Permitting Green Infrastructure: A guide to improving municipal stormwater permits and protecting water quality

Permitting Green Infrastructure provides information about sustainable and adaptive trends in stormwater permitting with examples of stormwater permits that encourage or require low impact development or green infrastructure. While useful to the professional community, the guide is intended to be a resource for community and watershed advocates. 

The report offers a short history of the Clean Water Act’s stormwater provisions, the federal and state permitting programs authorized by those provisions, and a newer generation of regulatory approaches and from water advocacy organizations, stormwater professionals and permitting agencies.  

The guide is primarily a comparison of several different permitting approaches to requiring or supporting green infrastructure responses to stormwater discharges from new development or redevelopment projects. Relevant portions of Municipal Separate Storm Sewer System (MS4) permits have been selected from current or draft permits for demonstration. Additionally, the permit language that ties specific performance standards for redevelopment projects to credits or incentives that encourage smart growth approaches are highlighted. The report includes excerpts from comment letters written by local watershed advocates that have helped to drive this process. In terms of organization, it’s intended to be a “matrix,” linking each example of a permitting approach to a comment letter that addresses the some aspect of that approach.

The first part of the Matrix provides excerpts from MS4 permits with green infrastructure components, that reflect the categories EPA outlined in its Permit Improvement Manual:

1. Objective performance standard that control volume and mimic pre-development hydrology

2. Explicit requirements for green infrastructure measures

3. Limits or ceilings on the amount of effective impervious area

The permits described here set objective performance standards for on-site stormwater management, explicitly calling for green infrastructure practices, or, less frequently, establishing limits on the effective impervious area created by development projects. Examples from each category are provided, illustrating the differences that individual states have taken to respond to local concerns, capacities, and water quality drivers.

The primary permits types reviewed include: 

- Percentile Storm Standard, Specified Green Infrastructure Practices, and Hydromodification Protections

- Standard Based on Percentile Storm, Comparable to E.I.S.A. Section 438

- Objective Performance Standard Expressed as a Measured Level of Precipitation

- Narrative Performance Goal with a Preference for Green Infrastructure



American Rivers is a non-profit organization established in 1973 to protect wild rivers, restore damaged rivers, and conserve clean water for people and nature. They combine national advocacy with field work in key river basins by building partnerships and working closely with local river advocates, business and agriculture interests, recreation groups and others to forge solutions.


Publication Date: January 2013

Author or Affiliated User:

  • Jeffrey Odefey

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Resource Category:

Resource Types:

  • Best practice
  • Legal Analysis


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