Water Source Protection Measures

A watershed can be defined as "an area of land that drains water, sediment, and dissolved materials to a common receiving body or outlet. The term is not restricted to surface water runoff and includes interactions with subsurface water.

Watershed Protection Measures

Figure 1: Watershed illustration - A watershed can be defined as "an area of land that drains water, sediment, and dissolved materials to a common receiving body or outlet. The term is not restricted to surface water runoff and includes interactions with subsurface water."The Groton Utilities water treatment plant takes reservoir (source) water and treats it to become public drinking water for supply to the local community and greater region. Watershed protection measures are the first steps, or barriers, as part of a multi-barrier approach to protecting and improving water quality at Groton Utilities.

A watershed is defined as a land area that channels rainfall and snowmelt to groundwater, creeks, and streams, and eventually to outflow points such as reservoirs, bays, and the ocean. Roughly 2,800 acres of watershed forest are owned and managed by Groton Utilities as the first line of defense of water quality protection.

Watershed forests on land surrounding the streams and reservoirs provide important water treatment services. Some of these services include bank and land stabilizations, allowing water a chance to percolate through leaf cover / ground and receiving natural filtration, providing shade (temperature buffering), settling out of particles, nutrients, and chemicals, reduction of erosion and sedimentation and reduction of stormwater run-off.

Wetlands are areas where the soil is saturated or covered by water at least seasonally. These sensitive areas help protect water quality through erosion control and water storage. They're also important for pollution control specifically through sediment trapping, nutrient removal, and chemical detoxification. Wetland plants contribute to water quality through nutrient reduction and erosion barriers.

The passage of water through reservoirs and the movement of water with change in velocity and temperature from one body to another promotes aeration, agitation, and mixing followed by settling out of larger particles in quiescent reservoirs. These water treatment services are provided naturally even before reaching the treatment plant and, if managed properly, provide water that requires less treatment and less expense.

These barriers to contaminants entering the water better position the water treatment plant to meet increasing Federal and Connecticut State regulations for water quality.

Figure 2: Conventional water treatment process diagram.

Groton Utilities Watershed & Reservoirs

Groton Utilities source water supply includes five surface water reservoirs that span from the Town of Ledyard in the north, south to the Town of Groton. The upper system includes Billings Avery Pond and diversion channel, Morgan Reservoir, and Ledyard Reservoir. The lower system, located in the Town of Groton, consists of Poheganut Reservoir, Smith Lake, and Poquonnock Reservoir, the terminal reservoir, and site of the water treatment plant. The total watershed drainage area for the supply is 15.6 square miles. Approximately 2,800 acres or 28% of the total watershed is owned by Groton Utilities. This land surrounds reservoirs and tributary streams and consists mainly of wetlands and forested land. Forested watershed land is important for water quality in the natural services previously mentioned. Conventional water treatment plant processes are modeled after the natural processes that occur in forest watersheds, streams, and reservoirs.

Land Protection

Groton Utilities has worked with local conservation and open space interest groups such as Groton Open Space Association and Avalonia Land Conservancy in support of their efforts of land and aquifer protection and open space with the aim of protecting water quality, preserving forest land, and allowing for open space activities.

In 2019 Groton Utilities worked in partnership with Avalonia Land Conservancy for their purchase and protection of two parcels, a combined total of 228 acres of watershed land and eight miles of trails in Ledyard.

In 2021, Groton Utilities worked cooperatively to identify and map existing regional trails, greenways, parks, conserved land, and open space with demonstrated present and future connectivity for the community. This project is a partnership with local environmental and conservation partners, including Avalonia, GOSA, and Tri-Town Trails, as well as the Departments of Planning, Parks and Recreation, and Public Libraries from the Towns of Ledyard and Groton.

In November 2021, Groton Utilities presented the cooperative project to the Southeastern Connecticut Council of Government for future leadership.

Land Ownership & Protection

Figure 3: Morgan Pond ReservoirIn recognizing the direct impact that land use has on water quality -ownership of watershed land and partnerships are the best way to ensure water quality protection. As certain opportunities arose, Groton Utilities has purchased critical parcels of land within the watershed for water quality protection. Receipt of Connecticut Department of Energy and Environmental Protection's Open Space and Watershed Lands Grants on two properties provided partial funding to acquire parcels within the watershed.

The remainder of Groton Utilities watershed, aside from the Utility owned property, is made up of a variety of other types of land use that contribute to source water. In areas that are more urbanized, the amount of impervious cover is greater than undeveloped areas marked by natural land cover. Impervious cover includes surfaces that water does not infiltrate through - roofs, roads, driveways, sidewalks, and parking lots. When rain falls on and travels over these surfaces it is likely to pick up other materials along the way and transport them to waterways (fertilizer and pesticides, bacteria, oil or fluids, dirt, sand, and salt, as well as other litter). Since these substances get washed into waterways by rain and snow melt it is important to monitor land use activities in the watershed and protect water at its source.

Sanitary Survey - Surveillance

Given that land use in the watershed directly impacts source water quality, water companies are required by the Connecticut Public Health Code to inspect all types of properties within their watershed annually to ensure pollution sources are minimized. This program of Sanitary Survey Inspections is another source protection measure. Trained Watershed Inspectors from Groton Utilities attempt to visit all properties in the watershed of Groton and Ledyard to look at conditions that have the potential to impact water quality. These conditions include septic systems, fuel, and chemical storage, lawns with respect to fertilizer and pesticide use and storage, waste, construction activities, etc. Watershed Inspectors offer relevant handouts as resources to watershed residents on local options for household hazardous waste and paint disposal and non-chemical alternatives for lawn and garden care.


Groton Utilities Watershed Surveillance and Patrol Department monitor reservoir and watershed property daily, read stream gauge stations, and collect water samples at streams and reservoirs to be processed at Groton Utilities Water Quality Laboratory. Throughout the year Staff maintain property boundary markings and signage, conduct Watershed Site Inspections, work with state agencies regarding migratory bird and wildlife populations, work with forestry operations, oversee ground maintenance, and respond to emergency events such as storms, fires, spills, etc. Supervised educational tours are given to schools and other groups upon request.

Currently, all tours are on hold due to the COVID-19 health situation as well as the construction of the new water treatment plant.

Check out a short video about the 2017 to 2020 Upgrade to Water Treatment Plant.

Also, see the most recent news article: Water Treatment Plant Upgrade More Than Half-Way Complete, published in the New London Day:

Security - Limited Access

Much of Groton Utilities watershed property is fenced with marked boundaries and is posted as this land is not open for hunting, trapping, or fishing. There is presently limited recreational access for the security and safety of source water. We participate with various educational faculties and environmental groups to allow scientific research in watersheds including algal studies, glaciation, forestry, plants, and wildlife. Figure 4: Hikes along the Ledyard watershedOccasional tours and access are provided by Groton Utilities. Written permission is required for access. Groton Utilities partners with Denison Pequotsepos Nature Center who lead escorted hikes in the Ledyard watershed throughout the year.

Additionally, Groton Utilities hosts, at a minimum, three educational tours of the upper watershed for residents of Ledyard each year. These hikes are coordinated on behalf of Ledyard Libraries through Groton Utilities and Ledyard Parks and Recreation.

Emergency Response

Groton Utilities maintains an emergency response trailer stocked with absorbent materials and spill containment equipment. A team of employees is trained to respond in case of emergency to assist first responders. Protocol and mutual aid agreements are in place with local fire and emergency services and a collaboration of Connecticut's Water / Wastewater Agency Response Network - CtWARN. Groton Utilities maintains an oil boom and turbidity curtains in key locations in reservoirs as part of water quality control for turbidity and spill protection.

Figure 5: Groton Utilities Emergency Response Unit. Photo from GU WS&P.

Scientific Management

Groton Utilities employs a limnologist consultant for source water quality and improvements.

Groton Utilities Drinking Water Quality Management Plan

With the development of two parcels in close proximity to the terminal reservoir system, Groton Utilities in 2000 initiated discussions with local community stakeholders to protect water quality and to educate businesses and the general public with respect to stormwater runoff impacts to drinking water supplies. These discussions included meetings with watershed towns and the Connecticut Department of Public Health, building an awareness that watersheds cross community lines, and that maintaining future water quality would require crucial input from all stakeholder communities in order to develop partnerships for resource protection - both for existing and for future water supply sources.

Subsequently, Groton Utilities -through a grant from the Connecticut Department of Public Health retained a consulting engineering firm to assist in the development of a Drinking Water Quality Management Plan. The Plan was finalized in 2008 and now provides a basis for watershed land protection and water quality protection for existing and future water resources while allowing for planned development in accordance with guidelines set forth therein.

Work with Watershed Towns

Groton Utilities works with the Towns of Ledyard and Groton on Planning and Zoning Department matters within the watershed. Groton Utilities Water Project Managers and consultants review site plans and provide comments on development in the watershed.

Figure 6: Ledyard Reservoir

Groton Utilities has a Memoranda of Understanding program specifically for stormwater and drainage runoff at new businesses and large-scale residential site developments in the Town of Groton. This is a written agreement made between Groton Utilities and a property owner that ensures long-term maintenance of stormwater quality structures and protections. On-going stormwater sampling and Best Management Practices are part of these agreements including the use of non-chemical lawn care, use of organic fertilizer, protective measures for trash collection, and winter de-icing operations with limited use of sodium. See an example of other watershed Best Management Practices for stormwater.

Management from Groton Utilities was invited to participate with the Town of Groton's Planning and Development team during their recent update of a zoning overlay known as a Water Resource Protection District. This District strengthens protections for roughly 7,700 acres in the Groton watershed including tributaries, streams, and reservoirs. Land use, including limits on material storage and waste disposal within the District, is regulated to protect current and future drinking water resources.

Map of the Town of Groton Water Resource Protection District (PDF)

Forest Health & Management

Forestry management is one of the first and best barriers to achieving high water quality.

A forest filters and purifies water. It is important to maintain a healthy, resilient, and disease-resistant forest for this purpose. The best way to do this is to have a diversity of tree species, ages, and sizes that is enhanced by forest management. Such diversity ensures that any large disturbance (disease outbreak, insect outbreak, storm event) will have much less of a negative impact. For example, by having many species besides oak or ash, the forest is resilient to the impending outbreak of emerald ash borer or of the gypsy moth infestation. By having many areas of young healthy trees, the forest is less vulnerable to a forest-wide loss of tree cover. Loss of tree cover results in increased exposure of the forest floor to sunlight and precipitation and an associated increase in nutrient and sediment runoff into the reservoirs. A forest mosaic, having a variety of tree ages and sizes, is more resilient to forest-wide disturbances while continuing to function as a filter for the reservoirs.

Figure 7: Three ways Healthy Forests Support Clean Water. World Resources Institute.

Over the last 50 years GU forestry operations have been directed by successive long-term Forest Management Plans, tree planting, firewood harvesting, field mowing, protection of wetlands, occasional timber harvests, and non-commercial timber stand improvements have been carried out.

The current Forest Management Plan (2019) was created with a certified Connecticut Forester and a team from Groton Utilities. The Plan includes information about forest management and development, soils, and geology, wildlife habitat, osprey platforms, and maps of management areas.

Current management goals and objectives include:

  • Long-term forest management that will help to improve the quality of the forest while protecting the reservoirs, streams, and wetlands
  • Protection of the water quality
  • Protection of soils from erosion
  • Protection from wildfires
  • Improvement of wildlife and bird habitat
  • Control of invasive and non-native species
  • Development of a nursery to produce trees for planting on the watershed

Wildlife Management

Figure 8: Wildlife near Morgan Pond Reservoir

A variety of flora and fauna are indicators of watershed health. Protected watershed land provides habitat. When it abuts other open spaces it can contribute to wildlife corridors and greenways. Groton Utilities watershed land is adjacent to other parcels that are already protected as undeveloped land or open space and forest. These include Connecticut Department of Energy and Environmental Protection Land on Candlewood Hill and parcels on Gungywamp Road in Groton, Avalonia Land Conservancy parcels, Groton Open Space Association (GOSA) properties, Town of Groton open space, and The Copp Family Property.

The Forest Management Plan provides the following strategies with regard to habitat and wildlife:

Mow open field areas to reduce invasive species and promote native vegetation

  • Plant evergreen stands for shade cover and nest sites
  • Install bird boxes -for ducks and bluebirds
  • Release trees that produce seeds, nuts, and fruit for an improved food supply
  • Encourage and support pollinators and the food species they depend on
  • Protect vernal pools with buffer strips- these are unique habitats for breeding amphibians
  • Protect wetland and riparian areas for cover, nesting, and travel corridors

Regulated Migratory Birds

Osprey Program

 Since 1970, Groton Utilities has provided modified utility poles with the Department of Energy and Environmental Protection (DEEP)-designed nesting platforms for osprey. The program was started by the Electric Department in an effort to limit the incidence of power outages due to birds landing on live electric equipment. Modified poles provide alternate locations for nesting and perching. As the Osprey population increased over the decades, additional poles were provided. Both the Electric and Water Departments have been involved in working with the DEEP state wildlife division for banding programs and bird counts.

Figure 9: Osprey nest at Groton Utilities Operations Complex

Connecticut Audubon stewards also monitor nest activity and record the findings in an interactive map on their website. 

In 2011 a pair of bald eagles nested within the watershed of Groton Utilities. Sightings continue though the nest is currently unused.


In an ongoing partnership with the Connecticut Department of Energy and Environmental Protection (CT DEEP) and The United States Geological Survey (USGS), Water Treatment Plant operators from Groton Utilities constructed an American eel collection system. The system is deployed each fall to collect live eels during their migration period. The life cycle of the American eel involves a seasonal migration from fresh water to the ocean and eventually to the Sargasso Sea where they spawn. Without the collection system there is a risk of eels swimming into the intake piping of the Water Treatment Plant; or facing the challenge of swimming downstream, at a time in the season when natural flows are low and sometimes without the necessary overflow from the Poquonnock Reservoir that feeds the head of the Poquonnock River. With the collection system, live eels are measured and counted by CT DEEP before being released downstream, into the Poquonnock River estuary, by hand.