Help - Basin Sizer
Basin Sizer was designed to help find sizing information for volume and flow based BMPs.
Click on a heading to get information on that topic
Accessibility Assistance: Caltrans makes every attempt to ensure our documents are accessible. Due to variances between assistive technologies,
there may be portions of this document which are not accessible. Where documents cannot be made accessible, we are committed to providing alternative
access to the content. Should you need additional assistance, please contact Joshua Gualco at (916) 956-4732. For additional information visit
https://dot.ca.gov/request-ada-compliant-documents.
Map and Layers +
Additional information can be found by adding layers to the map, This can be accomplished by clicking on the layer names to the left of the map.
Below are descriptions of the layers and their data sources.
- 1-Year 1-Hour Design Storm – This layer has the design storm for sizing BMPs to capture trash.
- Caltrans Districts – This layer shows Caltrans district boundaries.
- Caltrans Facilities – This layer shows park & ride lots, rest areas, and vista points operated by Caltrans.
- Caltrans Postmiles – This layer shows postmiles from Caltrans ArcGIS REST Services.
Post Mile Lookup +
The Post Mile Lookup Tool can be used to plot post mile locations.
Post mile prefixes:
- C: Commercial Lanes (Trucks)
- D: Duplicate post miles at county lines
- G: Reposting of duplicate post mile at the end of a route
- H: Realignment of D mileage
- L: Overlaping post miles
- M: Realignment of R mileage
- N: Realignment of M mileage
- R: First realignment
- S: Spur mileage of original or realign mileage
- T: Temporary connection of orginal or realign mileage
Change Log +
June 2023
July 2023
- Added 1-year 1-hour design storms for trash
- Added accessibility language
October 2023
February 2024
January 2025
- Updated 85th Percenite 24-hour storm data
For more information contact
Division of Environmental Analysis, Stormwater Unit
California Department of Transportation
P.O. Box 942874, MS-27
Sacramento, CA 94274-0001
Email:
