Information provided for reference purposes only

Note: This information is provided for reference purposes only. Although the information provided here was accurate and current when first created, it is now outdated. All the links in the document have been removed.


NPDES Storm Water Program for Construction Activity Disturbing Less Than 5 Acres 

Under the Storm Water Phase II Final Rule, construction activity disturbing equal to or greater than one acre and less than five acres of land is subject to NPDES permitting requirements.  Construction activity disturbing less than one acre requires a permit if it is part of a larger common plan of development or sale disturbing a total of one acre or greater, or is individually designated for permit coverage by the NPDES permitting authority.  The NPDES Storm Water Program currently addresses storm water discharges from construction sites disturbing five acres or greater (as well as sites less than five acres if they are part of a larger common plan of development or sale disturbing a total of  five acres or greater).

IMPORTANT: Note that permit applications from operators of constructions activities disturbing less than five acres will not be due until 2002/early 2003. Contact your Permitting Authority for the exact date.

Key questions addressed here include:

  • What is required of Phase II construction operators under the Final Rule?
  • What waivers are available for Phase II construction activity?


  • Storm Water Phase II Final Rule: Construction Program Overview (Fact Sheet 3.0)
  • Storm Water Phase II Final Rule


What Is Required Of Phase II Construction Operators Under The Final Rule?

The Phase II Final Rule requires, nationally, operators of Phase II construction sites to obtain an NPDES permit and implement best management practices (BMPs) to minimize pollutant runoff. [It is important to note that, locally, these same sites may also be covered by State, Tribal, or local construction runoff control programs.] For the Phase II construction program, EPA has taken an approach similar to the current Phase I approach where the program requirements are not fully defined in the rule but rather in the NPDES storm water permit issued by the NPDES permitting authority. EPA recommends that the NPDES permitting authorities use their existing NPDES storm water general permits for construction as a guide in developing their Phase II construction permits. In doing so, the Phase II requirements will be similar to the following three main requirements of EPA's Construction General Permits:

  • Submission of a Notice of Intent (NOI) that includes general operator and site information, and a certification that the activity will not impact endangered or threatened species. This certification is unique to EPA’s NOI and is not a requirement of most NPDES-delegated State’s NOIs;
  • The development and implementation of a Storm Water Pollution Prevention Plan (SWPPP) with appropriate BMPs to minimize the discharge of pollutants from the site; and
  • Submission of a Notice of Termination (NOT) when final stabilization of the site has been achieved as defined in the permit, or storm water runoff is no longer being discharged, or when another operator has assumed control of the site.  

What Waivers Are Available for Phase II Construction Activity?

Under the Phase II Final Rule, NPDES permitting authorities have the option of providing a waiver from the requirements to operators of Phase II construction activity who could certify to one of two conditions:

  1. Low predicted rainfall potential (i.e., activity occurs during a negligible rainfall period), where the rainfall erosivity factor ("R" in the Revised Universal Soil Loss Equation (RUSLE)) is less than 5 during the period of construction activity. Chapter 2 of the USDA's publication, "Predicting Soil Erosion by Water: A Guide to Conservation Planning with the Revised Universal Soil Loss Equation (RUSLE)", is now available for download here (in Adobe Acrobat format) and contains more information on the R factor. Fact Sheet 3.1 on the "Construction Rainfall Erosivity Waiver" will be availabe soon - see the Fact Sheet series for this and other fact sheets on the Phase II program.

  2. A determination that storm water controls are not necessary based on either:

(A) Total Maximum Daily Load (TMDL) approved or established by EPA that addresses the pollutant(s) of concern for construction activities; or

(B) For non-impaired waters that do not require TMDLs, an equivalent analysis that determines allocations for small construction sites for the pollutant(s) of concern or that determines that such allocations are not needed to protect water quality based on consideration of existing in-stream concentrations, expected growth in pollutant contributions from all sources, and a margin of safety.

Note: Waivers are not available for any construction activity disturbing 5 acres or greater, or less than 5 acres if part of a common plan of development or sale (or if designated for permit coverage by the NPDES permitting authority).


Disclaimer: The information contained on these pages is a general statement of policy. It does not establish or affect legal rights or obligations. It does not establish a binding norm and is not finally determinative of the issues addressed. Agency decisions in any particular case will be made by applying the law and regulations to the specific facts of the case. This applies to all pages in the NPDES Storm Water Program web hierarchy (