Last Updated 07/23/2026
Connecticut stormwater laws & regulations
The State of Connecticut operates under the National Pollutant Discharge Elimination System (NPDES) program under the authorization of the U.S. Environmental Protection Agency (EPA) through state regulation Regulations of Connecticut State Agencies R.C.S.A. §§ 22a-430-1— 22a-430-8. The Department of Energy and Environmental Protection (DEEP) manages the permitting and compliance of stormwater discharge.
Stormwater Associated with Commercial Activities (DEEP-WPED-GP-004): This general permit applies to all discharges from any conveyance which is used for collecting and conveying stormwater and which is directly related to retail, commercial, and/or office services whose facilities occupy five acres or more of contiguous impervious surface. Registration is required to be submitted in order for the discharges to be authorized by this general permit. Registrations are non-transferrable.
EXCERPT-General Permit for the Discharge of Stormwater Associated with Commercial Activity
PART II. DEFINITIONS
“Commercial activity” means any activity or facility under Standard Industrial Classifications (SIC) (as defined in “Standard Industrial Classification Manual, Executive Office of the President, Office of Management and Budget 1987”) 50-59 and 70-79, with five (5) acres or more of contiguous impervious surface. Impervious surface means roof area, paved walk, paved parking area, paved driveway, paved roadway and any other paved surface. An activity or facility with an SIC code already covered by the General Permit for the Discharge of Stormwater Associated with Industrial Activity is not included in this definition. See Appendix A for SIC code descriptions.
PART V. PERMIT CONDITIONS
B. STORMWATER MANAGEMENT PLAN
The permittee shall prepare, implement and maintain a Stormwater Management Plan (the “Plan”) which shall consist of all records, schedules, narrative, instructions or other materials kept on file at the registrant’s facility in accordance with the Stormwater Management Measures and other provisions of Part V of this general permit.
2. Stormwater Management Measures
The Stormwater Management Plan shall be maintained on a form prescribed and provided by the Commissioner and shall, at a minimum, contain the following:
a. Pollution Prevention Team
The permittee shall designate a Pollution Prevention Team consisting of personnel, at least one of who must be working at the site, to carry out the provisions of these Stormwater Management Measures.
b. Sweeping
All parking areas, sidewalks, driveways and other impervious surfaces (except roofs) shall be swept clean of sand, litter and any other possible pollutants at least twice a year, once between November 15 and December 15 (after leaf fall) and once during the month of April (after snow melt) and at other times as may be necessary.
c. Outside Storage
Any raw materials, intermediate products, by-products, final products, waste materials, accessories or equipment stored outside shall be covered or moved inside, if possible, or maintained in such as manner as to avoid, if at all possible, the risk of any of these materials or their residue passing to a stormwater discharge.
d. Washing
No water resulting from washing of any raw materials, intermediate products, by-products, final products, waste materials, accessories, equipment, storage areas, outside sales/garden areas, loading docks, parking areas or vehicles shall be discharged to a stormwater collection system or waters of the state (including, but not limited to, surface waters or wetlands) except in accordance with a permit issued by the DEEP pursuant to Section 22a-430 or 22a-430b of the Connecticut General Statutes.
e. Spill Control
The permittee shall prepare and implement a Spill Control and Response Plan (“Spill Plan”) for any raw materials, intermediate products, by-products, final products, waste materials, accessories or equipment present at the facility which could possibly discharge to the stormwater collection system or waters of the state. The Spill Plan shall include measures to avoid spills in areas exposed to rainfall or from reaching areas exposed to rainfall. The Spill Plan shall also include response measures to best prevent a spill from being exposed to stormwater or entering a stormwater collection system or waters of the state once it has occurred.
The Spill Plan shall identify areas where potential spills can occur and the location of associated collection and discharge points. The Spill Plan shall include procedures for cleaning up spills including, without limitation, procedures for insuring that appropriate personnel are trained or otherwise notified of measures to take in the event of a spill. The necessary equipment to implement a cleanup shall be listed in the Spill Plan and locations designated such that this equipment shall be available to personnel in all areas where spills may occur. The Spill Plan shall provide that all areas in which a spill could potentially discharge to stormwater and where liquid chemicals are stored are provided with impermeable containment which will hold at least the volume of the largest chemical container, or 10% of the total volume of all containers in the area, whichever is larger, without overflow from the containment area. For commercial activities initiated after the date of this general permit, the Spill Plan shall provide that all chemicals in containers of 100 gallons or less shall be stored under a roof that minimizes stormwater entry to the containment area.
The Spill Plan shall also provide that all dumpsters used to store waste or recyclable materials are supplied with attached covers and have drain plugs intact, or are in roofed areas that will keep rain out of the dumpster and will not allow dumpster leakage to enter any stormwater drainage system.
f. Maintenance and Inspection
The permittee shall prepare and implement a facility maintenance plan. The facility maintenance plan shall include good housekeeping measures to ensure that all areas exposed to stormwater are kept in such a condition as to minimize the possibility of discharging pollutants into a stormwater collection system or waters of the state. The plan shall include provisions for a monthly inspection by a member of the Pollution Prevention Team of all areas covered by the plan, a weekly inspection of the site for surface debris and the monthly inspection of all stormwater structures and outfalls on the site for floating or surface debris and sediment. Structures and outfalls shall be cleaned of sediment and debris at least once a year during the month of April and at other times as necessary to prevent the discharge of pollutants from structures or outfalls.
g. Employee Training
The permittee shall ensure that all employees whose activities may affect stormwater quality receive training upon employment and at least once a year thereafter to make them familiar with these stormwater management measures. Training shall be conducted by a member of the Pollution Prevention Team.
h. Comprehensive Annual Stormwater Evaluation and Inspection
Once a year, a member of the Pollution Prevention Team shall conduct a Comprehensive Annual Stormwater Evaluation and Inspection. All aspects of the stormwater collection and/or treatment system shall be inspected for consistency with the Stormwater Management Plan. A report of the results of this inspection shall be prepared and a copy maintained on site. This report shall also be reviewed and signed by the permittee as specified in Part IV.C.2.c. above. Based on this report, the permittee shall revise the Plan as necessary to maintain consistency with this general permit.
i. Record Keeping
The permittee shall ensure that oil and sediment control structures or devices are used within the drainage system for all construction which i) may impact the drainage system and ii) occurs on site on or after the effective date of this general permit. Note that any construction activity that disturbs greater than 5 acres must be registered and conducted in accordance with the General Permit for the Discharge of Stormwater and Dewatering Wastewaters from Construction Activities, as amended. In addition, the permittee shall avoid, wherever possible, the use of copper or galvanized roofing or building materials for any new construction where these materials will be exposed to stormwater.
3. Keeping Plan Current The permittee shall update the Plan annually and shall amend the Plan whenever; (1) there is a change at the site which may affect the potential of stormwater discharges from the site to cause pollution of the waters of the state; (2) there is a change in the Pollution Prevention Team; (3) the actions required by the Stormwater Management Measures fail to ensure or adequately protect against pollution of the waters of the state; or (4) the Commissioner requests modification of the Plan. The permittee shall amend the Plan as necessary to address any sources or potential sources of pollution identified as a result of a Comprehensive Annual Stormwater Evaluation and Inspection conducted pursuant to Part V.B.2.h. of this general permit. The amended Plan and all actions required by the Plan shall be completed within 60 days of the date the permittee becomes aware or should have become aware that any condition identified in this paragraph has occurred.
C. REPORTING REQUIREMENTS
1. The permittee shall keep a copy of the Stormwater Management Plan onsite at all times. The permittee shall make a copy of the Plan available to the Commissioner immediately upon request, and, in the case of a stormwater discharge associated with commercial activity that discharges through a municipal separate storm sewer system, to the operator of the municipal system upon request. In the case of a stormwater discharge associated with commercial activity that discharges to a water supply watershed, copies of the Plan shall be made available upon request to the public water supply company.
2. The Commissioner may notify the permittee at any time that the Plan does not meet one or more of the requirements of this Part. Unless otherwise notified by the Commissioner in writing, within 30 days of the date of such notification from the Commissioner, the permittee shall revise the Plan, perform all actions required by the revised Plan, and shall submit to the Commissioner, in writing, certification that the requested changes have been made and implemented and such other information as the Commissioner may require.
Purpose: These guidelines have been developed to clarify DEEP recommendations to state and municipal officials, and others regarding the removal and disposal of snow accumulations from roadways and parking lots. For purposes of this guidance snow accumulations refers to snow banks and snow piles that are removed by front-end loader or by loading on trucks for disposal. This guidance does not apply to normal snow plowing operations that must, inevitably, discharge some snow into wetlands and watercourses.
Implementation: While following these guidelines does not constitute a permit or authorization, the Department recognizes there is a considerable need for flexibility in implementation of this policy, particularly in emergency situations. There is no intent to interfere with snow plowing operations. Where trucking and snow dumping operations are undertaken the Department recommends these guidelines be followed.
Recommended Management Practice: Snow accumulations removed from roadways, bridges, and parking lots should be placed in upland areas only, where sand and other debris will remain after snowmelt for later removal. Care must be exercised not to deposit snow in the following areas:
- freshwater or tidal wetlands or in areas immediately adjacent to such areas where sand and debris may be flushed during rainstorms;
- on top of storm drain catch basins;
- in storm drainage swales;
- on stream or river banks which slope toward the water, where sand and debris can get into the watercourse; and
- in areas immediately adjacent (within at least 100 feet) of private or public drinking water well supplies (due to the possible presence of road salt).
Notification: Notification can be made by addressing an email to Dahlia Gordon at: [email protected]. The notification must include the following: (1) the name of the governmental entity making the notification; (2) contact information for the governmental entity including name, email address and phone number; (3) the street address where the snow disposal activity will occur; (4) the name of the waterbody where the snow will be disposed; (5) the estimated quantity of snow to be disposed; (6) the dates during which the disposal activity will occur; and (7) a statement that the governmental entity has exhausted all disposal alternatives and snow management methods and will make best efforts to adhere to these snow disposal guidelines.
Information: For further information please call the Water Permitting and Enforcement Division Engineer of the Day at 860-424-3025.
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Frequently Asked Questions
Does my commercial property need a stormwater permit in Connecticut?
It depends on your impervious surface. The Commercial Activity general permit applies to retail, commercial, and office facilities with five acres or more of contiguous impervious surface, covering roofs, paved walks, parking areas, driveways, and roadways. If your facility falls under that threshold, registration with DEEP is required before your discharges are authorized, and registrations can’t be transferred to a new owner.
Do I need to designate specific staff for stormwater compliance in Connecticut?
Yes. Registered facilities have to designate a Pollution Prevention Team, with at least one member actually working on-site, responsible for carrying out the Stormwater Management Plan’s requirements.
How often do I need to sweep parking lots and pavement under Connecticut's commercial permit?
At least twice a year, once between November 15 and December 15 after leaf fall, and once in April after snowmelt, plus additional sweeping whenever necessary. That schedule applies to all impervious surfaces except roofs.
Does Connecticut require a spill response plan for my commercial property?
Yes. The Spill Control and Response Plan has to identify where spills could occur, list cleanup equipment and its location, and ensure liquid chemical storage areas have containment sized to hold the largest container or 10% of total stored volume, whichever is larger. Chemical containers of 100 gallons or less at facilities built after the permit’s effective date also have to be stored under a roof.
How often do I need to inspect my stormwater structures under Connecticut's commercial permit?
On a layered schedule: weekly for surface debris across the site, monthly for all covered areas and for stormwater structures and outfalls, and once a year for a full Comprehensive Annual Stormwater Evaluation and Inspection. Structures and outfalls also have to be cleaned of sediment and debris at least once a year in April, and as needed beyond that.
Do employees need stormwater training at a Connecticut commercial facility?
Yes, upon hire and then annually. Training has to be conducted by a member of the Pollution Prevention Team and cover the facility’s stormwater management measures directly.
What records does DEEP expect me to keep on-site under the Commercial Activity permit?
A fairly complete file: weekly and monthly inspection records, the Spill Plan, sweeping schedule, structure cleaning schedule, employee training schedule, annual evaluation reports, and a current list of Pollution Prevention Team members. All of it has to be available for DEEP’s immediate inspection on request.
When do I need to update my Stormwater Management Plan in Connecticut?
Every year at minimum, and immediately whenever a site change could affect pollution potential, the Pollution Prevention Team changes, existing measures fail to protect water quality, or DEEP requests a modification. Once a triggering condition is identified, the amended plan and any resulting actions have to be completed within 60 days.
Are there restrictions on where snow can be dumped from my Connecticut property?
DEEP recommends against it in several sensitive locations: wetlands or areas near them, on top of catch basins, in drainage swales, on stream banks that slope toward water, and within 100 feet of drinking water wells. These are guidelines rather than a permit requirement, but they reflect the same pollution-prevention logic that runs through the rest of the commercial permit.
Are there restrictions on where snow can be dumped from my Connecticut property?
AQUALIS helps Connecticut property owners with five acres or more of impervious surface prepare and maintain the required Stormwater Management Plan, implement the sweeping, spill control, and inspection schedules DEEP requires, and complete the annual Comprehensive Stormwater Evaluation before a plan falls out of date.
The information on this page is provided for general informational purposes only and is not legal advice. Regulations change frequently — AQUALIS makes no warranty as to the accuracy or completeness of this content, and any reliance on it is at your own risk. Consult a qualified professional or your local regulatory authority to confirm requirements applicable to your specific property.
