Connecticut Department of Energy & Environmental Protection

Compensatory Water Resource Mitigation

What is Compensatory Mitigation?

restoration work consisting of new plantings and plugs, stone rip rap, and waddles installed

Compensatory Mitigation is taking action to restore, create, and/or enhance wetlands and/or other water resources – with a goal of gaining resource area and/or improving resource functions – to compensate for impacts. Mitigation should only occur after resource avoidance and minimization have been achieved to the greatest extent practicable. Compensation for impact is warranted by the Federal Clean Water Act in 33 CFR Part 332, Compensatory Mitigation for Losses of Aquatic Resources, and may be warranted by state or municipal authorities that authorize impacts.

Mitigation Guidance Coming Soon!

Mitigation guidance materials will increase the transparency, consistency, and predictability of mitigation projects. DEEP’s LWRD Division is developing a comprehensive statewide mitigation program to address compensation for impacts to water resources. Program guidance materials are coming soon, to help stakeholders navigate the mitigation process. 

What water resource impacts might warrant compensatory mitigation?

DEEP’s Water Resource Mitigation program applies if unavoidable impacts occur to Connecticut’s water resources, including tidal wetlands and other tidal/coastal/navigable waters, intertidal flats, and inland wetlands and watercourses. Impacts to any wetlands, streams, lakes, ponds, pools, or other water types, natural or artificial, may warrant compensation to offset the impact.

  • In tidal and coastal areas, DEEP has authority over tidal wetlands and other tidal, coastal, and navigable waters, including tidally influenced waters.
  • In inland areas, Connecticut has 191 municipal Inland Wetland Commissions which each hold broad authority over inland water resources inside their respective political boundaries. The exception is that DEEP has authority over State activities, activities on State land, and in State 401 Water Quality Certifications for inland projects that warrant Federal 404 permits.

How does water resource mitigation get done?

There are 3 main pathways to provide compensation by performing compensatory mitigation: restoration, creation, or enhancement of water resources.
  • Restoration: Re-establishment of a former wetland or water resource to natural/historic conditions by manipulating the physical, chemical and/or biological characteristics of an area. Restoration results in a gain of water resource area and its associated functions/values.
  • Creation: Establishment of a new wetland or other water resource that did not previously exist by manipulating the physical, chemical, and/or biological characteristics of an area. Creation results in a gain of new water resource area and its associated functions/values.
  • Enhancement: Improvement of an existing water resource by adding or heightening its functions through manipulation of the physical, chemical, and/or biological characteristics of a resource. Enhancement does not result in a gain of water resource area however it may add to and/or improve existing resource functions/values.

Is compensatory mitigation happening in Connecticut?

Yes, DEEP is requiring some project proponents to provide Permittee Responsible Mitigation, or PRM, to offset resource impacts if they are unavoidable and significant. PRM is compensation that must be provided by the permittee to offset resource impacts, and the mitigation (compensation) gets approved under the same permit as the impacts. With PRM projects, proponents submit a Mitigation Plan in the permit application for DEEP approval, and the permittee is responsible for the mitigation. DEEP is currently working to develop additional mitigation options other than PRM, such as mitigation banking and/or a state in-lieu fee program; these modern programs offer mutual benefits to permittees, staff, and the environment.

Image showing five major mutual benefits of implementing modern mitigation, including: streamlining permitting, reducing permittee burden, growing Connecticut’s environmental economy, and increasing expert management of projects and overall project success.

*Mitigation Consultations are Available* 

To request a mitigation consultation, please email WaterResourceMitigation@ct.gov. DEEP encourages project proponents to consult with staff prior to submitting an LWRD license application to ensure that, if warranted, mitigation is provided in the license application to address proposed impacts. If compensation is needed, a Mitigation Plan [or acceptable equivalent] may need to be submitted for DEEP review and approval.

Mitigation pre-application consultation is recommended if your project proposes permanent impacts to tidal wetlands or intertidal flats, or significant impacts to streams or inland waters [if the project is state activity, state land, or warrants state 401 Water Quality Certification].

In addition to DEEP, municipal inland wetland commissions and the federal USACE may also warrant compensation for loss in Connecticut, under their respective laws, programs and policies.

Mitigation Resources

State Guidance: 

  • Pre-Application Consultation Form (coming soon)

Federal Guidance:

Who can I contact with questions about compensatory mitigation?

For mitigation-related questions please email WaterResourceMitigation@ct.gov. 

Stay tuned - more mitigation content is coming soon!

marsh with grasses and water.

Degraded Brides Brook Salt Marsh, Rocky Neck State Park, East Lyme, CT

side by side photos of field of dried grasses and restored marsh with green grasses and water.

Mitigation Before/After Photos: Restoring Agricultural Ditch to Wetland

Dry marsh with newly planted grass plugs and mature grass and river in distance.

Great Meadows Tidal Marsh Restoration, Stratford, CT

Content last updated March 27, 2025