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It has a watershed area of approximately 32 square miles, encompassing parts of six municipalities. The watershed is quite varied in many respects. At nearly 14 miles in length along the north-south axis, elevations range from sea level up to 630’. Because of its glacial geology, the topography includes low hills, while the main river valley features steep escarpments. The development patterns essentially divide the watershed in two: the developed southern and eastern portions of the watershed, and the rural headwaters to the north and west. Princeton Hydro was contracted by Fairfield County, CT to develop the Mill River Watershed Management Plan (WMP). The Fairfield Conservation Commission, part of the municipal government for the Town of Fairfield, applied for a Clean Water Act Section 319(h) Nonpoint Source Program grant with CT DEEP to help address the TMDL and other nonpoint source (NPS) pollutant loading and stormwater management concerns in the Mill River. The grant was awarded for the development of this Watershed Management Plan (WMP). Princeton Hydro worked with project partners, including Connecticut DEEP, Harbor Watch, Trout Unlimited, Fairfield Shellfish Commission, FairPLAN, Mill River Wetland Committee, and Lake Hills Association, throughout the watershed planning process. Mill River does not meet some of the water quality standards or designated uses. For example, in 2004 Mill River was added to the 303(d) List of Impaired Waterbodies, which is named after a section of the Clean Water Act that mandates tracking and reporting of impaired waters, for exceeding the standards associated with indicator bacteria. Mill River has had problems with excessive concentrations of Escherichia coli, more commonly E. coli. The WMP was primarily intended to provide a path to improve water quality throughout the watershed. The plan followed the requirements for the Environmental Protection Agency’s watershed-based plans (WBP) that addresses nine specific elements. This type of plan therefore covered a wide range of topics including identification of water quality problems, determining the cause of those problems, identifying measures to correct the problems, securing the technical and financial assistance to implement the plan, and developing criteria, schedules, and a monitoring program to track progress. Throughout this process, Princeton Hydro routinely met with stakeholders to define their vision and refine the plan to meet the goals and objectives in an achievable manner. [gallery columns="2" link="none" size="full" ids="19552,19551"] [post_title] => Mill River Watershed Management Plan [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => mill-river-watershed-management-plan [to_ping] => [pinged] => [post_modified] => 2026-04-07 18:21:59 [post_modified_gmt] => 2026-04-07 18:21:59 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=19550 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [1] => WP_Post Object ( [ID] => 19549 [post_author] => 1 [post_date] => 2026-04-07 18:08:34 [post_date_gmt] => 2026-04-07 18:08:34 [post_content] => Princeton Hydro was contracted by the Warren Hills School Regional School District (WHRSD) to provide a completed dam inspection, dam breach scenario, hydrologic and hydraulic (H&S) modeling, inundation analysis, and hazard classification for the Warren Hills Dam. Located on a tributary of Pohatcong Creek in Washington Township, Warren County, the earthen dam was constructed circa the 1930s and was reconstructed in the 1990s involving spillway repairs. Upon the completion of Princeton Hydro’s careful evaluation of alternative assessments contained in the inspection report, the Warren Hill School District made the decision to seek dam removal. The unsatisfactory condition rating contained in the inspection report, as well as the need for WHRSD to us an adjacent structure for academic activities in Fall 2020, contributed to the decision. Princeton Hydro was then contracted to facilitate the dam decommissioning and throughout the project development, performed the site survey for the identification of hazardous materials; wetland delineation; site investigation; and sediment sampling, analysis, and probing. Princeton Hydro preformed a stream assessment of the channels upstream of the impoundment, and the downstream mill race. Sediment probes were completed throughout the impoundment to determine the depth of unconsolidated material (sediment) and provide a general understanding of the substrate encountered at refusal depth. The proposed channel within the impoundment reflected existing upstream reaches, the anticipated natural channel type, and the assumed pre-dam channel: a boulder dominated cascade, approximately 12 feet wide, up to two-foot max depth, and 10% slope, with occasional/irregular boulder steps. As part of the engineering design, Princeton Hydro also conducted planning, permitting, and construction management and oversight. The completed design involved sediment excavation and onsite storage, as well as stable channel creation. Through an accelerated schedule Princeton Hydro worked to complete the permitting and dam removal before the start of the 2019 school year. [post_title] => Warren Hills Dam Decommissioning [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => warren-hills-dam-decommissioning [to_ping] => [pinged] => [post_modified] => 2026-04-07 18:08:34 [post_modified_gmt] => 2026-04-07 18:08:34 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=19549 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [2] => WP_Post Object ( [ID] => 19292 [post_author] => 1 [post_date] => 2026-03-06 13:46:46 [post_date_gmt] => 2026-03-06 13:46:46 [post_content] => The Goethals Bridge Replacement Project resulted in unavoidable impacts to 4.929 acres of wetlands and open water associated with the Arthur Kill, requiring the creation of 15.39 acres of mudflat, low marsh, high marsh, and scrub/shrub habitat; and preservation of 3.91 acres of existing low marsh/high marsh and open water habitat. Princeton Hydro worked with the United States Army Corps of Engineers (USACE) – New York District and the New York State Department of Environmental Conservation (NYSDEC) on the development of an acceptable monitoring program that was implemented in 2019. As stipulated in the NYSDEC-issued permit, the monitoring program had to follow the New York State Salt Marsh Restoration and Monitoring Guidelines (Guidelines) established in 2000. Working closely with USACE and NYSDEC and following the program specified within the Guidelines, Princeton Hydro established five transects and eighteen associated 1m2 quadrat locations along the five transects. Each transect represented a cross section of the various ecological communities present between Old Place Creek and the upper extent of the mitigation site. The ecological communities monitored across each transect included low marsh, high marsh, transitional zones between low marsh and high marsh, and scrub/shrub, respectively. [gallery link="none" columns="2" ids="19307,19305"] The following metrics were calculated within each 1m2 quadrat: overall percent cover and species composition comprising the observed percent cover. Within each 1m2 quadrat, a 0.25m2 portion of the quadrat was analyzed for stem density and plant height as outlined within the Guidelines. Additionally, the entire mitigation site was investigated for the presence of invasive species with subsequent mapping developed and incorporated into an adaptive management plan. This was then implemented to address the presence of common reed (Phragmites australis). Annual monitoring reports were prepared and submitted to both USACE and NYSDEC detailing the results of the monitoring effort with a focus on the established transects and 1m2 quadrats along each transect. A section of the reports was dedicated to the development of an adaptive management plan to ensure the mitigation site satisfied the requisite 85% vegetative cover comprised of desirable, native species. [post_title] => NYSDEC Wetland Monitoring - Old Place Creek Mitigation Site [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => nysdec-wetland-monitoring-old-place-creek-mitigation-site [to_ping] => [pinged] => [post_modified] => 2026-03-06 13:46:46 [post_modified_gmt] => 2026-03-06 13:46:46 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=19292 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [3] => WP_Post Object ( [ID] => 19291 [post_author] => 1 [post_date] => 2026-03-06 13:38:57 [post_date_gmt] => 2026-03-06 13:38:57 [post_content] => 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. [post_title] => Lake Peekskill Watershed Management Planning [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => lake-peekskill-watershed-management-planning [to_ping] => [pinged] => [post_modified] => 2026-03-06 13:38:57 [post_modified_gmt] => 2026-03-06 13:38:57 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=19291 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [4] => WP_Post Object ( [ID] => 19287 [post_author] => 1 [post_date] => 2026-02-06 13:31:30 [post_date_gmt] => 2026-02-06 13:31:30 [post_content] => The City of Lambertville contracted Princeton Hydro and WSP to evaluate Lambertville’s need for, and ability to create, a fee‑based Stormwater Utility. Lambertville faces stormwater management issues primarily due to its geographic and infrastructural characteristics. Situated along the Delaware River, the city is prone to flooding, which is exacerbated by aging and inadequate stormwater infrastructure. Dense urban development results in a high percentage of impervious surfaces, such as roads and buildings, that prevent proper absorption of rainwater, leading to increased runoff and strain on existing drainage systems. [caption id="attachment_19301" align="aligncenter" width="770"] Sample of single-family residential parcels and median impervious surface area[/caption] Lambertville’s stormwater infrastructure includes more than 530 identified stormwater inlets, a series of aging culverts, and miles of stormwater conveyance piping—much of it in unknown condition—with many structures serving as components of cross‑jurisdictional systems, all paired with repeated devastation from flooding. The project team completed a Lambertville Stormwater Utility Feasibility Study, which included the following components: Programmatic and Organizational Review: Evaluation of existing stormwater infrastructure operation and maintenance practices, as well as current program organization and administration. Gaps and Funding Analysis and Future Program Needs: Review and presentation of recent and projected capital project needs and baseline costs provided by Lambertville, along with an assessment of current revenue sources. Land Cover Analysis, Digitization of Impervious Cover, and Equity of Current Costs: Digitization and evaluation of land cover data based on the potential use of an Equivalent Residential Unit (ERU) rate structure and the quantification of billing units. Assessment of the equity of current stormwater costs and the potential impact of a fee‑based stormwater utility on different landowner categories. [caption id="attachment_19297" align="aligncenter" width="888"] Sankey Diagram highlighting the shift from current tax revenue to a stormwater utility fee.[/caption] User Fee Rate Options and Summary: Evaluation of how revenue generation might shift from a general‑fund, tax‑based model to a fee‑based model, including a summary of available rate structures designed to balance equity, cost, and administrative ease. Policy Development and Legislation Review: Examination of the policy framework for delivering stormwater management services under a utility model, including policies related to extent of service, billing, and funding. Topics included mission and program priorities, level of service, organizational structure, and credit policy. Public Outreach & Stakeholder Engagement: Formation and facilitation of a Stormwater Focus Group composed of key stakeholders, as well as hosting a public meeting to gather feedback, ensure transparency, and support community participation. [gallery columns="2" link="none" ids="19300,19299"] Funding for the Lambertville Stormwater Utility Feasibility Study was provided through a grant from the New Jersey League of Conservation Voters Education Fund. [post_title] => City of Lambertville - Stormwater Utility Feasibility Study [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => city-of-lambertville-stormwater-utility-feasibility-study [to_ping] => [pinged] => [post_modified] => 2026-04-08 16:27:08 [post_modified_gmt] => 2026-04-08 16:27:08 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=19287 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [5] => WP_Post Object ( [ID] => 19281 [post_author] => 1 [post_date] => 2026-02-05 19:57:58 [post_date_gmt] => 2026-02-05 19:57:58 [post_content] => The U.S. Army Corps of Engineers, New York District (USACE), in partnership with the New Jersey Department of Environmental Protection (NJDEP), conducted a comprehensive study to identify ecosystem restoration and flood-damage-reduction solutions for the Millstone River Basin in New Jersey. Project stakeholders included the U.S. Geological Survey, the USDA Natural Resources Conservation Service, Mercer and Middlesex Counties, Princeton University, and the Stony Brook–Millstone Watershed Association. During the study, Carnegie Lake, a freshwater impoundment of the Millstone River located in Mercer and Middlesex Counties, was identified as a significant natural resource within the watershed. As the project’s lead agency, USACE contracted Princeton Hydro to develop a detailed lake and watershed restoration plan for Carnegie Lake. The Carnegie Lake and Watershed Restoration Plan focused on three primary objectives. First, it involved collecting a wide range of site‑specific in‑lake and watershed data. Second, it quantified the hydrologic and non‑point‑source pollutant budgets for the lake, including total suspended solids and the nutrients nitrogen and phosphorus. Third, it used the findings from the first two objectives to develop a comprehensive lake and watershed restoration plan. The first objective was completed in 2003, during which extensive data were collected throughout the growing season. A major component of this effort was a detailed bathymetric survey that measured water depths and the volume of unconsolidated sediments. Additional tasks included collecting physical, chemical, and biological in‑lake data; conducting macrophyte and fisheries surveys; and collecting and analyzing baseline and stormwater samples. Hydrologic and pollutant budgets for Carnegie Lake and its watershed were then developed using standardized and widely accepted models calibrated with the collected baseline and stormwater data. These budgets informed water‑quality models used to predict in‑lake conditions under various climatic and pollutant‑loading scenarios. All water‑quality and watershed data, along with model results, were used to evaluate and prioritize feasible, cost‑effective in‑lake and watershed management techniques aimed at improving water quality and reducing pollutant loads. The project was finalized in March 2005. [gallery link="none" ids="19279,19277,19276"] [post_title] => Carnegie Lake Phase I Lake and Watershed Restoration Plan [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => carnegie-lake-phase-i-lake-and-watershed-restoration-plan [to_ping] => [pinged] => [post_modified] => 2026-04-08 16:26:56 [post_modified_gmt] => 2026-04-08 16:26:56 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=19281 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [6] => WP_Post Object ( [ID] => 19075 [post_author] => 1 [post_date] => 2026-01-25 03:46:18 [post_date_gmt] => 2026-01-25 03:46:18 [post_content] => In 2007, the NJ Department of Environmental Protection (NJDEP) approved Union Township as the Lead Planning Agency for the creation of the Sidney Brook Watershed Protection Plan (WPP), with Princeton Hydro as the subcontractor. The project partners include: Union and Franklin Townships, Hunterdon County, New Jersey Water Supply Authority (NJWSA), and NJDEP. The project was funded under the Clean Water Act 319(h) program. WWPs are critical planning documents that outline the management of watersheds to comply with water quality standards and use designation, as well as protect resources and mitigate impairments. Sidney Brook is a Trout Maintenance Category One (C1) stream, which flows into the South Branch of the Raritan River. The 10 square mile watershed has a variety of rural and urban land uses which have contributed to degradation in stream function. Portions of this watershed lie within the Highlands Preservation area and Highlands Planning area, which affects future development. WPPs consist of two main components: an assessment of the watershed and a series of management actions. The assessment included a review of relevant GIS data, regulations, an exhaustive water quality study, fishery and other biological surveys, and pollutant and hydrology modeling. These were used to ascertain the function of the watershed. The impairments identified through the WPP process were recommended to be addressed through a series of management actions and BMPs. These actions are discussed in general terms and also through the inclusion of 40 specific project sites and project concepts forwarded by both Princeton Hydro and NJWSA. Additional implementation guidance was also provided to ensure the WPP is fully implemented. While the watershed earned its C1 status, there were also documented impairments in function, including thermal impacts, excessive nutrient loading, and erosion/ sedimentation. Implementation of the recommended projects was initiated by NJWSA with a demonstration project completed in 2012. Princeton Hydro has worked with Union Township to work to secure additional 319(h) grants to implement the installation of 15 discrete BMPs at four project sites. The WPP was key in seeking this funding. This WPP was formally approved in 2012 and at the time, was one of just 18 approved plans statewide. [post_title] => Sidney Brook Watershed Protection Plan [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => sidney-brook-watershed-protection-plan [to_ping] => [pinged] => [post_modified] => 2026-01-13 00:00:57 [post_modified_gmt] => 2026-01-13 00:00:57 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=19075 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [7] => WP_Post Object ( [ID] => 19070 [post_author] => 1 [post_date] => 2026-01-25 03:21:37 [post_date_gmt] => 2026-01-25 03:21:37 [post_content] => Colonial Lake is located within Colonial Lake Park, a 2.1-acre public park in the highly developed Lawrence Township. The lake shows varying degrees of bank erosion. To address these issues, Lawrence Township secured a grant from the New Jersey Department of Environmental Protection to restore 800 linear feet of shoreline using native vegetation and sustainable practices. In the winter of 2024, Princeton Hydro was contracted to provide consulting services for shoreline stabilization and to design living shorelines along sections of Colonial Lake. Princeton Hydro conducted a comprehensive shoreline evaluation, classifying the observed erosion into the following categories and applying targeted stabilization strategies for each:
The Mill River Watershed is located in Fairfield County in southwestern Connecticut. It has a watershed area of approximately 32 square miles, encompassing parts of six municipalities. The watershed is quite varied in many respects. At nearly 14 miles in length along the north-south axis, elevations range from sea level up to 630’. Because of its glacial geology, the topography includes low hills, while the main river valley features steep escarpments. The development patterns essentially divide the watershed in two: the developed southern and eastern portions of the watershed, and the rural headwaters to the north and west.
Princeton Hydro was contracted by Fairfield County, CT to develop the Mill River Watershed Management Plan (WMP). The Fairfield Conservation Commission, part of the municipal government for the Town of Fairfield, applied for a Clean Water Act Section 319(h) Nonpoint Source Program grant with CT DEEP to help address the TMDL and other nonpoint source (NPS) pollutant loading and stormwater management concerns in the Mill River. The grant was awarded for the development of this Watershed Management Plan (WMP). Princeton Hydro worked with project partners, including Connecticut DEEP, Harbor Watch, Trout Unlimited, Fairfield Shellfish Commission, FairPLAN, Mill River Wetland Committee, and Lake Hills Association, throughout the watershed planning process.
Mill River does not meet some of the water quality standards or designated uses. For example, in 2004 Mill River was added to the 303(d) List of Impaired Waterbodies, which is named after a section of the Clean Water Act that mandates tracking and reporting of impaired waters, for exceeding the standards associated with indicator bacteria. Mill River has had problems with excessive concentrations of Escherichia coli, more commonly E. coli.
The WMP was primarily intended to provide a path to improve water quality throughout the watershed. The plan followed the requirements for the Environmental Protection Agency’s watershed-based plans (WBP) that addresses nine specific elements. This type of plan therefore covered a wide range of topics including identification of water quality problems, determining the cause of those problems, identifying measures to correct the problems, securing the technical and financial assistance to implement the plan, and developing criteria, schedules, and a monitoring program to track progress. Throughout this process, Princeton Hydro routinely met with stakeholders to define their vision and refine the plan to meet the goals and objectives in an achievable manner.
Princeton Hydro was contracted by the Warren Hills School Regional School District (WHRSD) to provide a completed dam inspection, dam breach scenario, hydrologic and hydraulic (H&S) modeling, inundation analysis, and hazard classification for the Warren Hills Dam. Located on a tributary of Pohatcong Creek in Washington Township, Warren County, the earthen dam was constructed circa the 1930s and was reconstructed in the 1990s involving spillway repairs.
Upon the completion of Princeton Hydro’s careful evaluation of alternative assessments contained in the inspection report, the Warren Hill School District made the decision to seek dam removal. The unsatisfactory condition rating contained in the inspection report, as well as the need for WHRSD to us an adjacent structure for academic activities in Fall 2020, contributed to the decision.
Princeton Hydro was then contracted to facilitate the dam decommissioning and throughout the project development, performed the site survey for the identification of hazardous materials; wetland delineation; site investigation; and sediment sampling, analysis, and probing. Princeton Hydro preformed a stream assessment of the channels upstream of the impoundment, and the downstream mill race. Sediment probes were completed throughout the impoundment to determine the depth of unconsolidated material (sediment) and provide a general understanding of the substrate encountered at refusal depth. The proposed channel within the impoundment reflected existing upstream reaches, the anticipated natural channel type, and the assumed pre-dam channel: a boulder dominated cascade, approximately 12 feet wide, up to two-foot max depth, and 10% slope, with occasional/irregular boulder steps. As part of the engineering design, Princeton Hydro also conducted planning, permitting, and construction management and oversight.
The completed design involved sediment excavation and onsite storage, as well as stable channel creation. Through an accelerated schedule Princeton Hydro worked to complete the permitting and dam removal before the start of the 2019 school year.
The Goethals Bridge Replacement Project resulted in unavoidable impacts to 4.929 acres of wetlands and open water associated with the Arthur Kill, requiring the creation of 15.39 acres of mudflat, low marsh, high marsh, and scrub/shrub habitat; and preservation of 3.91 acres of existing low marsh/high marsh and open water habitat. Princeton Hydro worked with the United States Army Corps of Engineers (USACE) – New York District and the New York State Department of Environmental Conservation (NYSDEC) on the development of an acceptable monitoring program that was implemented in 2019. As stipulated in the NYSDEC-issued permit, the monitoring program had to follow the New York State Salt Marsh Restoration and Monitoring Guidelines (Guidelines) established in 2000. Working closely with USACE and NYSDEC and following the program specified within the Guidelines, Princeton Hydro established five transects and eighteen associated 1m2 quadrat locations along the five transects. Each transect represented a cross section of the various ecological communities present between Old Place Creek and the upper extent of the mitigation site. The ecological communities monitored across each transect included low marsh, high marsh, transitional zones between low marsh and high marsh, and scrub/shrub, respectively.
The following metrics were calculated within each 1m2 quadrat: overall percent cover and species composition comprising the observed percent cover. Within each 1m2 quadrat, a 0.25m2 portion of the quadrat was analyzed for stem density and plant height as outlined within the Guidelines. Additionally, the entire mitigation site was investigated for the presence of invasive species with subsequent mapping developed and incorporated into an adaptive management plan. This was then implemented to address the presence of common reed (Phragmites australis). Annual monitoring reports were prepared and submitted to both USACE and NYSDEC detailing the results of the monitoring effort with a focus on the established transects and 1m2 quadrats along each transect. A section of the reports was dedicated to the development of an adaptive management plan to ensure the mitigation site satisfied the requisite 85% vegetative cover comprised of desirable, native species.
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.
The City of Lambertville contracted Princeton Hydro and WSP to evaluate Lambertville’s need for, and ability to create, a fee‑based Stormwater Utility. Lambertville faces stormwater management issues primarily due to its geographic and infrastructural characteristics. Situated along the Delaware River, the city is prone to flooding, which is exacerbated by aging and inadequate stormwater infrastructure. Dense urban development results in a high percentage of impervious surfaces, such as roads and buildings, that prevent proper absorption of rainwater, leading to increased runoff and strain on existing drainage systems.
Lambertville’s stormwater infrastructure includes more than 530 identified stormwater inlets, a series of aging culverts, and miles of stormwater conveyance piping—much of it in unknown condition—with many structures serving as components of cross‑jurisdictional systems, all paired with repeated devastation from flooding.
The project team completed a Lambertville Stormwater Utility Feasibility Study, which included the following components:
Funding for the Lambertville Stormwater Utility Feasibility Study was provided through a grant from the New Jersey League of Conservation Voters Education Fund.
The U.S. Army Corps of Engineers, New York District (USACE), in partnership with the New Jersey Department of Environmental Protection (NJDEP), conducted a comprehensive study to identify ecosystem restoration and flood-damage-reduction solutions for the Millstone River Basin in New Jersey. Project stakeholders included the U.S. Geological Survey, the USDA Natural Resources Conservation Service, Mercer and Middlesex Counties, Princeton University, and the Stony Brook–Millstone Watershed Association.
During the study, Carnegie Lake, a freshwater impoundment of the Millstone River located in Mercer and Middlesex Counties, was identified as a significant natural resource within the watershed. As the project’s lead agency, USACE contracted Princeton Hydro to develop a detailed lake and watershed restoration plan for Carnegie Lake.
The Carnegie Lake and Watershed Restoration Plan focused on three primary objectives. First, it involved collecting a wide range of site‑specific in‑lake and watershed data. Second, it quantified the hydrologic and non‑point‑source pollutant budgets for the lake, including total suspended solids and the nutrients nitrogen and phosphorus. Third, it used the findings from the first two objectives to develop a comprehensive lake and watershed restoration plan.
The first objective was completed in 2003, during which extensive data were collected throughout the growing season. A major component of this effort was a detailed bathymetric survey that measured water depths and the volume of unconsolidated sediments. Additional tasks included collecting physical, chemical, and biological in‑lake data; conducting macrophyte and fisheries surveys; and collecting and analyzing baseline and stormwater samples.
Hydrologic and pollutant budgets for Carnegie Lake and its watershed were then developed using standardized and widely accepted models calibrated with the collected baseline and stormwater data. These budgets informed water‑quality models used to predict in‑lake conditions under various climatic and pollutant‑loading scenarios. All water‑quality and watershed data, along with model results, were used to evaluate and prioritize feasible, cost‑effective in‑lake and watershed management techniques aimed at improving water quality and reducing pollutant loads.
The project was finalized in March 2005.
In 2007, the NJ Department of Environmental Protection (NJDEP) approved Union Township as the Lead Planning Agency for the creation of the Sidney Brook Watershed Protection Plan (WPP), with Princeton Hydro as the subcontractor. The project partners include: Union and Franklin Townships, Hunterdon County, New Jersey Water Supply Authority (NJWSA), and NJDEP. The project was funded under the Clean Water Act 319(h) program. WWPs are critical planning documents that outline the management of watersheds to comply with water quality standards and use designation, as well as protect resources and mitigate impairments.
Sidney Brook is a Trout Maintenance Category One (C1) stream, which flows into the South Branch of the Raritan River. The 10 square mile watershed has a variety of rural and urban land uses which have contributed to degradation in stream function. Portions of this watershed lie within the Highlands Preservation area and Highlands Planning area, which affects future development. WPPs consist of two main components: an assessment of the watershed and a series of management actions. The assessment included a review of relevant GIS data, regulations, an exhaustive water quality study, fishery and other biological surveys, and pollutant and hydrology modeling. These were used to ascertain the function of the watershed.
The impairments identified through the WPP process were recommended to be addressed through a series of management actions and BMPs. These actions are discussed in general terms and also through the inclusion of 40 specific project sites and project concepts forwarded by both Princeton Hydro and NJWSA. Additional implementation guidance was also provided to ensure the WPP is fully implemented.
While the watershed earned its C1 status, there were also documented impairments in function, including thermal impacts, excessive nutrient loading, and erosion/ sedimentation. Implementation of the recommended projects was initiated by NJWSA with a demonstration project completed in 2012. Princeton Hydro has worked with Union Township to work to secure additional 319(h) grants to implement the installation of 15 discrete BMPs at four project sites. The WPP was key in seeking this funding. This WPP was formally approved in 2012 and at the time, was one of just 18 approved plans statewide.
Colonial Lake is located within Colonial Lake Park, a 2.1-acre public park in the highly developed Lawrence Township. The lake shows varying degrees of bank erosion. To address these issues, Lawrence Township secured a grant from the New Jersey Department of Environmental Protection to restore 800 linear feet of shoreline using native vegetation and sustainable practices. In the winter of 2024, Princeton Hydro was contracted to provide consulting services for shoreline stabilization and to design living shorelines along sections of Colonial Lake.
Princeton Hydro conducted a comprehensive shoreline evaluation, classifying the observed erosion into the following categories and applying targeted stabilization strategies for each:
Following the visual assessment, in addition to the development of engineering plans and planting schedules focused on a native plant palette, the collected data was used to generate conceptual plans to visually aid in the understanding of the proposed stabilization measures.
Finally, Princeton Hydro assisted the regulatory compliance by securing all necessary permits. Construction was successfully completed in the fall of 2025. Princeton Hydro continues to collaborate with the Township to develop educational signage aimed at engaging residents and visitors, highlighting the Township’s commitment to improving water quality and promoting ecological health.
From 2001 through 2002 Princeton Hydro collected the necessary field data such as in-situ, bathymetric, and discrete (both water and sediment), and also delineated and modeled the hydrologic and nutrient loads of the watershed for four (4) New Jersey state park lakes: Round Valley swimming area, Lake Absegami, Host Lake, and Hook Creek Lake. This data was then compiled and computed to prepare a Management Plan for each of the individual lakes.
The plans provided specific objectives and recommendations for the short and long-term management of each Lake and its watershed. Both in-lake and watershed management techniques were provided in the plan. In-lake techniques tended to focus on symptomatic problems such as algal blooms and the accumulation of sediments, while watershed techniques tended to focus on reducing pollutant loads through the use of structural and non-structural Best Management Practices (BMPs) and Green Infrastructure (GI) techniques. The management techniques were priority ranked, with these rankings being dependent upon applicability, regulatory constraints, technical feasibility, degree of effectiveness, initial implementation costs, and operations and maintenance costs.
In-lake restoration techniques were designed to improve the water quality and/or aesthetics of the waterbody by alleviating the specific impacts of pollution. Although these measures typically provide only short-term relief without controlling the source of the pollutants, they can substantially improve the aesthetics of a lake while the long-term, watershed-based management practices are being implemented.
In contrast to in-lake restoration techniques, watershed-based techniques focused on the causes of eutrophication rather than the effects. Watershed techniques were not as visible as in-lake techniques and tended to take more time to produce their desired results. However, they were absolutely vital in reducing the pollutant load, as well as producing and sustaining long-term improvements in surface water quality for each of the lakes.
Princeton Hydro was contracted to collaborate with the NY-NJ Harbor and Estuary Program (HEP) and the Town of Kearny to support the enhancement of Kearny Riverbank Park, including areas along the Passaic River shoreline. In addition to addressing the park’s needs, Princeton Hydro had to consider the remedial action work being performed by the U.S. Environmental Protection Agency (EPA) to contain the contaminated sediment within the lower 8.3 miles of the Passaic River and portions of the shoreline at Kearny Riverbank Park.
Through collaborative stakeholder engagement meetings and community input, the site assessment and design provide the Town of Kearny with a multifaceted plan, focusing on shoreline restoration, improving stormwater management, reducing erosion, and improving public access and park amenities.
A key component of the project was to conceptualize stormwater management strategies. Designed to increase infiltration, reduce urban runoff, and improve the water quality of the Passaic River, the stormwater management strategies will help alleviate current stormwater issues such as ponding and erosion. The proposed interventions will provide opportunities for increased park programming, education, and engagement, while improving the park’s climate resilience.
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