Standardizing Cost Reporting in Municipal Stormwater Permits

The effective implementation of MS4 permits requires careful planning and dedicated resources from permittees, but permittees are rarely consistent in their approaches in estimating the costs of their stormwater programs due to a lack of standardized methodology for tracking and reporting permit related costs. This project will develop a water quality control policy for standardized reporting of costs associated with municipal stormwater permit implementation.

Project Contact Information

Project Lead:
(916) 327-5633

What's New

Project Description

Project Objective

This project will result in a State Policy for Water Quality Control for Standardized Cost Reporting in municipal separate storm sewer systems (MS4) permits (Policy). The proposed new Policy will require MS4 permittees to consistently estimate, track, and report costs that are directly related to MS4 permit implementation.


  • Review current MS4 permits, annual reports, and publicly available cost data to identify existing cost categories and compare reporting formats across permittees.  
  • Prepare draft standardized categories for reporting costs of MS4 Permit implementation.   
  • Perform case studies to validate proposed cost categories and reporting methods currently used by various permittees. 
  • Seek stakeholders’ input and finalize proposed cost categories (and sub-categories) based on said input.  
  • Develop tools for estimating, tracking, and reporting standardized MS4 permit implementation costs. 
  • Develop a statewide policy for standardized reporting of annual expenditures for MS4 permit implementation.


The California State Auditor’s Office (CSA) highlighted the need for standardized cost reporting guidance in a 2018 report titled “State and Regional Water Boards: They Must Do More to Ensure That Local Jurisdiction’s Costs to Reduce Storm Water Pollution Are Necessary and Appropriate.” CSA recommended that the State Water Board should develop statewide guidance on methods for tracking the cost of stormwater management, and that the Water Board should adopt regulations necessary to ensure regional boards and local jurisdictions follow its guidance. Based upon CSA’s recommendation, the Office of Research, Planning, and Performance (ORPP) published a guidance document for regional board’s staff (and the public) to obtain adequate, consistent, and comparable information regarding stormwater management costs related to the Phase I MS4 permit. As an extension of this prior effort, STORMS staff were tasked in 2020 to develop a regulatory approach to establish standardized cost reporting requirements for estimating, tracking, and reporting MS4 permit compliance costs.