Stormwater Overview
SCDES manages South Carolina's Stormwater Program
Who needs a stormwater permit?
- All construction sites of 1 acre or more
- Many industrial sites
- All regulated Municipal Separate Storm Sewer Systems (MS4s) .
Some sites can obtain permit coverage under the state general permit, but sites that pose considerable risk to contaminate water may be required to obtain an individual permit (a longer, more involved process).
SCDES's Stormwater Permitting Section issues permit coverage for the above activities as part of SCDES's wider NPDES (National Pollutant Discharge Elimination System) Permitting Program .
NPDES Permit Program
NPDES is a regulatory program created under the Clean Water Act, and it is one of the main driving forces behind the majority of the mandated state and federal regulations.
Under the NPDES Permit Program, stormwater discharges are considered point sources and operators of these sources are required to receive an NPDES permit before they can discharge stormwater runoff.
This NPDES Program as it relates to stormwater management was designed to be a phased control approach that begun in 1990. The EPA has successfully implemented Phase I and Phase II of this program (see below) and any new or modified regulations must go through a rulemaking process that includes a proposal, public comment, and then culminating with a final rule that must then be implemented and enforced. In addition to the above, the EPA has granted authority to allow states to implement the NPDES stormwater program.
Phase I (1990)
| Construction Activities | Required all construction sites disturbing 5 or more acres to obtain coverage to discharge stormwater under the NPDES Program. |
|---|---|
| Industrial Activities | Defined 11 categories of industrial activity (including construction) if disturbance of activity is equal to 5 acres or more than NPDES approval was required. |
| MS4s | Required all municipalities with populations equal to 100,000 or more to acquire coverage for NPS discharge under the NPDES Program. |
Phase II (March 2003)
| Construction Activities | Required all construction sites disturbing 1-5 acres to acquire coverage under NPDES program. |
|---|---|
| Industrial Activities | Added 1-5 acres in Industrial activities and expanded upon the no exposure limitation from 1 group of activity to all 11 groups. |
| MS4s | Required municipalities with populations between 10,000 and 100,000 to obtain NPDES Coverage. |