|Poorly maintained BMPs can result in significant quantities of sediment being discharged to storm drains.
Uncontrolled stormwater runoff from construction sites can significantly impact rivers, lakes and estuaries. Sediment in waterbodies from construction sites can reduce the amount of sunlight reaching aquatic plants, clog fish gills, smother aquatic habitat and spawning areas, and impede navigation.
Phase II MS4s are required to develop a program to reduce pollutants in stormwater runoff to the MS4 for construction sites disturbing one or more acres. This primarily includes developing:
- An ordinance,
- Requirements to implement erosion and sediment control best managment practices (BMPs),
- Requirements to control other waste at the construction site,
- Procedures for reviewing construction site plans,
- Procedures to receive and consider information submitted by the public, and
- Procedures for inspections and enforcement of stormwater requirements at construction sites.
In addition to the stormwater requirements that Phase II MS4s place on construction sites, construction operators must also apply for NPDES permit coverage if their project disturbs at least one acre and discharges to a waterbody. A description of these requirements is available at EPA's stormwater construction website.
Additional information on this minimum measure, including the stormwater Phase II regulatory requirements for construction site runoff control and a fact sheet on the construction minimum measure (PDF) (4 pp, 245 KB), is also available.
Key BMPs and Resources:
MS4s addressing the construction minimum measure should focus on the following four key BMPs to help them in developing a stormwater construction program.