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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] => 2026-03-06 13:31:30 [post_modified_gmt] => 2026-03-06 13:31:30 [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 ) [1] => WP_Post Object ( [ID] => 19281 [post_author] => 1 [post_date] => 2026-03-05 19:57:58 [post_date_gmt] => 2026-03-05 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] => 2026-03-05 20:21:18 [post_modified_gmt] => 2026-03-05 20:21:18 [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 ) [2] => WP_Post Object ( [ID] => 19061 [post_author] => 1 [post_date] => 2026-01-12 21:50:23 [post_date_gmt] => 2026-01-12 21:50:23 [post_content] => 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. [gallery link="none" size="medium" ids="19062,19063,19064"] 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. [post_title] => New Jersey State Park - Diagnostic Feasibility Lake Studies [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => new-jersey-state-park-diagnostic-feasibility-lake-studies [to_ping] => [pinged] => [post_modified] => 2026-01-12 21:52:34 [post_modified_gmt] => 2026-01-12 21:52:34 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=19061 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [3] => WP_Post Object ( [ID] => 18823 [post_author] => 1 [post_date] => 2025-09-08 21:39:16 [post_date_gmt] => 2025-09-08 21:39:16 [post_content] => The Ousatonic Fish and Game Protective Association, Inc., in partnership with the Connecticut Department of Energy and Environmental Protection’s Inland Fisheries Division, sought to remove the Papermill Pond Dam on the East Aspetuck River to restore fish habitat formerly exceptional in quality for trout, facilitate fish passage through the site, and improve accessibility and functionality for people to engage in outdoor activities at the site in order to foster deeper stewardship ethic for the watershed. The Papermill Pond Dam, located in New Milford, is an embankment dam situated on the East Aspetuck River. It is located 2.9 miles upstream of the confluence with the Housatonic River and is the first barrier on the East Aspetuck River. The spillway is concrete capped with masonry core. It has an approximate structural height of 11 feet and length of 75 feet. The following alternatives were analyzed: 1) no action; 2) fishway bypass channel around dam; 3) technical fishway at dam; 4) dam lowering with fishway at dam; 5) river bypass and off-line pond; and, 6) full removal. Conceptual designs were developed for each alternative. Each alternative was analyzed and rated numerically relative to twelve categories: river morphology, aquatic resources (fisheries, macroinvertebrates, water quality), recreation, historic resources, flooding, relative liability, relative short-term costs, relative long-term costs, availability of funds, and anticipated permitability. Dam removal ranked as the most feasible alternative, but dam repair stood out as the best option for maintaining the existing ease of recreational access. That alternative necessitated dam repair, ongoing maintenance and inspection, both short-term and long-term sediment dredging, and construction of a fish bypass channel. The Association considered the alternatives and decided to pursue full dam removal. Based on negotiations with CTDEEP that considered impacts to downstream habitats and other applicable regulations, the resulting recommendation was to remove a portion of the impounded sediment prior to passive release of the remaining impounded sediment, regardless of potential contamination. This minimized transitory sediment deposition in downstream habitats, thereby reducing the short-term impacts of the project. Thus, sediment proximal to the dam is proposed to be excavated and permanently deposited in upland areas onsite. The dam was successfully removed in 2019 under supervision of CTDEEP Fisheries Division and Princeton Hydro. [post_title] => Papermill Pond Dam Removal and River Restoration Project [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => papermill-pond-dam-removal-and-river-restoration-project [to_ping] => [pinged] => [post_modified] => 2025-12-08 21:44:09 [post_modified_gmt] => 2025-12-08 21:44:09 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=18823 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [4] => WP_Post Object ( [ID] => 15745 [post_author] => 1 [post_date] => 2024-09-18 10:08:48 [post_date_gmt] => 2024-09-18 10:08:48 [post_content] => Princeton Hydro was on the team to study the Bronx River Double Dam for New York City Parks (the dam owner). The project goal was to present an economically, environmentally, and socially sustainable long-term fish-passage solution for the Bronx River Double Dam. [gallery link="none" size="medium" ids="15744,15743,15742"] The culmination of the project was a fish passage Alternatives Analysis for the dam site, where the cost and benefits of various long-term solutions for the project site were assessed, including dam removal and an engineered fishway. To inform the Alternatives Analysis, Princeton Hydro first studied the feasibility of the removal of the Bronx River Double Dam. To inform the dam removal feasibility study and a conceptual dam removal design, Princeton Hydro supplemented data from a previous technical fishway design with data collected from additional field investigations. Princeton Hydro led the field collection effort, including sediment sampling, sediment probing, and a bathymetric survey to shed light on the impounded sediment concerns. Field investigations also included an investigation on the infrastructure, an updated topographic survey, and a seismic refraction survey to understand the potential for underlying bedrock to inform a conceptual design for dam removal. Based on the data reviewed, Princeton Hydro concluded that dam removal is feasible and that its removal would 1) Restore the Bronx River to its historical flowpath, 2) Likely restore transparent fish passage at the site, and 3) Not impact infrastructure. In comparing the dam removal alternative to the engineering fishway, the dam removal would provide a greater ecological benefit, while also reducing long term liabilities related to dam failure and costs associated with dam maintenance and inspection. Despite uncertainty associated with the dam removal alternative at this stage in the concept design, it is expected the upfront construction cost of the dam removal would be higher than the engineering fishway alternative. The feasibility study and alternatives analysis set the stage for the US Army Corps of Engineers to further study fish passage at the Bronx River Double Dam. [post_title] => Bronx River Double Dam Fish Passage Assessment [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => bronx-river-double-dam-fish-passage-assessment [to_ping] => [pinged] => [post_modified] => 2024-09-18 10:09:22 [post_modified_gmt] => 2024-09-18 10:09:22 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=15745 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [5] => WP_Post Object ( [ID] => 14093 [post_author] => 1 [post_date] => 2023-12-13 11:31:44 [post_date_gmt] => 2023-12-13 11:31:44 [post_content] => The Collins Company Lower Dam, constructed in 1910 as a hydroelectric dam, is located on the Farmington River, approximately 1 mile downstream (south) of the Collinsville Dam and State Route 179, in Avon, Connecticut, south of the Collinsville Town border and across the Farmington River from the Town of Burlington. In 2011, a pre-feasibility study was completed on the Collinsville Dam and the Collins Company Lower Dam to determine whether these defunct hydroelectric dams could be repowered. The study found that repowering only one of the dams was economically feasible. [caption id="attachment_13849" align="aligncenter" width="718"] Collins Company Lower Dam prior to removal. Photo by CT Insider.[/caption] In 2019, Canton Hydro, LLC began the retrofit of the Collinsville Dam for hydroelectric generation in conjunction with the construction of a fishway in order to allow passage of anadromous fish (i.e., American Shad, Alewife, Blueback Herring, and Sea Lamprey) to the upstream reaches of the Farmington River. Removal of the Collins Company Lower Dam will allow passage to the base of the newly retrofitted Collinsville Dam. The goals of this project are to eliminate a barrier to migratory fish; eliminate an obsolete dam; remove a public safety risk; re-create a free flowing, ecologically productive, and natural river channel; and create stable and safe public access. Also as noted above, this dam removal is imperative to enable fish passage at the fishway under construction at the Collinsville Dam, approximately one mile upstream. As part of the dam removal design process, Princeton Hydro developed a Sediment Management Plan, which involved assessing impounded sediment quality and quantity by conducting bathymetric mapping to sense elevation of top and bottom of unconsolidated sediment, and sampling and analyzing sediment for a broad range of contaminants. In addition to using the information gathered through the assessment, a professional survey and geomorphic concepts were used to determine the volume of impounded sediment and the anticipated river profile following dam removal. Princeton Hydro completed the bathymetric surveys, hydrologic and hydraulic analysis, geotechnical engineering, construction phasing determination, demolition and blasting plans, preparation of 30%, 60%, 90% and 100% designs, and regulatory review applications. Princeton Hydro is currently working through the engineering designs and permit applications. [post_title] => Collins Company Lower Dam Removal [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => collins-company-lower-dam-removal [to_ping] => [pinged] => [post_modified] => 2023-12-13 11:31:44 [post_modified_gmt] => 2023-12-13 11:31:44 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=14093 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [6] => WP_Post Object ( [ID] => 13647 [post_author] => 1 [post_date] => 2023-08-16 11:24:12 [post_date_gmt] => 2023-08-16 11:24:12 [post_content] => Under a multi-year renewal contract with the New Jersey Division of Property Management, Princeton Hydro provided sediment, quantification, sampling and analysis services for the Warren Mill Dam impoundment. The project was initiated to understand the amount of sediment behind the dam that would require management or release to create a stable fluvial river channel pending dam removal; understand the geotechnical qualities of the sediment, and; determine the contaminant (HTRW) concentrations within the sediment in relation to ecological screening and human health criteria. [gallery columns="2" link="none" ids="13651,13650"] The initial fieldwork encompassed a bathymetric/hydrographic survey utilizing a combination of a Knudsen dual frequency sounder and survey measurements, both tied to a real time kinematic (RTK) survey grade global positioning system (GPS). Following the completion of the field survey, the top of sediment topography was generated and used to develop initial volume estimates. Utilizing this data, a sediment sampling and analysis plan (SSAP) was developed with NJDEP, and NJDEP Land Use Permits and landowner permissions were acquired (right of entry). Once the SSAP was approved, the environmental/geotechnical borings were conducted. A total of 15 borings were completed from a bargemounted tripod SPT rig by Princeton Hydro and Unitech Drilling. All borings were progressed to refusal on bedrock, and the stratigraphy and lithology of the sediment and soils were logged, including standard penetration tests. Additionally, samples were collected for chemical analysis, including river water samples, to complete elutriate testing to assess the mobility of contaminants during the dam removal process. [gallery columns="2" link="none" ids="13652,13649"] Princeton Hydro collected split samples for both HTRW analysis performed by an independent analytical laboratory, and grain size analysis, moisture content, organic content, and Atterberg limits performed by Princeton Hydro’s in-house AASHTO-accredited and USACE-certified geotechnical laboratory. Field logs were finalized, and a report was prepared describing the field operations, observations, conclusions and recommendations. The report also included a hydrographic map of the impoundment, boring locations, boring logs, analytical results, an interpretive fence diagram of the sediment stratigraphy between borings, and volume calculations. [post_title] => Warren Mill Dam Sediment Investigation [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => warren-mill-dam-sediment-investigation [to_ping] => [pinged] => [post_modified] => 2024-10-03 12:24:54 [post_modified_gmt] => 2024-10-03 12:24:54 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=13647 [menu_order] => 1 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [7] => WP_Post Object ( [ID] => 12985 [post_author] => 1 [post_date] => 2023-07-12 13:59:41 [post_date_gmt] => 2023-07-12 13:59:41 [post_content] => Greenwood Lake is located on the border of Orange County, New York and Passaic County, New Jersey, and is a highly valued recreational, ecological, and potable water resource. It is one of the headwater systems that feeds the Wanaque Reservoir, which provides drinking water to over 2.3 million people. Greenwood Lake is on both States’ 303(d) list for being impaired by phosphorus. A phosphorus Total Maximum Daily Load (TMDL) was completed and proposed by NJDEP in June 2004 and established in September 2004. The NYSDEC reviewed the TMDL and formally agreed with the existing and targeted loads in 2005. Princeton Hydro staff have been working on Greenwood Lake since the early 1980s when the Phase I Diagnostic and Feasibility study was completed. Princeton Hydro completed a prioritized Stormwater Implementation Plan, approved by NJDEP in 2006, which identified a series of stormwater projects to comply with the NJ contribution to the phosphorus TMDL. A similar Stormwater Implementation Plan was developed for the New York end of the watershed in 2008. [gallery link="none" ids="3854,12978,12977"] As part of a 319(h) grant, Princeton Hydro conducted engineering analyses and design work for the installation of six stormwater Best Management Practices (BMP) to reduce the Total Phosphorus (TP) and Total Suspended Solid (TSS) loads entering Greenwood Lake and comply with the TMDL. These BMPs include the installation of two vegetated bioretention swales; a baffle box and polisher Manufactured Treatment Device (MTD) unit by Suntree Technologies Inc; two Bay separator MTD devices by Baysaver Technologies, Inc; and a VORTECHS model 3000 MTD by Vortechnics, Inc. Princeton Hydro oversaw the installation of the structures and monitored stormwater upgradient and downgradient of the installed BMPs to measure their efficacy in TP and TSS reductions. Princeton Hydro has conducted extensive in-lake, stream, and stormwater monitoring in accordance with the Quality Assurance Project Plans approved by NJDEP. Sampling included measurements of flow at eight tributary sites (six in the New Jersey end and two in the New York end), the collection of water samples for analysis, and collecting in-situ data (dissolved oxygen, temperature, pH, and conductivity). As part of a NJ Highlands Council grant, Princeton Hydro updated Greenwood Lake’s Restoration Plan for the NJ end of the lake to a 9-Element Watershed Implementation Plan (WIP) to further identify NPS reduction. The updated WIP was completed in early 2020. Princeton Hydro recently modeled flow discharge and pollutant load from Belcher Creek, Greenwood Lake’s main input and source of nutrient loading, in order to evaluate the feasibility of a ferric sulfate infusion system to address phosphorus inputs. Such a system would decrease the amount of phosphorus being introduced into the lake and prevent HABs from occurring. This project was funded by NJDEP Harmful Algal Bloom (HAB) grants and was completed in 2021. [post_title] => Greenwood Lake Watershed Implementation Plan [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => greenwood-lake-watershed-implementation-plan [to_ping] => [pinged] => [post_modified] => 2023-07-13 14:00:27 [post_modified_gmt] => 2023-07-13 14:00:27 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=12985 [menu_order] => 15 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [8] => WP_Post Object ( [ID] => 11877 [post_author] => 1 [post_date] => 2022-11-16 15:40:44 [post_date_gmt] => 2022-11-16 15:40:44 [post_content] => The Finesville Dam served as the first full barrier on the Musconetcong River, a major tributary of the Delaware River, which is the largest undammed river on the east coast. With a committed coalition of stakeholders led by the Musconetcong Watershed Association, Princeton Hydro was contracted to complete a feasibility study and, in later phases, final engineering designs, permitting, and construction guidance. Funding support was provided by the NOAA–American Rivers partnership and US Department of Agriculture’s Natural Resources Conservation Service. Finesville Dam was first built for an iron forge around 1751 and was later used to power a gristmill on the opposite side of the river. In the early 1900s, the dam was reconstructed with concrete. Given the area’s historic context, an archaeological survey was completed during the planning stages. Princeton Hydro completed a full bathymetric survey of the impoundment, calculated the volume of sediment, and analyzed samples for geotechnical and chemical qualities. Hydrologic and hydraulic analyses were completed to determine if downstream properties would be impacted by increased flow. Princeton Hydro was then hired to develop a dam removal design to incorporate historic preservation objectives and adjacent landowner interests by retaining the abutments as a physical remnant of the dam on the site. In addition, a boulder weir was designed to maintain a falling water aesthetic spanning the channel and yet allows for free movement of fish. [gallery columns="2" link="none" ids="11875,11876"] With much fanfare and public attention, the historic dam was removed in November 2011, restoring fish passage from the Atlantic for the first time in almost 300 years. During construction, a professional archaeologist was onsite to document structural elements. Princeton Hydro coordinated with the contractor and local residents to set aside dam timbers and other features for long-term display. Princeton Hydro and the contractor worked with adjacent residents to provide additional bank terracing and stabilization with soil lifts and live stake plantings to allow for continued public access. As a result of this successful removal, three miles of the Musconetcong River have been opened and attention has turned to upstream barriers. [post_title] => Finesville Dam Study and Removal [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => finesville-dam-study-and-removal [to_ping] => [pinged] => [post_modified] => 2022-11-16 15:40:44 [post_modified_gmt] => 2022-11-16 15:40:44 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=11877 [menu_order] => 32 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [9] => WP_Post Object ( [ID] => 10415 [post_author] => 1 [post_date] => 2022-03-08 14:27:40 [post_date_gmt] => 2022-03-08 14:27:40 [post_content] => Seatuck Environmental Association contracted Princeton Hydro to assess fish passage options for the dam at Mill Pond on Bellmore Creek. Project goals include increasing River Herring spawning habitat, improving the ecological condition of Bellmore Creek, maintaining and enhancing recreational values, improving site resiliency to climate change and sea level rise. River Herring have been documented at the base of the dam at Mill Pond for the past several migration seasons. Bellmore Creek is one of only two-dozen streams on Long Island where remnant runs of this ecologically valuable, diadromous fish still exist. To provide guidance on the project, Seatuck Environmental Association assembled an advisory committee with representation from Nassau County (dam owner), New York State Office of Parks, NYS Department of Environmental Conservation, Nassau County Soil and Water District, Town of Hempstead, the South Shore Estuary Reserve, Trout Unlimited, The Nature Conservancy, South Shore Audubon, and the Bellmore Civic Association. Our project team conducted a fish passage feasibility study and outlined three options to restore fish passage a virtual meeting to the advisory team:
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.
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.
The Ousatonic Fish and Game Protective Association, Inc., in partnership with the Connecticut Department of Energy and Environmental Protection’s Inland Fisheries Division, sought to remove the Papermill Pond Dam on the East Aspetuck River to restore fish habitat formerly exceptional in quality for trout, facilitate fish passage through the site, and improve accessibility and functionality for people to engage in outdoor activities at the site in order to foster deeper stewardship ethic for the watershed.
The Papermill Pond Dam, located in New Milford, is an embankment dam situated on the East Aspetuck River. It is located 2.9 miles upstream of the confluence with the Housatonic River and is the first barrier on the East Aspetuck River. The spillway is concrete capped with masonry core. It has an approximate structural height of 11 feet and length of 75 feet.
The following alternatives were analyzed: 1) no action; 2) fishway bypass channel around dam; 3) technical fishway at dam; 4) dam lowering with fishway at dam; 5) river bypass and off-line pond; and, 6) full removal. Conceptual designs were developed for each alternative. Each alternative was analyzed and rated numerically relative to twelve categories: river morphology, aquatic resources (fisheries, macroinvertebrates, water quality), recreation, historic resources, flooding, relative liability, relative short-term costs, relative long-term costs, availability of funds, and anticipated permitability. Dam removal ranked as the most feasible alternative, but dam repair stood out as the best option for maintaining the existing ease of recreational access. That alternative necessitated dam repair, ongoing maintenance and inspection, both short-term and long-term sediment dredging, and construction of a fish bypass channel. The Association considered the alternatives and decided to pursue full dam removal.
Based on negotiations with CTDEEP that considered impacts to downstream habitats and other applicable regulations, the resulting recommendation was to remove a portion of the impounded sediment prior to passive release of the remaining impounded sediment, regardless of potential contamination. This minimized transitory sediment deposition in downstream habitats, thereby reducing the short-term impacts of the project. Thus, sediment proximal to the dam is proposed to be excavated and permanently deposited in upland areas onsite.
The dam was successfully removed in 2019 under supervision of CTDEEP Fisheries Division and Princeton Hydro.
Princeton Hydro was on the team to study the Bronx River Double Dam for New York City Parks (the dam owner). The project goal was to present an economically, environmentally, and socially sustainable long-term fish-passage solution for the Bronx River Double Dam.
The culmination of the project was a fish passage Alternatives Analysis for the dam site, where the cost and benefits of various long-term solutions for the project site were assessed, including dam removal and an engineered fishway. To inform the Alternatives Analysis, Princeton Hydro first studied the feasibility of the removal of the Bronx River Double Dam.
To inform the dam removal feasibility study and a conceptual dam removal design, Princeton Hydro supplemented data from a previous technical fishway design with data collected from additional field investigations. Princeton Hydro led the field collection effort, including sediment sampling, sediment probing, and a bathymetric survey to shed light on the impounded sediment concerns. Field investigations also included an investigation on the infrastructure, an updated topographic survey, and a seismic refraction survey to understand the potential for underlying bedrock to inform a conceptual design for dam removal.
Based on the data reviewed, Princeton Hydro concluded that dam removal is feasible and that its removal would 1) Restore the Bronx River to its historical flowpath, 2) Likely restore transparent fish passage at the site, and 3) Not impact infrastructure.
In comparing the dam removal alternative to the engineering fishway, the dam removal would provide a greater ecological benefit, while also reducing long term liabilities related to dam failure and costs associated with dam maintenance and inspection. Despite uncertainty associated with the dam removal alternative at this stage in the concept design, it is expected the upfront construction cost of the dam removal would be higher than the engineering fishway alternative.
The feasibility study and alternatives analysis set the stage for the US Army Corps of Engineers to further study fish passage at the Bronx River Double Dam.
The Collins Company Lower Dam, constructed in 1910 as a hydroelectric dam, is located on the Farmington River, approximately 1 mile downstream (south) of the Collinsville Dam and State Route 179, in Avon, Connecticut, south of the Collinsville Town border and across the Farmington River from the Town of Burlington. In 2011, a pre-feasibility study was completed on the Collinsville Dam and the Collins Company Lower Dam to determine whether these defunct hydroelectric dams could be repowered. The study found that repowering only one of the dams was economically feasible.
In 2019, Canton Hydro, LLC began the retrofit of the Collinsville Dam for hydroelectric generation in conjunction with the construction of a fishway in order to allow passage of anadromous fish (i.e., American Shad, Alewife, Blueback Herring, and Sea Lamprey) to the upstream reaches of the Farmington River. Removal of the Collins Company Lower Dam will allow passage to the base of the newly retrofitted Collinsville Dam.
The goals of this project are to eliminate a barrier to migratory fish; eliminate an obsolete dam; remove a public safety risk; re-create a free flowing, ecologically productive, and natural river channel; and create stable and safe public access. Also as noted above, this dam removal is imperative to enable fish passage at the fishway under construction at the Collinsville Dam, approximately one mile upstream.
As part of the dam removal design process, Princeton Hydro developed a Sediment Management Plan, which involved assessing impounded sediment quality and quantity by conducting bathymetric mapping to sense elevation of top and bottom of unconsolidated sediment, and sampling and analyzing sediment for a broad range of contaminants. In addition to using the information gathered through the assessment, a professional survey and geomorphic concepts were used to determine the volume of impounded sediment and the anticipated river profile following dam removal.
Princeton Hydro completed the bathymetric surveys, hydrologic and hydraulic analysis, geotechnical engineering, construction phasing determination, demolition and blasting plans, preparation of 30%, 60%, 90% and 100% designs, and regulatory review applications.
Princeton Hydro is currently working through the engineering designs and permit applications.
Under a multi-year renewal contract with the New Jersey Division of Property Management, Princeton Hydro provided sediment, quantification, sampling and analysis services for the Warren Mill Dam impoundment. The project was initiated to understand the amount of sediment behind the dam that would require management or release to create a stable fluvial river channel pending dam removal; understand the geotechnical qualities of the sediment, and; determine the contaminant (HTRW) concentrations within the sediment in relation to ecological screening and human health criteria.
The initial fieldwork encompassed a bathymetric/hydrographic survey utilizing a combination of a Knudsen dual frequency sounder and survey measurements, both tied to a real time kinematic (RTK) survey grade global positioning system (GPS). Following the completion of the field survey, the top of sediment topography was generated and used to develop initial volume estimates. Utilizing this data, a sediment sampling and analysis plan (SSAP) was developed with NJDEP, and NJDEP Land Use Permits and landowner permissions were acquired (right of entry). Once the SSAP was approved, the environmental/geotechnical borings were conducted.
A total of 15 borings were completed from a bargemounted tripod SPT rig by Princeton Hydro and Unitech Drilling. All borings were progressed to refusal on bedrock, and the stratigraphy and lithology of the sediment and soils were logged, including standard penetration tests. Additionally, samples were collected for chemical analysis, including river water samples, to complete elutriate testing to assess the mobility of contaminants during the dam removal process.
Princeton Hydro collected split samples for both HTRW analysis performed by an independent analytical laboratory, and grain size analysis, moisture content, organic content, and Atterberg limits performed by Princeton Hydro’s in-house AASHTO-accredited and USACE-certified geotechnical laboratory. Field logs were finalized, and a report was prepared describing the field operations, observations, conclusions and recommendations. The report also included a hydrographic map of the impoundment, boring locations, boring logs, analytical results, an interpretive fence diagram of the sediment stratigraphy between borings, and volume calculations.
Greenwood Lake is located on the border of Orange County, New York and Passaic County, New Jersey, and is a highly valued recreational, ecological, and potable water resource. It is one of the headwater systems that feeds the Wanaque Reservoir, which provides drinking water to over 2.3 million people. Greenwood Lake is on both States’ 303(d) list for being impaired by phosphorus. A phosphorus Total Maximum Daily Load (TMDL) was completed and proposed by NJDEP in June 2004 and established in September 2004. The NYSDEC reviewed the TMDL and formally agreed with the existing and targeted loads in 2005.
Princeton Hydro staff have been working on Greenwood Lake since the early 1980s when the Phase I Diagnostic and Feasibility study was completed. Princeton Hydro completed a prioritized Stormwater Implementation Plan, approved by NJDEP in 2006, which identified a series of stormwater projects to comply with the NJ contribution to the phosphorus TMDL. A similar Stormwater Implementation Plan was developed for the New York end of the watershed in 2008.
As part of a 319(h) grant, Princeton Hydro conducted engineering analyses and design work for the installation of six stormwater Best Management Practices (BMP) to reduce the Total Phosphorus (TP) and Total Suspended Solid (TSS) loads entering Greenwood Lake and comply with the TMDL. These BMPs include the installation of two vegetated bioretention swales; a baffle box and polisher Manufactured Treatment Device (MTD) unit by Suntree Technologies Inc; two Bay separator MTD devices by Baysaver Technologies, Inc; and a VORTECHS model 3000 MTD by Vortechnics, Inc. Princeton Hydro oversaw the installation of the structures and monitored stormwater upgradient and downgradient of the installed BMPs to measure their efficacy in TP and TSS reductions.
Princeton Hydro has conducted extensive in-lake, stream, and stormwater monitoring in accordance with the Quality Assurance Project Plans approved by NJDEP. Sampling included measurements of flow at eight tributary sites (six in the New Jersey end and two in the New York end), the collection of water samples for analysis, and collecting in-situ data (dissolved oxygen, temperature, pH, and conductivity).
As part of a NJ Highlands Council grant, Princeton Hydro updated Greenwood Lake’s Restoration Plan for the NJ end of the lake to a 9-Element Watershed Implementation Plan (WIP) to further identify NPS reduction. The updated WIP was completed in early 2020. Princeton Hydro recently modeled flow discharge and pollutant load from Belcher Creek, Greenwood Lake’s main input and source of nutrient loading, in order to evaluate the feasibility of a ferric sulfate infusion system to address phosphorus inputs. Such a system would decrease the amount of phosphorus being introduced into the lake and prevent HABs from occurring. This project was funded by NJDEP Harmful Algal Bloom (HAB) grants and was completed in 2021.
The Finesville Dam served as the first full barrier on the Musconetcong River, a major tributary of the Delaware River, which is the largest undammed river on the east coast. With a committed coalition of stakeholders led by the Musconetcong Watershed Association, Princeton Hydro was contracted to complete a feasibility study and, in later phases, final engineering designs, permitting, and construction guidance. Funding support was provided by the NOAA–American Rivers partnership and US Department of Agriculture’s Natural Resources Conservation Service.
Finesville Dam was first built for an iron forge around 1751 and was later used to power a gristmill on the opposite side of the river. In the early 1900s, the dam was reconstructed with concrete. Given the area’s historic context, an archaeological survey was completed during the planning stages.
Princeton Hydro completed a full bathymetric survey of the impoundment, calculated the volume of sediment, and analyzed samples for geotechnical and chemical qualities. Hydrologic and hydraulic analyses were completed to determine if downstream properties would be impacted by increased flow. Princeton Hydro was then hired to develop a dam removal design to incorporate historic preservation objectives and adjacent landowner interests by retaining the abutments as a physical remnant of the dam on the site. In addition, a boulder weir was designed to maintain a falling water aesthetic spanning the channel and yet allows for free movement of fish.
With much fanfare and public attention, the historic dam was removed in November 2011, restoring fish passage from the Atlantic for the first time in almost 300 years. During construction, a professional archaeologist was onsite to document structural elements. Princeton Hydro coordinated with the contractor and local residents to set aside dam timbers and other features for long-term display.
Princeton Hydro and the contractor worked with adjacent residents to provide additional bank terracing and stabilization with soil lifts and live stake plantings to allow for continued public access. As a result of this successful removal, three miles of the Musconetcong River have been opened and attention has turned to upstream barriers.
Seatuck Environmental Association contracted Princeton Hydro to assess fish passage options for the dam at Mill Pond on Bellmore Creek. Project goals include increasing River Herring spawning habitat, improving the ecological condition of Bellmore Creek, maintaining and enhancing recreational values, improving site resiliency to climate change and sea level rise. River Herring have been documented at the base of the dam at Mill Pond for the past several migration seasons. Bellmore Creek is one of only two-dozen streams on Long Island where remnant runs of this ecologically valuable, diadromous fish still exist.
To provide guidance on the project, Seatuck Environmental Association assembled an advisory committee with representation from Nassau County (dam owner), New York State Office of Parks, NYS Department of Environmental Conservation, Nassau County Soil and Water District, Town of Hempstead, the South Shore Estuary Reserve, Trout Unlimited, The Nature Conservancy, South Shore Audubon, and the Bellmore Civic Association. Our project team conducted a fish passage feasibility study and outlined three options to restore fish passage a virtual meeting to the advisory team:
Princeton Hydro completed a site investigation including topographic survey, sediment probing and sampling, and assessment of structures to identify project opportunities and site constraints. Sediment sampling and analysis indicated no major concerns with contamination. Through analysis of the longitudinal profile, Princeton Hydro determined that full dam removal was not recommended due to the potential for initiating uncontrolled channel incision below original river grade into Mill Pond and upstream reaches. As the dam owner, Nassau County ultimately selected the Technical Fish Ladder as the most appropriate solution for restoring fish passage to Mill Pond and maintaining existing recreational values. Princeton Hydro is currently developing preliminary engineering design plans for this selected alternative as part of this phase of the project.
This project was funded via a NYSDEC Division of Marine Resources Grant for Tributary Restoration and Resiliency awarded to Seatuck Environmental Association in 2018.
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