Lake Mohawk Restoration & Management

Princeton Hydro has been working with the Lake Mohawk Country Club (LMCC) since the early 1990s on the management and restoration of Lake Mohawk. The 720-acre polymictic waterbody, which is the main recreational resource for over 2,000 families, experienced year-round harmful algal blooms (HABs) of the cyanobacteria Coelosphaerium prior to Princeton Hydro’s involvement in the lake management and restoration efforts. These blooms even occurred over the winter months under the ice. Princeton Hydro developed a Management Plan to reduce the magnitude, severity, and frequency of these blooms.

Through the implementation of the Plan over the last 29 years, Princeton Hydro oversaw the application of three lake-wide alum treatments, the installation of a destratification aeration system, and the development of an aggressive septic management program. Even before the State of New Jersey banned phosphorous fertilizers in 2004, the LMCC developed a proactive, educational program banning the use of phosphorus fertilizers and installed twelve large sedimentation basins throughout the watershed to reduce non-point source pollution (NPS) entering the lake. Princeton Hydro also designed and installed two alum injection systems into these basins that also inject low-dose concentrations of alum to inactivate phosphorus coming into the lake from storm events.

In 2020 Princeton Hydro assisted the LMCC in securing funds through a State of New Jersey HAB management grant program to assess the overall use of innovative in-lake management actions such as the use of oxidizing algaecides (which kill algae and breakdown cyanotoxins) as well as the application of the nutrient inactivator PhosLock in two of its lakes. These treatments focused on controlling the development of HABs in three near-shore / cove areas that included swimming beaches.

In early 2021, Princeton Hydro also updated the original 1992 Management Plan for Lake Mohawk. Part of this Plan included a detailed analysis of the long-term, 29 year water quality and plankton database for the lake. This analysis documented that Lake Mohawk shifted from being a hyper-eutrophic waterbody to a mildly eutrophic waterbody that is viewed as ecologically acceptable to the community for recreational use. The updated Management Plan identifies a variety of additional watershed measures to further reduce the incoming phosphorus and NPS pollutant loads, with a focus on green infrastructure to further enhance their capacity to remove dissolved forms of phosphorus from watershed based runoff.