U.S. Stormwater Regulation Directory

Agency: ADEM

Threshold: ≥ 1 acre of land disturbance, or < 1 acre if part of a larger common plan of development or sale

Agency: DEC

Threshold: ≥ 1 acre of land disturbance, or < 1 acre if part of a larger common plan of development or sale

Agency: ADEQ

Threshold: ≥ 1 acre of land disturbance, or < 1 acre if part of a larger common plan of development or sale

Agency: DEQ

Threshold: ≥ 1 acre of land disturbance, or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre

Agency: SWRCB

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan)

Agency: CDPHE WQCD

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development exceeding 1 acre)

Agency: DEEP

Threshold: ≥ 1 acre of land disturbance, or < 1 acre if part of a larger common plan of development or sale; also applies to any dewatering discharges from construction sites of any size

Agency: DNREC

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale)

Agency: FDEP

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan)

Agency: EPD

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale); ≥ 5 acres triggers additional land disturbance activity permit requirements under state law

Agency: DOH-CWB

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale); some activities < 1 acre may require an individual NPDES permit depending on proximity to sensitive waters

Agency: IDEQ

Threshold: Section 1.1 covers an operator of construction that will disturb one or more acres of land, or less than one acre that is part of a common plan of development or sale that will ultimately disturb one or more acres, and construction DEQ designates as needing coverage under 40 CFR 122.26(a)(1)(v) or 40 CFR 122.26(b)(15)(ii). The activities must be in Idaho where DEQ is the permitting authority, and not within tribal reservation boundaries (Section 1.1.3).

Agency: IEPA

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale); Chicago Metropolitan Agency for Planning (CMAP) area may have additional requirements through local MS4 permits

Agency: IDEM

Threshold: ≥ 1 acre of land disturbance; < 1 acre if part of a larger common plan of development or sale

Agency: IDNR

Threshold: ≥ 1 acre of land disturbance; < 1 acre if part of a larger common plan of development or sale

Agency: KDHE

Threshold: ≥ 1 acre of land disturbance; < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre

Agency: DOW

Threshold: ≥ 1 acre of land disturbance; < 1 acre if part of a larger common plan of development or sale expected to disturb ≥ 1 acre in total

Agency: LDEQ

Threshold: ≥ 5 acres of land disturbance, including disturbance of less than 5 acres that is part of a larger common plan that will ultimately disturb ≥ 5 acres

Agency: DEP

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale)

Agency: MDE

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale); sites disturbing < 5,000 sq ft in certain Priority Protection Areas may also require coverage

Agency: MassDEP

Threshold: Disturb 1 acre or more, or disturb less than 1 acre as part of a common plan of development or sale that will ultimately disturb 1 acre or more (2022 CGP Part 1.1.2). EPA is the permitting authority for those discharges (Appendix B).

Agency: EGLE

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale); Michigan also requires permit coverage for any activity that discharges to a water of the state with potential to cause or contribute to a water quality violation

Agency: MPCA

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale); Minnesota's permit also applies to all construction activity that discharges to a Special Water or impaired water regardless of acreage

Agency: MDEQ

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre)

Agency: MDNR

Threshold: ≥ 1 acre of total land disturbance (or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre); also applies to any earth-disturbing activity that the Director determines has the potential to cause water quality violations

Agency: MT DEQ

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre); individual construction sites < 1 acre may also require coverage if they discharge to impaired waters

Agency: NDEE

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre)

Agency: NDEP

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre). Note: Nevada is a predominantly arid state, and many small sites that would not generate discharge in wetter climates are still required to obtain coverage.

Agency: NHDES

Threshold: Disturb 1 acre or more, or disturb less than 1 acre as part of a common plan of development or sale that will ultimately disturb 1 acre or more (2022 CGP Part 1.1.2). Part 9.1.1 also requires an NHDES Alteration of Terrain permit, unless exempt, if you disturb 100,000 square feet or more of contiguous area, or 50,000 square feet or more when construction occurs within the protected shoreline under the Shoreland Water Quality Protection Act. A project must also file if it disturbs an area greater than 2,500 square feet, is within 50 feet of any surface water, and has a flow path of 50 feet or longer disturbing a grade of 25 percent or greater. Smaller sites that could affect state surface waters are subject to the Alteration of Terrain General Permit by Rule (Env-Wq 1503.03). The current rule uses a different area test. Env-Wq 1502.60, effective August 6, 2026 (Register document #14656), defines significantly altering the terrain, and example (b) is earth moving that, over a 10-year period, cumulatively exceeds 100,000 square feet, or 50,000 square feet if any portion of the disturbance is within the protected shoreland as defined in RSA 483-B:4, XV, calculated under Env-Wq 1503.12. Both the permit's contiguous test and that 10-year cumulative example are published here. Rule text: https://gc.nh.gov/rules/state_agencies/env-wq1500.html

Agency: NJDEP

Threshold: ≥ 1 acre of total land disturbance, or < 1 acre if part of a larger common plan of development or sale that will disturb ≥ 1 acre in total. Individual lot disturbances < 1 acre in a larger subdivision require coverage.

Agency: NMED

Threshold: Disturb 1 acre or more, or disturb less than 1 acre as part of a common plan of development or sale that will ultimately disturb 1 acre or more (2022 CGP Part 1.1.2). Appendix B lists NMR100000 for the State of New Mexico except Indian country, and NMR10I000 for Indian country within New Mexico except Navajo Reservation lands covered under Arizona permit AZR10I000 and Ute Mountain Reservation lands covered under Colorado permit COR10I000. The Region 6 row of Appendix B prints those cross-references as AZR10000I and COR10000I. Coverage under NMR10I000 follows Part 9.6.2. The permit states a geographic limit for two of those pueblos. Pueblo of Sandia: "The following conditions apply only to discharges on the Pueblo of Sandia Reservation." Pueblo of Santa Ana: "The following conditions apply only to discharges on the Pueblo of Santa Ana Reservation." For the Pueblo of Isleta, Part 9.6.2 uses "exterior boundaries of the Pueblo of Isleta" in the NOI-copy sentence, "for projects occurring within the exterior boundaries of the Pueblo of Isleta," and in the sediment-disposal sentence, "if sediment is placed for disposal within the exterior boundaries of the Pueblo of Isleta, disposal must be within a tribally approved sediment disposal site." Nambe Pueblo, Ohkay Owingeh, Pueblo of Laguna, Pueblo of Taos, Pueblo of Tesuque, and Santa Clara Indian Pueblo are named in Part 9.6.2, and their geographic scope is left unstated. Appendix B also lists 06R10F000 for all Lands of Exclusive Federal Jurisdiction in Region 6.

Agency: NYSDEC

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan). NYC East of Hudson watershed: ≥ 5,000 sq ft. City of New York municipal boundaries: ≥ 20,000 sq ft.

Agency: NCDEQ

Threshold: ≥ 1 acre of land disturbance, or < 1 acre if part of a larger common plan of development or sale that will disturb ≥ 1 acre. NC also regulates land-disturbing activity ≥ 500 sq ft under the NC Sedimentation Pollution Control Act (SPCA) of 1973, which is a parallel but distinct state requirement.

Agency: NDDEQ

Threshold: ≥ 1 acre of total land disturbance, or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre. Linear projects (pipelines, roads) use total disturbance area for threshold calculation.

Agency: Ohio EPA

Threshold: ≥ 1 acre of land disturbance, or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre

Agency: ODEQ

Threshold: ≥ 1 acre of land disturbance, or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre

Agency: Oregon DEQ

Threshold: ≥ 1 acre of land disturbance, or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre; projects < 1 acre not part of a common plan are generally exempt from 1200-C

Agency: PA DEP

Threshold: ≥ 1 acre of earth disturbance, or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre; Pennsylvania also requires a separate E&S permit (via Chapter 102) for all earth disturbance ≥ 5,000 sq ft (approximately 0.11 acre)

Agency: RIDEM

Threshold: ≥ 1 acre of land disturbance, or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre

Agency: SCDES

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre)

Agency: DANR

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre); sites disturbing ≥ 5 acres that discharge to waters of the state require a Notice of Intent

Agency: TDEC

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre); all sites must also comply with Tennessee's Construction General Permit and the Stormwater Management Act

Agency: TCEQ

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development)

Agency: UDEQ

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre); Utah administers this under its own UPDES (Utah Pollutant Discharge Elimination System) program, which is the state equivalent of NPDES; the current CGP permit number is UTRC00000 (effective July 1, 2024)

Agency: DEC

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre); Vermont also regulates stormwater from smaller sites through its municipal stormwater program and Act 250 land use review process; sites disturbing ≥ 1 acre in regulated watersheds may face additional requirements under the Vermont Stormwater Management Rule

Agency: VDEQ

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre)

Agency: Ecology

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan)

Agency: WVDEP

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre)

Agency: WDNR

Threshold: ≥ 1 acre of land disturbance; also applies to sites < 1 acre that are part of a larger common plan of development or sale disturbing ≥ 1 acre; Wisconsin additionally requires a Notice of Intent for sites disturbing ≥ 4,000 sq ft in certain MS4 areas under local ordinance (not state permit threshold)

Agency: WDEQ

Threshold: ≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acre)