Stormwater regulations for construction sites are environmental mandates designed to control runoff, prevent soil erosion, and keep pollutants out of local waterways.
Under the federal Clean Water Act’s National Pollutant Discharge Elimination System (NPDES), these rules require any project disturbing one or more acres of land to obtain permit coverage before starting work.
Compliance typically involves implementing a comprehensive Stormwater Pollution Prevention Plan (SWPPP), managing runoff controls, and conducting regular site inspections to avoid costly civil and criminal penalties.
In this guide, you’ll learn what developers, contractors, and site managers need to know to navigate stormwater compliance, understand federal and state permit requirements, and avoid costly enforcement actions.
Failure to comply can carry civil penalties of up to $25,000 per day, per violation, under Section 309 of the Clean Water Act. Regulators can also seek criminal penalties for willful or negligent violations.
Understanding the Clean Water Act and the NPDES Program
All U.S. stormwater regulations originate from the Clean Water Act of 1972. This act specifically prohibits the discharge of pollutants from a point source to waters of the United States without a permit.
In 1987, Congress amended the CWA to explicitly cover stormwater discharges and directed the EPA to develop a permit framework for stormwater from construction sites, industrial facilities, and municipal separate storm sewer systems (MS4s).
The EPA implemented those requirements through the NPDES stormwater regulations, first published in 1990 and significantly expanded in 1992 and 1999. The current regulatory framework requires:
- Phase I coverage: All construction sites disturbing five or more acres, plus sites of any size that the permitting authority determines to be a significant contributor of pollutants to waters of the United States.
- Phase II coverage: All construction sites disturbing one or more acres or less than one acre when part of a common plan of development or sale that will ultimately disturb one or more acres.
The one-acre threshold applies to total disturbed acreage across the project life, not the area disturbed at any single point in time. A project that grades 0.8 acres for a building pad and 0.4 acres for parking and access is a 1.2-acre disturbance and requires permit coverage.
When Is the EPA Construction General Permit Required?
In states and territories where the EPA is the NPDES permitting authority, construction operators must obtain coverage under the EPA’s Construction General Permit (CGP).
The current version is the 2022 CGP, effective February 1, 2022, and the EPA has proposed an updated 2027 CGP with more stringent technology-based effluent limitations.
The 2022 CGP imposes the following core requirements on covered operators:
Stormwater Pollution Prevention Plan (SWPPP)
Every operator must prepare a site-specific SWPPP before submitting a Notice of Intent.
The SWPPP must identify all potential pollutant sources on-site, describe the best management practices (BMPs), include a site map showing drainage patterns and BMP locations, and designate a qualified stormwater manager responsible for implementation.
The SWPPP is a living document that must be updated continuously to reflect current site conditions.
Notice of Intent (NOI)
Before disturbing any land, the operator must submit an NOI through the EPA’s NPDES eReporting Tool (NeT) system.
The NOI formally notifies the EPA that the project is covered under the CGP. Coverage becomes effective seven days after the NOI is submitted unless the project is in a sensitive water or impaired watershed that requires a 14-day review period.
Inspection Requirements
The CGP requires routine inspections by qualified personnel at minimum every seven calendar days and within 24 hours after any precipitation event of 0.25 inches or greater.
Inspections must be documented in writing, and records must be kept on-site and retained for at least three years after permit termination.
Effluent Limitations
The CGP prohibits discharges that cause or contribute to violations of state water quality standards, and it imposes specific discharge prohibitions including:
- Wastewater from concrete washout areas
- Turbid or sediment-laden discharges that visibly change the color or clarity of receiving waters
- Discharges containing floating solids, foam, or visible sheens
- Any discharge that causes or threatens to cause a fish kill
Corrective Action
When an operator identifies a BMP deficiency, the CGP requires the operator to initiate corrective action within 24 hours and complete it before the next rainfall event or by the next scheduled inspection, whichever comes first.
The corrective action and its outcome must be documented in the SWPPP.
Notice of Termination (NOT)
When construction is complete, and the site has achieved final stabilization—defined as uniform vegetative cover of at least 70 percent of the pre-disturbed density across all disturbed areas—the operator submits a Notice of Termination to close permit coverage.
Permit termination does not end the recordkeeping obligation; the operator must retain inspection reports and SWPPP documentation for three years after termination.
How State-Authorized Programs Work
The Clean Water Act allows states to apply for authorization to administer their own NPDES programs in place of the federal program.
Once a state receives EPA authorization, it issues its own construction stormwater permits, typically modeled on the federal CGP but often with additional or more stringent requirements.
The table below identifies the permit authority and primary construction stormwater permit for all 50 states, the District of Columbia, and major U.S. territories.
States with no authorized NPDES program operate under the EPA’s federal Construction General Permit.
| State | Permit Authority | Permit / Program | Trigger | Key Notes |
|---|---|---|---|---|
| Massachusetts | EPA (federal CGP) | EPA 2022 CGP | 1 acre | State Chapter 310 CMR 10 (wetlands) applies separately |
| New Hampshire | EPA (federal CGP) | EPA 2022 CGP | 1 acre | NH DES reviews separately under state law |
| New Mexico | EPA (federal CGP) | EPA 2022 CGP | 1 acre | State Construction Permit (CCPP) issued by NMED in coordination |
| Puerto Rico | EPA (federal CGP) | EPA 2022 CGP | 1 acre | EPA Region 2 administers directly |
| Guam | EPA (federal CGP) | EPA 2022 CGP | 1 acre | EPA Region 9 administers directly |
| District of Columbia | EPA (federal CGP) | EPA 2022 CGP | 1 acre | EPA Region 3 administers directly |
| Alabama | State (ADEM) | NPDES General Permit ALR100000 | 1 acre | Alabama Dept. of Environmental Management |
| Alaska | State (DEC) | AKR10B000 | 1 acre | Alaska Dept. of Environmental Conservation |
| Arizona | State (ADEQ) | AZG2022-001 | 1 acre | Arizona Dept. of Environmental Quality; full authorization |
| Arkansas | State (ADEQ) | ARR150000 | 1 acre | Arkansas Dept. of Energy & Environment |
| California | State (SWRCB) | Construction General Permit (CGP) 2022-0057-DWQ | 1 acre | Risk-tiered permit; requires SMARTS online filing; among most rigorous in the US |
| Colorado | State (CDPHE) | COR400000 | 1 acre | Colorado Dept. of Public Health & Environment |
| Connecticut | State (DEEP) | CPCS General Permit | 1 acre | CT Dept. of Energy & Environmental Protection |
| Delaware | State (DNREC) | DEG110000 | 1 acre | DE Dept. of Natural Resources & Environmental Control |
| Florida | State (FDEP) | FLR10E000 | 1 acre | Florida Dept. of Environmental Protection |
| Georgia | State (EPD) | GAR100001 | 1 acre | Georgia Environ. Protection Division |
| Hawaii | State (DOH) | HIG870000 | 1 acre | Hawaii Dept. of Health |
| Idaho | State (DEQ) | IDG100000 | 1 acre | Idaho Dept. of Environmental Quality; full authorization |
| Illinois | State (IEPA) | ILR10 | 0.1 acre (NPDES applies at 1 acre) | IL EPA requires permit at 5,000 sq ft on slopes >5% |
| Indiana | State (IDEM) | INR100000 | 1 acre | Indiana Dept. of Environmental Management |
| Iowa | State (DNR) | IOR10 | 1 acre | Iowa Dept. of Natural Resources |
| Kansas | State (KDHE) | KSR10 | 1 acre | Kansas Dept. of Health & Environment |
| Kentucky | State (DEP) | KYR10 | 1 acre | Kentucky Energy & Environment Cabinet |
| Louisiana | State (LDEQ) | LAR100000 | 1 acre | Louisiana Dept. of Environmental Quality |
| Maine | State (DEP) | MER10 | 1 acre | Maine Dept. of Environmental Protection |
| Maryland | State (MDE) | MDR100000 | 1 acre | MD Dept. of the Environment |
| Michigan | State (EGLE) | MIG610000 | 1 acre | MI Dept. of Environment, Great Lakes & Energy; full auth |
| Minnesota | State (PCA) | MNR100001 | 1 acre | MN Pollution Control Agency |
| Mississippi | State (MDEQ) | MSR100000 | 1 acre | MS Dept. of Environmental Quality |
| Missouri | State (MoDNR) | MOR100000 | 1 acre | Missouri Dept. of Natural Resources |
| Montana | State (DEQ) | MTR100000 | 1 acre | Montana Dept. of Environmental Quality |
| Nebraska | State (NDEE) | NER100000 | 1 acre | Nebraska Dept. of Environment & Energy |
| Nevada | State (NDEP) | NVR100000 | 1 acre | Nevada Div. of Environmental Protection |
| New Jersey | State (NJDEP) | NJG0105001 | 1 acre | NJ Dept. of Environmental Protection; strict soil erosion standards |
| New York | State (DEC) | NYR10A000 | 1 acre | NY Dept. of Environmental Conservation; ESCP required |
| North Carolina | State (DEQ) | NCG010000 | 1 acre | NC Dept. of Environmental Quality |
| North Dakota | State (NDDoH) | NDR10 | 1 acre | ND Dept. of Environmental Quality |
| Ohio | State (EPA) | OHC000004 | 1 acre | Ohio EPA; full authorization |
| Oklahoma | State (DEQ) | OKR10 | 1 acre | Oklahoma Dept. of Environmental Quality; full auth (ex. oil/gas) |
| Oregon | State (DEQ) | 1200-C | 1 acre | Oregon Dept. of Environmental Quality |
| Pennsylvania | State (DEP) | PAG-02 | 1 acre | PA Dept. of Environmental Protection; E&S Plan required; county conservation districts enforce |
| Rhode Island | State (DEM) | RIR10 | 1 acre | RI Dept. of Environmental Management |
| South Carolina | State (DHEC) | SCR100000 | 1 acre | SC Dept. of Health & Environmental Control |
| South Dakota | State (DENR) | SDR10 | 1 acre | SD Dept. of Agriculture & Natural Resources; full authorization |
| Tennessee | State (TDEC) | TNR100000 | 1 acre | Tennessee Dept. of Environment & Conservation |
| Texas | State (TCEQ) | TXR150000 (TPDES) | 1 acre | TX Commission on Environmental Quality; full authorization; TPDES Construction General Permit |
| Utah | State (DEQ) | UTR100000 | 1 acre | Utah Dept. of Environmental Quality; full authorization |
| Vermont | State (DEC) | 3-9020 | 1 acre | Vermont Dept. of Environmental Conservation |
| Virginia | State (DEQ) | VAR10 | 1 acre | VA Dept. of Environmental Quality; VSMP permit required |
| Washington | State (Ecology) | WAR100000 (CSWGP) | 1 acre | WA Dept. of Ecology; requires SWPPP + TESC Plan |
| West Virginia | State (DEP) | WV0115924 | 1 acre | WV Dept. of Environmental Protection |
| Wisconsin | State (DNR) | WIR10 | 1 acre | Wisconsin Dept. of Natural Resources; full authorization |
| Wyoming | State (DEQ) | WYR100000 | 1 acre | Wyoming Dept. of Environmental Quality |
Note: Permit numbers and agency names are current as of 2025. State programs update their general permits on varying cycles; typically every five years.
Always verify current permit requirements with the applicable state environmental agency before beginning earth disturbance.
Regulations Specific to Sensitive Watersheds and High-Risk Sites
Both the federal CGP and most state programs impose additional requirements on construction sites located near sensitive receiving waters or within impaired watersheds.
These enhanced requirements reflect the heightened risk that construction-site runoff poses to waters that already fail to meet water quality standards.
- Section 303(d) Impaired Waters: Requires states to identify polluted waters and establish Total Maximum Daily Loads (TMDLs); sites discharging into them face longer Notice of Intent (NOI) reviews, mandatory discharge assessments under the 2022 CGP, and stricter Best Management Practices (BMPs).
- Endangered Species Act (ESA) Compliance: Mandates operators evaluate potential impacts on listed species or critical habitats and implement required EPA consultation measures under both federal and state programs.
- Municipal Separate Storm Sewer Systems (MS4s): Projects within an MS4 service area must comply with local ordinances, creating a dual compliance requirement alongside state/federal permits that often requires local SWPPP review and stricter controls.
Navigating overlapping stormwater regulations on the federal, state, and local level requires careful planning to ensure site operations remain fully compliant across all sectors.
FAQs
Do I need a separate stormwater permit in every state where I work?
Yes. Each state with an authorized NPDES program issues its own construction stormwater permit, and coverage obtained in one state does not satisfy requirements in another. Operators working across state lines must hold permits in each state where they disturb land. In states where EPA directly administers the program, coverage is through the federal CGP, but operators must still submit a separate NOI for each project.
What is the difference between the federal CGP and a state construction permit?
The federal Construction General Permit is issued by the EPA and applies in states without an authorized NPDES program. Authorized state environmental agencies issue state construction stormwater permits under state law, but they must meet or exceed the federal CGP’s requirements. In practice, state permits often impose additional requirements that go beyond the federal baseline.
Are there stormwater regulations for projects under one acre?
Yes, in some states. The federal one-acre threshold is a minimum; states can and do require permits at lower thresholds. Illinois requires NPDES permit coverage for sites disturbing as little as 5,000 square feet on slopes greater than five percent. Additionally, the common plan of development rule means that a project disturbing less than one acre is still covered if it is part of a larger phased development that will ultimately disturb an acre or more.
What happens if construction starts before a permit is obtained?
Starting earth-disturbing activities before obtaining permit coverage violates the Clean Water Act. There is no grace period. The violation begins on the first day of earth disturbance and continues each day until you obtain permit coverage. Each day of unpermitted operation is a separate violation, each subject to per-day penalty calculations. Regulators can also require restoration of disturbed areas and installation of retroactive stormwater controls.