Submitted by the ad hoc Fawn Lake Committee
In the spring of 2015, the Town of Bedford formed the ad hoc Fawn Lake Committee to discuss the long-term use of Fawn Lake and evaluate options for restoration. Committee meetings included representatives from the Conservation Commission, Department of Public Works, Selectmen, Historic Preservation, Bedford residents appointed to the Committee, interested Bedford residents, local press, and the Town’s consultant, CEI, who has lake restoration and dredging experience. Editor’s Note: This report was approved by the Committee in April 2018
Previous evaluations of Fawn Lake by the Town and its consultants have identified increased floating and submerged vegetation, fish kills, impaired canoe and kayak access, reduced lake depth, soft sediment accumulations and slow conversions to swamp-like conditions.
The Committee identified benefits of the Lake which include conservation, open space, recreation, environmental diversity, educational opportunities and historical value.
The Committee recommended Fawn Lake be maintained and improved because of its significant value to the Town of Bedford. A primary goal of the Committee was to identify a conceptual restoration plan to obtain Town approval for appropriating funds to design, permit, and implement restoration of Fawn Lake.
The Committee evaluated the following restoration options to restore lake depth and control aquatic vegetation:
- Hydraulic wet dredging
- Mechanical wet dredging
- Mechanical dry excavation
- Aeration and circulation
- Sub-aqueous vegetation barriers
- Herbicide use
- Water level increase/decrease
- Combinations of the aforementioned
The Committee incorporated the effectiveness of maintenance methods already implemented at Fawn Lake such as herbicide use and hydro-raking into the evaluation process. It also reviewed examples of other lake restoration projects conducted in the Northeast. The Committee identified the following elements for restoration plan design:
- Return approximately 60% of the lake to its original depth,
- Maintain remaining 40% of the lake as shallow cove and shoreline areas for ecological diversity,
- Implement restoration without draining the lake,
- Incorporate dam replacement into the project as the dam is in “poor” condition according to a State Dam Safety evaluation,
- Treat stormwater influent to the lake,
- Maintain and encourage native plant and animal species,
- Incorporate historic elements into the landscape/hardscape restoration,
- Preserve and enhance recreational access for boating, fishing, and skating,
- Avoid the use of current and future herbicides because of the uncertain long-term effects of their use, and
- Prevent fish kills from depleted oxygen conditions.
The Committee recommended the following restoration plan be considered for funding by the Town:
- Utilize wet dredging using hydraulic methods to the original depth of the lake. Removal of soft sediment only,
- Dredge approximately 60% of the northerly section of the lake,
- Preserve existing conditions in the southwest section of the lake to maintain ecological diversity,
- Provide stormwater influent treatment,
- Replace dam where a new outlet control structure can vary the lake water level for increasing overall lake depth, if appropriate, and conducting maintenance activities, and
The recommended restoration plan was selected because it addresses all of the goals established and is the most efficient long-term restoration option evaluated by the Committee. Dredging specific areas of the lake retains ecological diversity, has significantly less initial capital cost than dredging the entire lake, removes unwanted vegetation, preserves historic and natural beauty, restores recreational use, eliminates eutrophication, and lessens the impact to existing fauna.
Hydraulic dredging provides greater long-term value over hydro-raking and significantly less initial capital cost than mechanical dry excavation. Dry excavation is significantly more expensive than hydraulic dredging because in order to maintain water levels in sensitive areas cofferdams or portable dams would be required to hold back the water. Hydro-raking has been used at Fawn Lake and the results were not acceptable as a long-term solution.
Herbicides have been used in the past and the Fawn Lake Committee and the Bedford Conservation Commission are concerned about the unknown long-term effects of current and future herbicide use. Herbicides can be counterproductive as the dead plant material increases sediment accumulation.
Aeration, circulation, and submerged vegetation barriers were not considered to be long-term standalone options. These, however, could be retained in the design process for evaluation as long-term maintenance enhancements. Water level drawdown which would adversely affect shallow habitats was also not a viable solution. Combinations of available techniques could be considered in the future to complement hydraulic dredging.
The recommended restoration plan is in final design; however, the Fawn Lake Committee may seek additional items such as installing features to acknowledge the historical significance of the Bedford Springs area.
The Town and its consultant CEI, Inc. are currently in the process of completing environmental permitting and final dam design in anticipation of funding to be approved at the spring 2019 Annual Town Meeting. Dredging, dam renovation, and site restoration are likely to occur in the summer of 2019 or 2020, depending on available funds.