An Important Update from the LWTF

Terra Vigilis Studies on Wake Boat Activity: A Task Force Update

January 21, 2025

Several years ago, the Task Force began receiving community inquiries about the environmental impact of wake boats operating in surf mode on Lake Waramaug. In response, the Task Force took two actions:

• Advocacy: In 2020, the Task Force recommended that boats producing large wakes operate at least 300 feet from shore and in water depths of 20 feet or more to minimize potential harm.  A map of this suggested zone can be viewed here [link]. Note this recommendation was based on the information available at the time.

• Research: Recognizing the complexity of the issue, the Task Force committed resources to undertake further study, and to share findings with the community.

The Task Force is a small organization, employing one full-time and one part-time scientist.  As such, the Task Force typically engages expert consultants for complex studies. After careful evaluation, the Task Force identified Terra Vigilis as the best partner for this work. Ultimately, the towns of Washington, Warren, and Kent decided to contract Terra Vigilis directly through the Lake Waramaug Interlocal Commission. Their full report [link] was released on December 16, 2024.

Since Lake Waramaug is primarily fed by Sucker Brook, the Task Force expends considerable resources on monitoring and remediating the brook’s watershed and streambed. As Terra Vigilis was conducting an in-lake study for the three towns, the Task Force further engaged Terra Vigilis to investigate the impact of large waves on the Sucker Brook delta. The findings from that study are available [here].

Key Findings

The Terra Vigilis reports conclude that powerful waves impacting the shore and strong propeller downwash can cause harm to the lake. Powerful waves erode the shoreline and shallows, while propeller downwash scours the lakebed, reducing water clarity and releasing harmful nutrients normally trapped in sediment. These effects are particularly severe in shallow areas like the Sucker Brook delta, where wave energy is dissipated by “scrubbing” the bottom. Preventing erosion and minimizing nutrient release are core goals of the Task Force, as erosion reduces water clarity, and nutrient release increases the risk of toxic algae blooms. The Terra Vigilis findings are consistent with multiple other studies.

Unanswered Questions

• The Terra Vigilis studies compared the impact of wake boats operating in surf mode to ski boats operating on plane, but not to ski boats transitioning to plane, nor to boats engaged in tubing off-plane. 

• The Terra Vigilis studies were not designed to evaluate the potential impact of wake boats operating in surf mode relative to the impact of natural, wind-driven wave action*.

Water Quality Trends

The Task Force has tracked water clarity and phosphorus concentration (both key indicators of lake health) since 1977.  Over this time, the data show a trend of improvement in both clarity and phosphorus concentrations (clarity increases and phosphorus decreases). The Task Force further examined rolling five-year averages of these parameters. These data suggest that water quality was most favorable in the two most recent five-year windows (the last decade split from 2015 to 2019, and 2020 to 2024), although phosphorus concentration in the upper stratum of the lake was relatively consistent from 2000 onwards. When examined on a year-by-year basis, average water clarity slightly decreased from 2015 to 2024, and decreased more sharply from 2020 to 2024. However these year-by-year trends are variable and reflect declines from the exceptionally clear years of 2019 and 2020. Year-by-year phosphorus data suggest slight improvement (decrease) from 2014 to 2024, but a slight worsening (increase) from 2020 to 2024. A more detailed report of this analysis is available [here}.

In sum, the data indicate long term and overall improvement of water quality in Lake Waramaug, with recent years exhibiting high variability and perhaps a slight decline per our indices, albeit from very good levels achieved in the past few decades. With the data available it is unfortunately impossible to ascribe changes in water quality to any one cause, be it wake surfing or other motorized recreational activity, weather events, or property development. 

Conclusion

The Task Force endorses the Terra Vigilis findings, but defers to the three towns to decide whether to implement the Action Items listed in Section 5 ‘Lake Waramaug Impact Management Issues for Consideration’ on pages 24-25 (link). If action is taken, the Task Force strongly suggests particular attention be paid to protecting shallow water areas like the Sucker Brook delta from all wakes.

* The Terra Vigilis Lake Waramaug Shallow Water study did cite work done by Water Environmental Consultants, SC in 2021 as follows: “Wakesurfing vessel wakes exceed wind waves at every site at distances within 500 feet of the vessel sailing line. In contrast, typical cruising vessel wakes do not exceed wind waves at every site, except within a very close proximity to the vessel, i.e., 75 feet.”
Click below for additional information on large wave recreational activities and its potential impact to the lake.

We conserve the lake through outreach, restoration and research.

The Lake Waramaug Task Force is a non-profit organization of volunteers and scientists that provides leadership in restoring and maintaining the ecology and water quality of Lake Waramaug and its watershed. Located in Litchfield County, Connecticut, Lake Waramaug is bordered by the towns of Washington, Warren and Kent. It is a Connecticut Heritage Lake.