algae bloom on Roseland LakeRoseland Lake is considered impaired for its designated use (recreation) due to excessive nutrients, eutrophication and biological indicators. The potential sources are agriculture, waterfowl, and unknown. Read more about the Water Quality of Roseland Lake.

Roseland Lake is a primary source of drinking water for the Town of Putnam and limited areas of Woodstock. The lake suffers from chronic algae blooms.

Algae imparts an undesirable taste to drinking water. The Town of Putnam treats the lake with copper sulfate to control the algae. Trout and other water organisms are sensitive to even small concentrations of copper. Also, copper sulfate treatment causes existing algae blooms to die and sink to the bottom of the lake, and then decay, which can result in oxygen depletion. Therefore, preventing algae growth in the first place would be better than periodic treatment with chemicals.


There are no permitted industrial discharges to Roseland Lake. No specific storm drain outlet issues have been identified above Roseland Lake in the area closest to tributary streams, although there are some Areas of Concern.

That means that the main problem for Roseland Lake what is called "nonpoint source pollution." The term"nonpoint" refers to the fact that the pollution is not coming out of a specific discharge point like a pipe. Instead, it comes from diffuse sources, as rainfall and/or snowmelt move over and through the ground.

A large quantity of surface water moving over the land (e.g., during a heavy rainfall) is called "stormwater." "Stormwater runoff" is water that runs off across the land instead of seeping into the ground. It usually flows downhill to the nearest body of water, and is not treated in any way.

Stormwater runoff can carry fertilizers, pesticides, pathogens, sand, sediment, salt, heavy metals and petroleum products into the lake. Large quantities of unregulated stormwater flow can cause erosion and sedimentation. Erosion and sedimentation can increase nutrient loading that causes eutrophication, which in turn contributes to algae blooms. Sedimentation can also interfere with hatching of fish and amphibian eggs. Stormwater runoff during a major rain event can also cause rapid temperature changes in parts of the lake.

Specific activities that can contribute to pollution at Roseland Lake include the following:

  • Runoff from agricultural operations (like growing crops or raising cows) upstream can contain animal waste by products, fertilizers and pesticides. The Woodstock Golf Course uses pesticides and fertilizers. They are located to the west of Roseland Lake. One of the fairways drains into an intermittent stream channel that empties into Roseland Lake.
  • Housing and residential development upstream or around the lake can increase nutrient loading due to lawn care practices, pet waste, loss of vegetated buffers, and malfunctioning septic systems.
  • Timber harvesting and land clearing during construction can result in soil erosion. The slopes on the southeastern side of Roseland Lake are very steep. When stripped of ground cover, heavy rainfall creates gullies, carrying dirt and sand into the lake.
  • An increase in impervious surfaces (like paved driveways) can keep water from slowly soaking into the ground, resulting in sheet flow of water that can carry pollutants and sediment with it.
  • Canada geese can contribute to water quality impairment. Large numbers of migratory and over-wintering populations of waterfowl do congregate on the lake. However, the Muddy Brook and Little River Water Quality Improvement Plan concluded that Canada geese do not stay long enough at Roseland Lake to be of concern. So far, there are no resident populations here. If future populations do become established, their fecal material could further increase nutrient loading in the lake.




Roseland Lake is part of the Little River watershed. Volunteers and officials from the towns of Putnam and Woodstock and the State of CT DEEP have been working together with environmental protection and conservation agencies and land trusts, residents and businesses to develop a plan to protect the Putnam and Woodstock water supplies, which includes the Little River Watershed.

A management plan was developed by a local volunteer team during a nearly year-long process to protect the Little River watershed which supplies drinking water for much of the Town of Putnam and public water supply wells in Woodstock. The plan addresses the lack of hard data and the need to mitigate known potential contamination sources. Major plan elements included: a comprehensive evaluation of the watershed, agricultural best practices, protection of key watershed lands, education and outreach, and a focus on both Roseland Lake and Muddy Pond waterbodies.

A Plan summary is posted on Town of Putnam website (under Water and Sewer Dept, Information) at: (Source: CT Nonpoint Source Management Program, 2005 Annual Report, CT DEP, November 2006)


The Muddy Brook and Little River Water Quality Improvement Plan recommended the following measures to help protect Roseland Lake.

    • Establish/increase/maintain vegetated buffers: on the lake shores. Note that in 2012, a rain garden was installed along the stream by the Woodstock Golf Course to provide a vegetative buffer.
    • Avoid disturbing highly erodible soils. Even though the Town of Woodstock regulations only require stormwater controls for construction projects involving more than 2.5 acres, Roseland Lake is small enough to be negatively impacted by smaller projects.
    • Manage crop land cover. Develop and continue sound management practices. Farmers can voluntarily implement best management practices to reduce agricultural runoff. For example, farms can apply for a Section 319 NPS grant for innovative manure injection application on sensitive agricultural lands.
    • Minimize and manage fertilizer and pesticide application: Develop and continue sound management practices. Farmers can voluntarily implement best management practices to reduce agricultural runoff. Implement green lawn care practices to minimize or eliminate the use of fertilizers and pesticides.
    • Maintain and monitor septic systems, and repair as needed.
    • Scoop Poop: remove pet waste from areas near the lake.
    • Support preservation of key parcels.
      • The Little River was granted Greenway status in 2006. This status is jointly applied by the Towns of Woodstock and Putnam as part of a natural resource protection strategy.
      • Although some of the land surrounding Roseland Lake is not developed, currently only Roseland Park and the Wyndham Land Trust Little River Preserve are considered "protected" open space.
      • The Zeelandia parcel is under PA-490, and the owners plan to put a conservation easement on it with a local land trust.


The following additional recommendations apply to the watershed as a whole.

  • Form a local watershed/source water protection team to evaluate plan implementation progress and modify it as needed. As of 2014, a formal standing committee had not been formed. However, some watershed stakeholders continue efforts to fulfill the recommendations contained in the plan.
  • Assess threats and develop strategies to address those threats.
  • Monitor water quality.
  • Establish thresholds for nutrients, eutrophication and biological indicators. Set goals to improve water quality to the target Class AA.
  • Implement best management practices that target nutrient Nonpoint Source pollution.
  • Use town zoning to minimize impacts from development.
  • Establish local watershed protection regulations.
  • Address stormwater issues (Areas of Concern) and implement best management practices and controls: e.g., plant vegetated swales to enhance infiltration, minimize impervious surfaces, minimize steep slopes, control erosion during construction, upgrade stormwater management facilities, treat stormwater as appropriate, etc.
  • Avoid introducing invasive species
  • Evaluate, control and remove invasive plant species.
    • Note: The CT DEEP treated Phragmites clumps growing on Roseland Lake in 2005 (?), and again in September of 2014.
    • Dredge or excavate out dead and dislodged Phragmites rhizomes that trap 'floatables' carried by wind and waves (Note: This would require a permit from the Army Corps of Engineers under Section 404 of the Clean Water Act.)
  • Prevent the introduction of invasive aquatic species (aquatic hitchhikers.)
  • Take measures to prevent the establishment of resident Canada Geese populations.
  • Discourage feeding of waterfowl.
  • Hold and participate in household hazardous waste collection days to prevent illegal disposal of hazardous chemicals.
  • Inspect underground fuel storage tanks and remove them if they are failing.
  • Offer targeted periodic public outreach and education to increase environmental awareness, including interpretive signage and events.



Roseland Lake Nutrients Loads Modeling Project

Roseland Lake is located in Woodstock, CT.  The lake is in the Little River sub-regional watershed which drains into the Quinebaug River in Putnam, CT.  Between Roseland Lake and the Quinebaug River, the Town of Putnam withdraws and treats water from Little River to use as a public drinking water source.

Roseland Lake and several stream segments in the Little River watershed are not meeting Connecticut water quality standards.  In 2009, ECCD staff investigated possible causes and prepared a watershed-based plan to address those issues.  One recommendation of the plan was to study the sources of nutrients impacting water quality in Roseland Lake and determine how many of the water quality issues were from current watershed runoff, and how many were influenced by legacy nutrients deposited in the lake over a long time period.

In the summer months, when water in the the lake is warmer at the surface, the lake develops temperature layers.  Colder water in the bottom of the lake becomes anoxic, or has no dissolved oxygen in it. When this happens, it shifts the chemistry at the bottom of the lake and nutrients normally stored in the lake sediments dissolve into the water. Are these nutrients a major source of summer algae blooms in the lake?

Beginning in 2015, ECCD staff, with the assistance of volunteers from The Last Green Valley Volunteer Water Quality Monitoring Program, began collecting and analyzing water samples from the lake and the streams that flow into it.  We are investigating if the nutrients from the bottom of the lake are supporting algae blooms at the surface.  Algae blooms degrade the  habitat in the lake as well as increase the cost of water treatment downstream.  There are algae that  make the water taste and smell bad.  Certain algae may also release toxins into the water.

The data we are collecting will be used in a mathematical model to calculate the watershed versus the in-lake nutrient contributions to the algae problems in Roseland Lake.  Once the major sources of nutrients are identified, ECCD will develop plans to effectively reduce those sources of nutrients.

This project is being funded in part by the Connecticut Department of Energy & Environmental Protection through a United States Environmental Protection Agency Clean Water Act Section 319 Nonpoint Source Grant and the Putnam Water Pollution Control Authority.  Additional project partners include the CT Department of Public Health Drinking Water Division, Dr. Mauri Pelto of Nichols College, the Woodstock Conservation Commission and CME Associates.

Project Updates

The Roseland Lake Management Plan can be found here, as well as three appendices to the plan: Roseland Lake Nutrient Monitoring QAPP, Roseland Lake Sediment Sampling QAPP and Roseland Lake Nutrient Modeling QAPP. The Roseland Lake Management Plan Executive Summary, which includes the roles and responsibilities of project partners, can be found here.

A review of previous water quality studies in Roseland Lake was compiled and submitted to CT DEEP.  Click here to download this report.

A workshop focused on algae control in lakes took place on April 6, 2016.  Click here to download a workshop agenda.

To measure the legacy load of phosphorus available for recycling in the lake during summer anoxic conditions, bottom sediment sampling was a required element of this project. Photodocumentation and the report of the results are available here.

ECCD staff, with assistance from volunteers with The Last Green Valley Water Quality monitoring program, have completed the water quality sampling work in Roseland Lake and the tributaries that flow into the lake.  This included sampling the bottom sediments to determine the amount of legacy phosphorus stored in the sediments.  The process of data review is complete.