Help - Water Quality Planning Tool
The Water Quality Planning Tool was designed to help users find information on watersheds and water quality objectives.
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 +
The Water Quality Planning Tool allows users to find information useful for complying with the 2009 California Construction General Permit (CGP).
To find information on a site, center the map on a location of interest. You can use the controls on the left side of the map to pan and zoom in or click and drag the map using your mouse. Different types of maps can be selected using the buttons on the top right of the map. As you move around the map, information on the current location will appear below the map.
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. Where appropriate CSV files of the tables are available.
- 303(d) List and TMDLs – This layer contains water bodies that either have a TMDL or are on the 2012 303(d) list. By clicking on a water body you can get information on the pollutants and status.
This information is also repeated on the table below this map for any impaired water body in the same Hydrologic Sub-Area as the current site. The original GIS files are from the SWRCB, but many of the water body
extents have been edited by the Office of Water Programs.
- 2014-16 303(d) list from the SWRCB
- TMDL Program from the SWRCB
- Water body maps corrected by the California State University, Office of Water Programs
- Areas of Special Biological Significance – These are 34 ocean areas monitored and maintained for water quality by the State Water Resources Control Board. Discharge points are the sites listed in Caltrans' NPDES Stormwater Discharge Permit.
- Areas of Special Biological Significance information at the SWRCB
- Arid and Semi-Arid Regions – Arid regions on average receive less than 10 inches of rain per year. Semi-Arid regions receive between 10 and 20 inches. This layer can be used with the Caltrans Infiltration Tool for use in designing BMPs. The original file is from the PRISM Climate Mapping Project. It has been modified by the Office of Water Programs to only show arid and semi-arid regions.
- Calwater Watersheds 2.2.1 – This is the official watershed map for California. These watersheds form a hierarchy starting with Hydrologic Units as large watersheds that encompass the progressively smaller
Hydrologic Areas, Sub-Areas, and Planning Watersheds. The boundaries shown on the map are Planning Watersheds. All Planning Watersheds in the same Hydrologic Sub-Area are given the same color.
- Download from Cal Fire
- Caltrans Districts – This layer shows Caltrans district boundaries.
- Caltrans GIS Library
- Caltrans Facilities – This layer shows park & ride lots, rest areas, and vista points operated by Caltrans.
- Caltrans GIS Library
- Caltrans Postmiles – This layer shows postmiles from Caltrans ArcGIS REST Services.
- Caltrans ArcGIS REST Server
- Coastal Zone – This is an area in which the California Coastal Commission plans and regulates the use of land and water.
- California Coastal Commission Website
- Flood Hazard Areas
- This layer displays Flood Hazard Areas from the Flood Insurance Rate Map created by the Federal Emergency Management Agency.
- Source
- Geologic Map
- California geologic map GIS Files from the USGS
- Map legend and colors from the State of California, Department of Conservation
- High-Risk Receiving Watersheds – High-Risk Receiving Watersheds are Hydrologic Unit Code (HUC) Level 12 watersheds that drain to water bodies with one or more of the following characteristics:
1) Are on the 303(d) list as being impaired for sediment/siltation or turbidity
2) have a US Environmental Protection Agency-approved, sediment-related Total Maximum Daily Load (TMDL)
3) have the existing beneficial uses of SPAWN, MIG, and COLD according to the most recent applicable Regional Board Basin Plan
A combination of HUC Level 10 watershed boundaries and physical barriers (e.g., dams) were used to delineate the upstream extent of High-Risk Receiving Watersheds. A project located within a High-Risk Receiving Watersheds is considered to have a high receiving water risk. Identifying High-Risk Receiving Watersheds reduces the confusion over direct vs. indirect discharges and questions regarding upstream extent.
This layer was developed by the SWRCB. For more information on the Construction General Permit please visit the Construction Stormwater Program. - Monthly Precipitation – The average number of days per month with rainfall over 0.1” and 0.5” at various rain gauges is shown in this layer. This information is useful for budgeting for
rainfall events that require Rain Event Action Plans or Monitoring. The data for this layer comes from NOAA daily rain gauges.
- Daily precipitation amounts from NOAA
- Monthly totals processed by the California State University, Office of Water Programs
- Municipal Separate Storm Sewer Systems (MS4) – This layer shows MS4 areas covered by the NPDES stormwater program.
- NPDES MS4 Information
- MS4 Boundaries from the SWRCB
- Rainfall Distribution Types – This data was prepared by the USDA-NRCS based on NOAA Atlas 14 precipitation data. It identifies six distinct temporal rainfall distributions throughout California. The rainfall distribution is used by the Caltrans Infiltration Tool v 4 and newer to predict the volume of runoff from a design storm that infiltrates in a soil based TBMP.
- WinTR-20 webpage
- Soil Risk Level Determination – RUSLE2 is a program that predicts long term, average annual erosion by rainfall. The program includes many factors.
K factor is soil erodibility factor which represents both susceptibility of soil to erosion and the rate of runoff. The soil layer has detailed information on K factors.
The LS factor represents the effect of topography on erosion (i.e., soil loss), which combines the effects of a hillslope length factor, L, and a hillslope gradient factor, S. In general, as either hillslope factor increases, soil loss increases. As hillslope length increases, total soil loss and soil loss per unit area increase due to the progressive accumulation of runoff in the downslope direction. As the hillslope gradient increases, the velocity and erosivity of runoff increases.
The LS a nfd K factor layers were developed by the SWRCB. For more information on the LS and K Factors and the Construction General Permit please visit the Construction Stormwater Program
R is the rainfall-runoff erosivity factor.
- K Factor GIS Methodology from SWRCB
- LS Factor Map from SWRCB
- R Factor erosivity calculations from the EPA
- Soils – This layer contains soil information that is useful for compliance with the CGP. Click on a soil to get soil information that includes: Compaction, Hydrologic Group,
Sand/Silt/Clay Percentages, Bulk Density, and Soil Erosion Factors. Soils tend to vary in their extent and compositions. All values should be verified by on-site checks.
If you want additional information on a soil you can click the link to the California Soil Resource Lab.
- SSURGO and STATSGO data from the NRCS Soils Data Mart
- Links to soil details from the UC Davis, California Soil Resource Lab
- Soil maps processed and summarized by the California State University, Office of Water Programs
- USGS Topographic Maps
- USGS Topographic Maps
- Online maps from ESRI
- Watershed Boundary Dataset – This watershed map has been developed by the USGS and the NRCS. In some cases it provides more accurate watershed boundaries than Calwater,
but it has not been officially adopted by California.
- Watershed Boundary Dataset Home Page
- Download from Cal-Atlas
- Wetlands
- This feature layer displays wetlands of the United States from the National Wetlands Inventory produced by the US Fish and Wildlife Service.
- Source
Measure Distance and Area +
Select the measuring checkbox to begin. Then, click on the map to place points. The distance and area covered will be calculated automatically. Already placed points may be moved by clicking and dragging them.
You may have to turn off layers to place points. Uncheck the measure box when you are finished.
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
Output Tables +
Watershed Information:
These tables contain information on both the Calwater 2.2.1 and Watershed Boundary Dataset watershed maps.
TMDLs & 303(d) Listed Water Bodies:
This section lists 303(d) listed water bodies and total maximum daily loads (TMDLs) priority schedules for a hydrologic sub-area. The 2020-22 303(d) list is currently being used. This site will be updated as new lists become available.
Water bodies highlighted in orange have a TMDL. The ones shown in light blue are on the 303(d) list.
Water Quality Objectives:
Click on a water body name to see a list of water quality objectives and beneficial uses for that water body. The values are from California Basin Plans.
Caltrans Facilities:
All Caltrans facilities located in a hydrologic sub-area are listed here.
Change Log +
October 2012
- Migrated Google Maps from version 2 to version 3
- Moved high risk receiving waters information from watershed information tables to a new map layer
- Separated Calwater watershed information from the Watershed Boundary Dataset table
- Added average number of days per year with precipitation to the precipitation layer
- Updated the help page to state that the WQPT is using the 2010 303(d) list not the 2006 list
- Reduced the transparency of the watershed boundary dataset layer
- Added descriptions of the Calwater and Watershed Boundary Dataset
- Added code to allow the map to resize with the browser window
- Added USGS topographic maps as a layer
- Added a list showing the sources of the layers and data tables to the help page
- Added a legend to the 303(d) listed water bodies layer
- Added a link to groundwater depths
- Added a distance and area measuring tool
- Added a geologic map layer
- Updated the LS Factors with data from the SWRCB and added a LS layer to the map
November 2012
- Added a change log
- Added R factor information and links
- Increased the detail and zoom level for the LS layer
January 2013
- Changed the 303(d) list layers from KML to Fusion Tables to improve loading speed and performance
- Fixed the location or extent of many of the water bodies on the 303(d) list. These water bodies are: Arroyo Seco, Bear River Upper, Calleguas Creek, Chino Creek, Feather River South Fork, Fresno Slough, Lindero Creek, Los Angeles River, Mammoth Creek, Rio Hondo, San Gabriel River, San Luis Rey River, Santa Clara River, Yuba River South Fork
February 2013
- Added the following layers: Areas of Special Biological Significance, Caltrans Districts, Coastal Zone, Commercial Vehicle Enforcement Facilities, Counties, MS4 Areas, Erosivity Index Zones, R Factor, RWQCB Boundaries, and Vista Points
- Added a scroll bar to the layers list
January 2014
- Added the following to Caltrans facilities; agricultural inspection stations, equipment shops, offices, toll booths, and traffic management centers
- Updated the Watershed Boundary Dataset layer
February 2014
- Added the Postmile Lookup Tool
April 2014
- Added the search box to the map
- Added Caltrans tier 1 monitoring sites layer
- Updated ASBS outfalls layer
- Added additional help items
- User interface improvements
November 2015
- Updated the 303(d) list layer and tables to the 2012 list
- Added the arid and semi-arid regions layer
September 2016
- Added SWRCB K Factor layer
- Renamed Soil (K Factor) layer Soil Details
November 2016
- Added rainfall distribution layer
- Removed some Caltrans facility types
- Updated webpage template links
June 2018
- Updated the 303(d) list layer and tables to the 2014 - 2016 list
July 2019
- Increased the contrast of the 303(d) list and Water Quality Objectives Tables
- Added a tile, description, and purpose of the tool before the maps
- Increased the contrast of some layers
- Added CSV files for appropriate layers
- Updated links on the Help Page
- Added a "High Contrast” Google Maps style
May 2022
- Migrated the map and layers from Google Maps API to the ArcGIS Online API
- Added the 2020-2022 303(d) List
September 2022
- Added Flood Hazards Area layer
- Added Wetlands layer
- Added zoom to postmile button
- Added postmiles from Caltrans ArcGIS REST Server
- Added coordinates under the cursor to the botton left of the map
January 2023
- Added link to precipitation frequency data from NOAA Atlas 14
- Updated links
March 2023
- Updated links to the Construction General Permit and R Factor calculations
July 2023
- Updated accessibility assistance language
January 2024
- Added the 2024 303(d) List
May 2025
- Updated the High Risk Receiving Watershed Layer
- Updated the K Factor and LS Factor Layers
August 2025
- Added the R Factor Calculation Tool
For more information contact
Division of Environmental Analysis, Stormwater UnitCalifornia Department of Transportation
P.O. Box 942874, MS-27
Sacramento, CA 94274-0001
Email: