The STEPP program is currently accepting applications for trash capture technologies for STEPP verification as well as hydrodynamic separator (HDS) technologies for both STEPP verification and for concurrence verification. For more information on these services, see below.
STEPP Verifications
STEPP verifications are those verifications for which STEPP provides full evaluation, oversight and third-party review services. This process is a review of the verification application followed by a third-party review of the quality assurance project plan (QAPP) and a public review and third-party review of the lab testing report after testing is complete to ensure that testing was performed in accordance with ASTM standards.
Lab Concurrence Verifications for Hydrodynamic Separator (HDS) Systems
Lab concurrence verifications is an effort by STEPP to review the verification documents based upon previous lab-based testing verification programs. Concurrence verifications by STEPP are limited to those previous verifications that used testing standards and protocols consistent with ASTM standards and STEPP policies and procedures. Currently, concurrence verifications are limited to HDS systems.
More Information and Getting Things Started
Please see STEPP documents (see links below) for detailed information. To initiate a verification, download the STEPP Lab Testing Verification Application or the STEPP Lab Testing Hydrodynamic Separator Concurrence Verification Application document, fill out and email to Seth Brown, STEPP Director, at seth.brown@nationalstormwateralliance.org.
STEPP Program Documents
- STEPP Lab Testing Verification Documents
- STEPP Lab Testing Concurrence Verification Documents
Ongoing Hydrodynamic Concurrence Reviews
- None
Completed Hydrodynamic Concurrence Verifications
- Arcadia Hydrodynamic Separator, Advanced Drainage Systems, Inc.
Ongoing Trash Capture Device STEPP Verifications
- StormTrap TrashTrap - Application accepted, QAPP reviewed and approved, Lab Testing Evaluation Report being reviewed
- EnviroPod LittaTrap - Application accepted, QAPP pending
- Oldcastle Infrastructure Nutrient Separating Baffle Box - Application accepted, QAPP reviewed and approved, Lab testing ongoing
Completed Trash Capture Device STEPP Verifications
- None
Ongoing Hydrodynamic Separator STEPP Verifications
- None
Completed Hydrodynamic Separator STEPP Verifications
- None
The STEPP program provides value to a variety of stakeholder, including regulators, municipalities, manufacturers of stormwater technologies and treatment devices (MTDs), environmental NGOs, researchers, stormwater practitioners and consultants, land development groups, and others. This paper authored by David Smith, formerly with EPA Region 9 and a current NMSA Emeritus Member, articulates the specifics on this value of STEPP for the various stakeholders identified.
STEPP has received letters of support from many groups spanning this range of stakeholders, including those listed below. If your organization is interested in expressing support for STEPP, please use this template and send the completed letter on your organization's letterhead to Seth Brown, NMSA Executive Director at seth.brown@nationalstormwateralliance.org.
- New Jersey Department of Environment Protection
- Washington Department of Ecology
- American Public Works Association, Washington State Chapter
- Michigan Department of Environment, Great Lakes, and Energy (formerly the Department of Environment Quality)
- National Association of Home Builders
- Associated General Contractors of America
- International Council of Shopping Centers
- Leading Building of America
- National Apartment Association
- National Multifamily Housing Council
- National Association of Realtors
- Retail Industry Leaders Association
Communities or groups of communities who want to become members of the STEPP program can join online by clicking here and selecting either the Individual MS4 NMSA Membership option (only option available to Phase I and DOTs) or the Group MS4 NMSA Membership option (only available for Phase IIs and Non-traditional MS4s). If you are an organization that tests, manufacturers, distributes/resells, constructs/installs, or are otherwise associated with stormwater products and practices, and you want to join NMSA or STEPP, please contact Seth Brown, STEPP Director, at seth.brown@nationalstormwateralliance.org. For organizations that focus on research, consulting, legal support or similar services click here and review the Affiliate Membership option.
To learn more about NMSA, please go to our website: https://ms4nmsa.org/.
STEPP Membership Benefits
- Understand the value of performance for all stormwater infrastructure, both proprietary products and public domain practices.
- Gain access to all available STEPP verification data and documents.
- Be eligible to access technical guidance and training on how to interpret, understand and apply/integrate STEPP verified data in your stormwater program.
- Be eligible to serve in key elements of STEPP program governance bodies, such as the STEPP Stakeholder Subcommittee.
- Receive regular updates on the STEPP program including new products and services available to STEPP members.
To provide transparency, the STEPP verification process includes a public review. The specifics of this information are provided in the STEPP Public Review Overview Document. Public review comments must be provided using the STEPP Public Review Comment Form. Failure to follow the directions in the STEPP Public Review Overview Document will result in automatic exclusion of submitted comments. STEPP Public Reviews are intended to be as inclusive as possible and all efforts are made to broadcast information about active reviews based upon a database of interested stakeholders.
Public Review Overview
The STEPP Public Review Process is to allow interested parties to provide comments on technical and procedural aspects of performance testing campaigns. STEPP reserves the right to dismiss comments that are off topic (i.e., outside of technical and procedural aspects of testing campaigns) and/or are not provided in good faith.
Current Public Reviews
There are no public reviews currently active.
Get Involved
If you wish to be added to this database, please use the form on this page or email Seth Brown, STEPP Director, at seth.brown@nationalstormwateralliance.org.
STEPP Public Reviews
By leading the development of performance testing procedures and standards, providing technical review and oversight of testing/evaluation performed using these standards, and developing and disseminating contextual information on the results of these evaluations to state regulators and local NPDES (MS4, etc.) permit holders, the STEPP program seeks to raise the level of performance for stormwater programs overall.
STEPP, being an Environmental Technology Verification (ETV) program tailored to the stormwater sector, has a framework consistent with ETVs in other sectors. The construct of ETVs are generally defined consistently with the framework spelled out in the international standard ISO 14034. The elements comprising an ETV includes:
- Application - STEPP staff reviews application information to ensure that the product or practice submitted by the technology proponent can be verified by STEPP.
- Testing Plan - STEPP spells out the testing campaign requirements and recommendations in a Quality Assurance Project Plan (QAPP) document that provides technology proponents with the best information available to perform a successful testing campaign.
- Testing Campaign - STEPP does not perform testing, but staff can work with proponents to identify testing facilities that can perform the testing services consistent with ASTM testing standards.
- Performance Verification - Once the testing campaign is completed, STEPP staff and third-party reviewers from the roster of highly-qualified professionals referred to as the "STEPP External Review Group" review the test report focused on consistency with ASTM performance testing standards. There is also a public review integrated into the STEPP verification process.
- Verification Documentation - STEPP provides a summary of findings and verified performance test results in the context of the performance claim provided and summarizes this information in verification letter and report.
A critical component of the program is the STEPP External Review Group (SERG), which is a roster of stormwater professionals who work with STEPP staff to review and evaluate testing information. SERG members are selected by the STEPP program administrator based on their proven credentials in stormwater management research and include top-tier level academics from across the country. This roster of reviewers provides objective and highly qualified input on all verification efforts. The size and composition of the SERG roster is likely to evolve along with the changes in the STEPP program, including activities such as field-based verifications, potentially new technologies and pollutants of interest to be integrated into the program, and the inclusion of public domain practices in the context of STEPP verification services offered.
The 2026 SERG roster is:
- Jim Lenhart, Stormwater Northwest
- Andy Erickson, PhD, PE (University of Minnesota)
- Celso Ferreira, PhD, PE (George Mason University)
- Dipen Patel, PhD (Sacramento State University)
- Jon Hathaway, PhD (University of Tennessee)
- Bruce Thomson, PhD (University of New Mexico)
- Elizabeth Fassman-Beck, PhD (Southern California Coastal Water Research Project)
- Ryan Winston, PhD (Ohio State University)
- Allen Davis, PhD (University of Maryland)
- David Sample, PhD (Virginia Tech)
- Jason Vogel, PhD (University of Oklahoma)
- Dwane Jones, PhD (University of the District of Columbia)
- David Spelman, PhD (Bradley University)
- Sybil Sharvelle, PhD (Colorado State University)
A fundamental principle of the STEPP program is that all stormwater infrastructure should be evaluated in a consistent, credible and robust manner to better understand the performance of stormwater control measures regardless of if they are proprietary in nature or a public-domain practice. Stemming from this principle, STEPP will provide testing and verification services to any and all SCMs. Currently, STEPP is limited to testing trash/debris capture technologies and hydrodynamic separators, which are categories of proprietary SCMs. Future and ongoing efforts will broaden the scope of STEPP to include additional proprietary products as well as public domain practices.
The STEPP program exclusively relies on ASTM standards as the technical basis for performance testing of SCMs. The basis for this reliance is due to the broad reach of acceptance of ASTM standards across the U.S. and beyond. Additionally, ASTM standards are used regularly by engineers and scientists in public works departments and within stormwater programs to enumerate methods for construction, assessments, and other technical activities led by stormwater professionals. ASTM E64 Committee on Stormwater Control Measures is the primary body within ASTM that is the technical bridge to STEPP, however other ASTM committees are pertinent in the context of STEPP, such as C27.70 Subcommittee on Precast Concrete Products for Stormwater Management and E60 Committee on Sustainability.
Catalyzing the established E64, a new ASTM committee focused wholly on stormwater infrastructure.
Facilitating the completion of ASTM field testing standards.
Completed ASTM lab testing standards for trash capture technologies and hydrodynamic separator systems and making significant progress in developing lab testing standards for filter technologies.
Offering lab-based verification services for trash capture technologies and hydrodynamic separator systems.
Offering lab-based concurrence verification services for hydrodynamic separator systems that has been previously reviewed by another verification entity if the performance testing standards are consistent with ASTM standards.