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River herring are diadromous fish, which means they migrate between fresh and salt water. On Long Island in Nassau, New York, they migrate between Mill Pond Creek and the ocean, using Bellmore Creek as a highway. The river herring live much of their adult life in the ocean and travel to the freshwaters of Mill Pond Creek in order to spawn.
There is a dam located at the point where Bellmore Creek meets Mill Pond. When the water level isn’t high enough, the river herring can be blocked from swimming upstream to reach their spawning habitat. This not only has negative implications for river herring species, it also negatively impacts the entire ecosystem. The herring are a vital food source for countless other fish, birds and animals, and play a critical role in transferring marine derived nutrients into surrounding estuarine, freshwater and upland habitats.
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.
In 2018, Seatuck Environmental Association, a nonprofit dedicated to wildlife conservation on Long Island, was awarded the NYSDEC Division of Marine Resources Grant for Tributary Restoration and Resiliency to design a fish passage at the dam intersecting Mill Pond and Bellmore Creek. Seatuck contracted Princeton Hydro to design the fish passage options.
The project goals not only include increasing river herring spawning habitat, but also are focused on improving the ecological condition of Bellmore Creek, maintaining and enhancing recreational values, and improving site resiliency to climate change and sea level rise.
To provide guidance on the project, Seatuck 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.
Princeton Hydro conducted a study to understand the feasibility of enhancing fish passage to Mill Pond.
The initial site investigation, in November 2020, included sediment probing and sampling, and a thorough assessment of the existing dam, spillway, water pipes, bridges and upper reaches.
Based on its findings, the Princeton Hydro team developed three design options to restore fish passage:
On June 8 2021, Seatuck, Nassau County and Princeton Hydro held a virtual meeting to get the public’s input on each of the fish passage designs. Emily Hall, Conservation Policy Advocate for Seatuck, also put together an informative presentation in which she provides a synopsis of Bellmore Creek’s history, describes the project goals, and discusses the community engagement process and the results of the public opinion survey. Watch it now:
Additionally, 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. By performing analysis of the longitudinal profile, Princeton Hydro determined that the full dam removal (option 3 listed above) was not recommended due to the potential for initiating uncontrolled channel incision below the original river grade into Mill Pond and upstream reaches.
Ultimately, the technical fish ladder (option 2 listed above) was chosen 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.
The focus on Bellmore Creek is just one of many projects included in Seatuck’s River Revival program, which has sought to clear similarly blocked waterways across Long Island. If you’re interested in learning more about Seatuck’s conservation work and getting involved, click here.
Princeton Hydro has designed, permitted, and overseen solutions for fish passage including the installation of technical and nature-like fishways and the removal of dozens of small and large dams throughout the Northeast. To learn more about our fish passage and dam removal engineering services, click here and check out our blog:
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