2023 Gold Award Recipient 

Silver Lake Drainage Improvements

Nassau County Department of Public Works

Located in Baldwin, NY, the Silver Lake Park and surrounding community were subject to flooding a result of either tidal surges or heavy rainfall events. Localized flooding continued to occur on a frequent basis and the simultaneous combination of tidal surge and rainfall exacerbated the severity of the flooding. This project entailed detailed design of an elevated pond perimeter and walkway, natural shoreline restoration, fish passage and backflow prevention through the installation of a self-regulating tide gate and flap gate.

Originally designed for drainage purposes, the Silver Lake Park is a nine-acre park located within a residential community adjacent to a major county roadway, Merrick Road. Now viewed as a community recreational facility, Silver Lake Park connects three stormwater basins that include Loft’s Pond, Caroline’s Pond and Parsonage’s Creek. With historical and destructive flooding occurring at Silver Lake, flooding mitigation has been long seen as a top priority by Nassau County and the local community.

The primary design goal was to alleviate upland flooding in the community that is also impacted by tidal fluctuations. As a result of the limited space on the downstream side of the western outfall, the design proposed to install the self-regulating tide gate at a point between the culvert’s inlet and outlet located inside the park.  Since fish passage and normal tidal flushing of the lake are desired to be maintained, the design proposed the use of an “ecologically friendly” self‐regulating tide gate (SRT) that stays open during the normal tide cycle and only closes when the tailwater elevation reaches a level that would cause upstream flooding. It was estimated that this elevation would be approximately 3.5’ (NAVD88). This type of tide gate utilizes a system of floats to close the gate at the desired elevation.

The existing channel connecting Caroline’s Lake and Parsonage Creek was preventing the migration of critical species and has been retrofitted to improve fish passage. This was accomplished by altering the geometry of the channel into a trapezoid and installing flexible baffles within the existing culvert.  Shown in the images below, baffles create step pools through a culvert which allows fish or other aquatic organisms to either pass over or around without restricting any water flow.