Yisroel R.

A major behind-the-scenes upgrade has been completed beneath Prospect Park Lake, giving park officials far greater control over Brooklyn’s only lake while laying the groundwork for a much larger plan to tackle flooding across the surrounding neighborhoods.

The $1.4 million project replaced an aging valve that controls how much water is fed into the lake. With the new system in place, Prospect Park staff can now better regulate lake levels, particularly ahead of heavy rain, when creating extra capacity can help keep stormwater from overwhelming nearby sewers.

The seemingly small upgrade could have a surprisingly large impact. Officials say it is expected to cut the amount of drinking water used for maintenance of the lake from roughly one million gallons a day to about 200,000 gallons, wasting less drinking quality water, while also reducing sewer overflows into Gravesend Bay and the Upper Bay by as much as 12 million gallons each year.

The project is also one of the first pieces of the future Prospect Park Bluebelt, a larger flood-control system planned for the park. That initiative will use natural features including rain gardens and ponds to capture, slow and filter stormwater before it can flood surrounding streets or overload the sewer system.

The work comes as Prospect Park prepares for broader changes around the lake itself. A separate lakeshore restoration project is expected to rebuild portions of the shoreline, improve resilience, add landscaping and wildlife habitat, and create new seating and viewing areas, meaning the latest valve replacement is only an early step in a much larger transformation planned for one of Brooklyn’s best-known green spaces.