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Nutrient Practices and Crediting

Nutrient Practices and Crediting


A variety of practices to reduce nutrient loading to surface waters are approved by the Division. These nutrient reduction practices, which include design criteria and credit calculation methods, are available for use toward compliance with requirements of new or existing development stormwater rules, as well as for generating nutrient reduction credits for trading or offset. They supplement the growing set of stormwater control measures (SCMs) approved by the Division of Energy, Mineral and Land Resources for new development post-construction runoff treatment. Developers can also buy nutrient offset credits from the NC Division of Mitigation Services (DMS) or from private providers approved by the Division of Water Resources (DWR) to meet some of their nutrient reduction requirements.

On this webpage, you can find information regarding the following:

Stormwater Nutrient Accounting Tools

SNAP (Stormwater Nitorgen and Phospohorus) v4.0 is a nutrient accounting tool descended from the Jordan/Falls Lake Stormwater Nutrient Load Accounting Tool v2.0.  Below is a draft version of the tool which we are requesting comments on - please send those to Trish D'Arconte ( This tool estimates runoff nutrient loads from developed lands and load reduction benefits for the large set of Stormwater Control Measures that follow DEMLR's new Minimum Design Criteria. 

If you have questions about using SNAP you can post them to the SNAP Users Listserv, or send your questions directly to Trish D’Arconte ( ). To subscribe to the listserv, send an email to with only the word “subscribe” in the subject or body of the email. Make sure to check your Junk Mail box for the subscription confirmation email.

Rules concerning new development in the Neuse and Tar-Pamlico watersheds continue to require the use of older methods. Developments in the Tar-Pamlico watershed should calculate nutrient export and treatment with the Tar-Pamlico Piedmont and Coastal Plain Export Calculation Worksheets .

Developments in the Neuse watershed outside of the Falls Lake watershed should continue to use the calculation method laid out in the Neuse Model Program .

DMS has received approval from DWR to use the SNAP Tool for generating buffer mitigation credits in accordance with 15A NCAC 02B .0295(o)(9),  as noted in the above approval memo.

Approved Nutrient Reduction Practices

Nutrient credits may be generated to meet Existing Development Stormwater rule requirements through either retrofitting of existing developed lands using the SCMs and accounting described above or implementation of other approved nutrient reduction practices. Below are documents describing design specifications and nutrient accounting for other types of nutrient reduction practices that are approved by the Division as of September 2017.

About Nutrient Offsets and Trading

Nutrient offset is a form of trading allowed by the Division of Water Resources under each set of rules governing the four Nutrient Management Strategy watersheds in NC. Other forms of trading are also allowed as provided for within the different strategies’ rules. Effective September 2010, 15A NCAC 02B .0240 addresses procedural requirements for nutrient offsets, including geographic scope, project standards, payment conditions, and other issues.

Developers, wastewater treatment facilities, and others can often meet a portion of their nutrient reduction requirements by purchasing nutrient offset credits. These credits are generated by riparian restoration/enhancement projects constructed elsewhere within the watershed, either by private mitigation providers  or the NC Division of Mitigation Services (DMS). 

The predominant nutrient reduction practice used by those seeking to generate nutrient reduction credits for sale is the restoration and enhancement of riparian forested buffers on agricultural lands. The Division allows the use of forested buffer restoration and enhancement as described in 15A NCAC 02B .0295(n)(2-4) to award a nutrient reduction benefit of 75.7 lbs/yr nitrogen and 4.88 lbs/yr phosphorus. Such projects must meet design criteria.

Other practices are also eligible to generate nutrient reduction credit for sale (e.g., stormwater control measures), but to date, these have not been as cost-effective as buffer restoration.

Developers seeking nutrient offset credits should first consult with their local government permitting authority for routine inquiries. Requests for nutrient offset credits require the submission of a form approved by the local government. Users of the SNAP Tool can generate a generic nutrient offset request form within SNAP. Developers in the Neuse (outside Falls) and Tar-Pamlico watersheds have a different form to use .

For additional questions regarding this topic, please contact DEQ representatives as directed below.


For questions regarding nutrient offset credit purchases, please contact your local government permitting representative. Additional inquiries regarding nutrient offset or trading may be directed to: Jim Hawhee, Environmental Program Consultant, 919-807-6439 or

For questions regarding nutrient accounting tools and reduction practices, please contact: Trish D’Arconte, Environmental Program Consultant, 919-807-6439 or

For questions regarding private nutrient mitigation providers please contact: Katie Merritt, Nutrient Offset Banking Coordinator, 919-807-6371 or .

For questions about nutrient credit purchases from the NC Division of Mitigation Service's In-lieu Fee Program, please contact: Kelly Williams, NCDMS In-Lieu Fee Program Coordinator, 919-707-8915 or