Post-Construction Program


The Post-Construction Program protects surface waters from the impacts of stormwater runoff after developments are constructed.  Please note that DEMLR also has a Sediment Program that applies to development activities during the construction process. 

Post-Construction Stormwater Map 

The Post-Construction Program applies to only certain parts of the state and is implemented by DEMLR in some areas and by local governments in other areas.  The Post-Construction Stormwater Map indicates if a post-construction program applies at any address in North Carolina. 

While we do our best to make the map as accurate as possible, this viewer is only a tool to help in making final determinations about your responsibilities for permit coverage. Please read the information below about using the results of this map viewer: 

For assistance with the interactive map, please contact Bethany Georgoulias.  

How to Rescind a Post-Construction Permit

To rescind a Post-Construction permit, submit a Permit Rescission Request Form to the appropriate DEMLR office.  Post-Construction permits may only be rescinded when the project will not be built as permitted or a local government has issued a Post-Construction permit covering a project that was already permitted by the Division.

How to Determine if a Project is High or Low Density

The Summary of Post-Construction Programs explains the various stormwater design requirements.  Most post-construction programs have a low and high density development option, the requirements for each option are codified in 15A NCAC 02H .1003.  

Low density projects must meet ALL of the following criteria:

  • Be designed with a built upon area (BUA) percentage below the threshold that pertains to the applicable stormwater program (see Chapter E-1 of the Stormwater Design Manual); 
  • Maximize dispersed flow through vegetated areas and minimize channelization of flow; AND
  • Transport stormwater that cannot be dispersed via vegetated conveyances (a small amount of piping is allowable for erosion control or driveway crossings when it cannot be avoided).

High density projects (projects that don't meet the low density criteria) must meet either the runoff treatment or volume match requirements (see Chapter A-1 of the Stormwater Design Manual).

  • Runoff treatment requires all of the stormwater generated from new BUA surfaces to be treated by a Primary Stormwater Control Measure (SCM).
  • Volume match is achieved by demonstrating that the annual runoff volume after development is no more than 10% higher than the annual runoff volume before development (5% in areas subject to SA waters requirements). 

For either high density option, projects that increase the BUA will need to implement structural SCMs. Each SCM must meet all of the General Minimum Design Criteria (MDC) in 15A NCAC 2H .1050 and the SCM-specific MDC in the appropriate section of 15A NCAC 02H .1051-.1062.  The Stormwater Design Manual provides guidance on how to meet the MDC.

The Department is working on replacement for the defunct “Storm-EZ” spreadsheet and improving the guidance in Part A-1 of the Manual for demonstrating that a project has met runoff volume match.