Hydraulics and Stormwater


Effective Hydraulics and Stormwater Design emphasizes stewardship of California's water resources by providing:

  • Development and maintenance of guidance and state-of-the-practice information for departmental staff to promote uniformity and consistency in the design of roadway drainage-related features.
  • Technical assistance to designers on unique or unusual drainage design issues.
  • Liaison to industry, Federal Highway Administration (FHWA), and other interested external entities for roadway drainage product approvals, processes, and requirements.
  • Technical assistance to designers on stormwater pollution control implementation.
  • Assistance to designers to assure compliance with Caltrans' statewide National Pollutant Discharge Elimination System (NPDES) permit.
  • Guidance and training for the implementation of appropriate Storm Water Best Management Practices (BMPs).
  • Management and performance of drainage related special studies and research activities.
  • Development and oversight of drainage-related training courses.
  • Development and maintenance of Roadway Drainage Standard Plans and Specifications.

Hydrology and Drainage Information

Alternative Pipe (AltPipe) Culvert

Authorized Materials List

  • Authorization Criteria for Cementitious Materials for Pipeliners and Invert Paving (PDF)
  • AML Cementitious Pipeliners and Concrete Invert Paving (PDF)
  • Authorization Criteria for Grated Line Drain (PDF)
  • AML Grated Line Drain (PDF)

Bank and Shore Rock Slope Protection Design

  • Highway Design Manual (HDM) Chapter 870: Bank Protection - Erosion Control
    • This can be a major element in the design, construction and maintenance of highways.
    • Section 870 deals with procedures, methods, devices and materials commonly used to mitigate the damaging effects of flowing water on transportation facilities and adjacent properties.
    • Potential sites for such measures should be reviewed in conjunction with other features of the project such as long and short term protection of downstream water quality quality, aesthetic compatibility with surrounding environment, and ability of the newly-created ecological system to survive with minimal maintenance.
    • See Index 110.2 for further information on water quality and environmental concerns related to erosion control.
    • See Chapter 880 for shore protection along coastal zones and lake shores that are subjected to wave attack.
    • Also refer to the Standard Specifications Section 72 for RSP Rock Class.
  • Highway Design Manual (HDM) Chapter: 880 Shore Protection
    • Shore protection along coastal zones and lake shores that are subjected to wave attach can be a major element in the design, construction and maintenance of highways.
    • This chapter deals with procedures, methods, devices and materials commonly used to mitigate the damaging effects of wave action on transportation facilities and adjacent properties.
    • The primary focus is on quantifying exposure of these locations to sea level rise, storm surge and wave action.
    • The practice of coastal engineering is still much of an art.
    • This is for a variety of reasons including that the physical processes are so complex, often too complex for adequate theoretical description, and the design level of risk is often high.
    • Also refer to the Standard Specifications Section 72 for RSP Rock Class.

Gabion Mesh Corrosion

  • Gabion Mesh Corrosion Field Study of Test Panels and Full-scale Facilities (November 2001) (PDF)
    • This second edition of the final research report was intended for distribution as a paperless report.
    • All of the conclusions and all of the recommendations in the November 2001 and May 2001 editions are identical.
    • For general guidance, see:
      • Conclusions (last paragraph of page 99 and all of page 100)
      • Recommendations (pages 101 through 105)
      • Appendix (pages 110 and 126).
    • Owners of the first edition (May 2001) (PDF) should replace pages 16, 56, and 107. The cover, signature, and Technical Report Documentation pages were changed to reflect the November 2001 date. A few other pages have minor corrections. All of the photos were darkened to improve the images.
    • Printed (hard-copy) reports are not available from Caltrans.

Stormwater Information

Best Management Practices (BMPs)

Click Here to Launch the Treatment BMPs Application Tool

  • Note: This tool is only viewable using Microsoft Internet Explorer

Construction Site BMPs - Specifications, Standard Plans and Guidance

Procedure for Specification Sponsor Concurrence

  • The Caltrans Office of Hydraulics and Stormwater Design is the sponsor for water pollution control and temporary construction site BMP special provisions. Any proposed new specifications or significant modifications to the following must be reviewed by the Office of Hydraulics and Stormwater Design for concurrence. Please follow the sponsor request and concurrence process for non-standard special provisions (nSSPs).
  • In order for Office of Hydraulics and Stormwater Design to review and approve the use of the Treatment BMP (TBMP) nSSPs, a complete BMP package is required, which includes the following:
  1. Request Memo - Follow the procedures outlined above.
  2. nSSPs - Download the latest Treatment BMP nSSPs on Treatment BMPs Webpage.
  3. This website link (see item 2 above) also includes a Design Guidance for each TBMP. Read the document prior to and during the design process and follow the recommended procedures.
  4. This website link (see item 2 above) also includes TBMP plans. Use the PDF plans until ready to submit to OE. Then,use the TIF plans. No changes to the Caltrans plans are allowed. Read the design guidance if changes must be made.
  5. This website link (see item 2 above) also includes a design spreadsheet for AVSFs and GSRDs (Inclined Screen only). Use this spreadsheet for each designed and submit an electronic copy to your email. Make sure that the last tab on the AVSF spreadsheet, which is for cost estimating, is filled out with the same unit and unit price for each TBMP item as BEES.
  6. Send an electronic PDF copy of plan sheets that pertain to the nSSPs (include cover sheet, layouts, drainage plans and profiles, detail sheets, quantity sheets, and nSSP plan sheets that will be submitted to OE, etc.) Do not send a copy of all sheets for project.
  7. BEES (only the items that relate to the nSSPs) - Send an electronic pdf copy.
  8. NOTE: As part of the email submission package, include milestone dates and critical dates of the project.

Device Modifications


Construction BMP Cost Estimator

  • The Construction BMP Cost Estimator is used to help prepare information for Construction Division concurrence submittal. The North Region developed this spreadsheet, and other districts are encouraged to use it.

Pervious Pavement

  • The guidance and specifications being provided are the result of collaboration between members of the pervious pavement team that included various HQ Functions and Industry.
  • The goal of developing this guidance was to have consistent methods, siting criteria, and material specification, when considering the use of pervious pavement within Caltrans right of way.
  • Caltrans now has the ability to install this type of stormwater feature.
  • Currently pervious pavement can only be considered within Caltrans right of way at non-highway facilities (Rest Areas, Park and Rides, etc.) including Maintenance Vehicle Pullouts on highway facilities.
  • As described in the guidance, approval from HQ Hydraulics and Stormwater Design and HQ Maintenance is required before pervious pavement can be included in a contract or constructed within Caltrans right of way.
  • By requiring these approvals (gate keeper approach), an evaluation can occur related to appropriate feasibility and maintainability.
  • When a location is approved for use, it will be tracked similar to a pilot project to evaluate construction methods (potential specification improvements) and maintainability (to assure that proposed maintenance procedures will be adequate).
  • When pervious pavement is being proposed as a viable BMP the Pervious Pavement Design Guidance will provide the consistency needed for an appropriate evaluation.
  • Pervious Pavement Guidance and Tools:
    • Caltrans Stormwater Quality Handbook: Pervious Pavement Guidance
    • Specifications (Zip File)
    • Reservoir Design Tool


Design Guidance

Treatment BMPs (Plans, Specifications, and Guidance)

Construction Site BMPs Design Guidance

Construction General Permits (CGP)

Rainfall Erosivity

  • Rainfall Erosivity Guidance
  • Waiver Form CEM2005
  • Erosivity Waiver Order of Work

Erosion Prediction with RUSLE2 (HTML)

Fact Sheets


Project Planning and Design Guide (PPDG)

  • In 2013, the State Water Resources Control Board (SWRCB) issued a National Pollutant Discharge Elimination System (NPDES) permit that regulates stormwater discharges from Caltrans facilities.
    • This permit requires Caltrans to maintain and implement an effective Stormwater Management Plan (SWMP) that identifies and describes the Best Management Practices (BMPs) used to control the discharge of pollutants to waters of the United States.
  • The PPDG describes the process for Caltrans staff to incorporate the BMPs from the SWMP into the planning and design phases of a project.
    • It is important to note that this guide provides only minimum guidelines, and that Stormwater controls other than what are included may need to be incorporated on a project-by-project basis to comply with special requirements from a Regional Water Quality Control Board.
  • The PPG may be updated as needed to reflect changes to the SWMP.

Studies & Report (HTML)

Storm Water Data Reports (SWDR)

  • SWDRs are required at all project phases.
  • The current SWDR Forms and their applicability are listed below:
    • Micro SWDR forms may be utilized for projects without stormwater impacts at any project phase.
    • PID SWDR forms (aka Interim PID (PIR) SWDR) may be utilized in place of Long Form SWDRs or Short Form SWDRs at the project PID phase.
    • Long Form SWDRs are required at the PAED and PSE phase for projects that require treatment BMPs, have potential water quality impacts, or plan to obtain Compliance Unit credits.
      • Projects in these categories not utilizing the PID SWDR form must also prepare a Long Form SWDR at the project PID phase.
    • Short Form SWDRs are required at PAED and PSE phase for projects that do not meet the requirement of the Long Form SWDRs.
      • Projects in these categories not utilizing the PID SWDR form must also prepare a Short Form SWDR at the project PID phase.
    • All of the above mentioned forms are available to be downloaded below.
  • Consult your local Design Stormwater Coordinator for more information about the appropriate stormwater document for your project.
  • Micro SWDR (HTML)
  • Interim PID (PIR) SWDR (HTML)
  • Files & Attachments (HTML)



  • T1 Checklist - Infiltration Tool
    • T1 Infiltration Tool
    • How Fields D19, 20, and 21 for Infiltration Tool v3 (IT v3) should be filled in to use with the 2012 Permit (PDF)
    • Guidance (PDF)
    • T-1 Infiltration Tools Presentation (May 10, 2013) (PPTX)
  • Risk Level Determination - Topography Tool (HTML)
  • Caltrans RUSLE2 (HTML)
  • Water Quality Planning Tool
  • Basin Sizer


    Fish Passage Design for Road Crossings Manual

    Highway Design Manual - Hydraulics and Stormwater Related Chapters

    • General Aspects - Chapter 800 (PDF)
    • Hydrology - Chapter 810 (PDF)
    • Cross Drainage - Chapter 820 (PDF)
    • Transportation Facility Drainage - Chapter 830 (PDF)
    • Subsurface Drainage - Chapter 840 (PDF)
    • Physical Standards - Chapter 850 (PDF)
    • Open Channels - Chapter 860 (PDF)
    • Bank Protection - Erosion Control - Chapter 870 (PDF)
    • Shore Protection - Chapter 880 (PDF)
    • Storm Water Management - Chapter 890 (PDF)