Restoration of the Harlem Meer

As part of the overall restoration of the Harlem Meer, the northernmost pond in Central Park, Princeton Hydro was contracted to conduct three specific projects. The first involved the review of a proposed aquascaping plan for the pond. We provided recommendations of the types, arrangement, and densities of plants needed to enhance the pond’s aesthetics while simultaneously minimizing related short and long-term shoreline maintenance needs and costs. Emphasis was placed on the use of attractive, native plants highly tolerant of various hydrologic regimes. Princeton Hydro also supplied recommendations for edge materials along the non-vegetated sections of the pond’s shoreline that would enhance the pond’s aesthetics, create controlled public-access points and alleviate localized erosion problems.

The second task involved the development and implementation of a water quality monitoring program. The program was designed for Central Park Conservancy staff to conduct routine testing and track the status of the pond. Princeton Hydro prepared a sampling protocol, identified the needed sampling equipment, and developed standardized data reporting sheets.

The third task consisted of a baseline assessment of the Meer’s hydrologic budget and pollutant load. Princeton Hydro computed the monthly average inflow to the pond and quantified the Meer’s pollutant load on an annual scale for total phosphorus, total nitrogen, and total suspended solids. These data supported the conclusion that the pond’s algae-related water quality problems would be best controlled by decreasing the amount of available phosphorus. Doing so would decrease the magnitude of algae blooms, decrease the occurrence of blue green algae, and avoid the need for copper sulfate treatments. An experimental alum injection system, consisting of a network of alum diffusers and small aerators, was installed in the pond. The system introduced alum into the pond at set rates on a daily basis or following a storm event. While in operation, the alum system greatly enhanced the pond’s clarity and overall water quality.