Lake Peekskill Watershed Management Planning

In response to recurring water quality issues, including a significant cyanobacterial bloom in 2014 that led to prolonged beach closures, the Town of Putnam Valley engaged Princeton Hydro to revise and update the Lake Peekskill Watershed Management Plan. The lake, a small impoundment of Peekskill Hollow Creek, serves as a vital recreational resource for the community. Princeton Hydro’s initial study was structured around three core tasks: (1) analysis of long-term water quality data, (2) development of an updated pollutant budget, and (3) formulation of short- and long-term management strategies.

The analysis revealed a steady increase in conductivity and total phosphorus (TP) concentrations over the past two decades, indicating rising nutrient loads and a shift toward eutrophic conditions. Elevated TP levels were directly linked to increased algal biomass, particularly harmful cyanobacteria producing microcystin-LR, which exceeded safe swimming thresholds in 2014. The updated pollutant budget identified septic system leachate (55%) and stormwater runoff (22%) as the primary sources of phosphorus entering the lake. Internal loading from sediments and atmospheric deposition also contributed to the nutrient burden.

To address these issues, Princeton Hydro proposed a suite of in-lake management interventions focused on the lake’s three public beaches. Recommendations included installing electric water pumps to improve circulation at Carrara’s Beach and ozone/aeration systems at Singer’s and North Beaches to reduce organic buildup and mitigate algal blooms. These nature-based, non-chemical solutions were designed to provide immediate relief while longer-term watershed improvements, such as septic upgrades and stormwater controls, are pursued. The plan emphasized the need for community engagement, regulatory coordination, and sustainable implementation to restore and protect Lake Peekskill’s ecological health and recreational value.

Building on this foundational work, Princeton Hydro was re-engaged in 2022 by the Lake Peekskill Civic Association (LPCA) and the Town of Putnam Valley to provide additional lake management services. The team developed a comprehensive Lake Management Plan aimed at identifying and prioritizing cost-effective green infrastructure and stormwater Best Management Practices (BMPs) for implementation by the Town. The goal was to reduce nutrient loading, improve water quality, mitigate nuisance aquatic vegetation, prevent harmful algal blooms (HABs), and enhance overall stormwater management within the watershed.

This phase of work included a detailed analysis of historical water quality data, a submerged aquatic macrophyte survey, and a field-based water quality assessment. Princeton Hydro also conducted a pollutant removal analysis to evaluate the effectiveness of specific watershed-based management techniques. The resulting plan provided a clear roadmap for reducing annual pollutant loads and minimizing the occurrence and severity of HABs through targeted, science-based interventions. The recommendations were designed to be actionable, scalable, and aligned with the Town’s capacity and resources, reinforcing the long-term commitment to restoring and maintaining the health of Lake Peekskill.