Technical Guidance Manual for Stormwater Quality Measures – New Development and Redevelopment Projects (TGM)

This page is to communicate information on the revisions to Technical Guidance Manual for Stormwater Control Measures. If you would like to be notified by email when this page is updated, please send a request to David Laak (David.Laak@ventura.org) with “TGM Stakeholder Email” in the subject line.

[NEW] TGM 2025

This Technical Guidance Manual for Stormwater Quality Control Measures (2025 TGM) provides guidance for the implementation of stormwater management control measures in new development and redevelopment projects located in the County of Ventura and the incorporated cities therein. These guidelines have been developed to meet the Planning and Land Development requirements contained in the regional Phase I Municipal Separate Storm Sewer System (MS4) National Pollutant Discharge Elimination System (NPDES) Permit for stormwater and non-stormwater discharges from the MS4 within the coastal watersheds of Los Angeles and Ventura Counties (CAS004004, Order No. R4-2021-0105), henceforth referred to in this document as the 2021 MS4 Permit.

2025 TGM
2025 TGM Tool – An updated electronic tool to assist land development project applicants in meeting the new LID requirements under the new Permit. [To ensure you use the correct version of this tool always check with the agency that has jurisdiction over your project before starting. Links are provided at the bottom of this page.]

2025 TGM BMP Sizing Worksheets:

TGM Errata Update 2018 Version

The 2015 TGM Errata Update was updated in 2018 to correct minor errors and unintentional omissions. Due to the evolving nature of stormwater quality management, the TGM may continue to be updated to correct errors, to incorporate new and innovative control measures, or to add the Hydromodification Control Plan.

Errata Update TGM (June 2018)
2018 Errata Update Summary
2018 TGM Tool – An updated electronic tool to assist land development project applicants in meeting the new LID requirements under the new Permit. [To ensure you use the correct version of this tool always check with the agency that has jurisdiction over your project before starting. Links are provided at the bottom of this page.]

TGM Errata Update 2015 Version

The 2011 TGM was updated in 2015 to correct minor errors and unintentional omissions. Due to the evolving nature of stormwater quality management, the 2011 TGM may continue to be updated to correct errors, to incorporate new and innovative control measures, or to add the Hydromodification Control Plan.

The Technical Guidance Manual was approved by the Executive Officer of the LA Regional Board on July 13, 2011. The new rules became effective on October 11, 2011. For more information on how the effective date applies to projects see page 1-8 of the TGM.