainage area, typically storm drain pipes and detention basins. The Hydrology Map and Plan maps are sometimes combined.