MILFORD, Del. - Reconstruction work on the spillway at Griffith Lake Dam, west of Milford, will begin in August 2026, according to the Delaware Department of Natural Resources and Environmental Control. A-Del Construction will rebuild the concrete spillway and retaining walls and relocate and upgrade the low-level outlet to the south side of the spillway.
DNREC says the work will correct active seepage and voids beneath the existing spillway that increase the risk of dam failure. The Griffith Lake parking lot and boat ramp will be closed during construction. A portion of Griffith Lake Drive will also be closed, with detours posted.
The project is funded through DNREC appropriations in the fiscal 2021, 2022 and 2023 budgets and is expected to be completed in December 2027. Griffith Lake Dam consists of an earthen embankment approximately 860 feet long and 13 feet high, with a 140-foot-long concrete spillway. The dam is jointly owned by the DNREC Division of Fish and Wildlife and the Delaware Department of Transportation.
Griffith Lake is primarily used for recreation, including fishing and boating.
According to DNREC, a sinkhole opened on the right side of the spillway wingwall in 2006, and muddy seepage was observed downstream, indicating the loss of bearing material beneath the spillway. The Division of Fish and Wildlife made emergency repairs and constructed two concrete blocks on the upstream side of the spillway to prevent seepage.
In 2023, muddy seepage carrying sediment was observed downstream of the low-level outlet, again indicating the loss of bearing material beneath the spillway. Temporary measures included continuous monitoring and lowering the water level to decrease pressure on the dam.
DNREC says attempts to fill the voids were unsuccessful because of multiple seepage entrances and exits and possibly interconnected voids. The pond level has remained about 2 feet below normal, and clear seepage has continued. The goal of the project is to improve the safety and sustainability of Griffith Lake Dam, protect public safety and allow the Division of Fish and Wildlife to return the lake to its normal water level.
DNREC says the new operable low-level outlet will also be safer and more efficient for staff to use if the water level needs to be lowered during a storm or emergency. The department says the project will extend the useful life of the dam and reduce the likelihood of more extensive emergency repairs or future costs.
