Reconstruction work on the spillway at Griffith Lake Dam, west of Milford, will begin in August 2026. A contractor will rebuild the concrete spillway and retaining walls and relocate and upgrade the low-level outlet to the south side of the spillway.

The work will correct active seepage and voids under the existing spillway which increase the risk of dam failure. It will be carried out by A-Del Construction. Ramboll Engineering designed the project and will provide construction review during the project.

The Griffith Lake parking lot and boat ramp will be closed during construction. A portion of Griffith Lake Drive will also be closed. Detours will be posted.

The project, funded by DNREC appropriations in the fiscal year 2021, 2022 and 2023 budgets, is expected to be complete in December of 2027.

For more information, please contact Janice Shute, of the DNREC Dam Safety Program, at Janice.Shute@Delaware.gov or 302-739-9146.

About Griffith Lake Dam

Griffith Lake is located in central Delaware, on the west side of the City of Milford. It is formed by an earthen embankment, approximately 860 feet long and 13 feet high, with a 140 foot long concrete spillway with low level outlet wooden stop logs in the center.

The dam is jointly owned by the DNREC Division of Fish and Wildlife and the Delaware Department of Transportation (DelDOT).

The primary use of Griffith Lake is recreation, such as fishing and boating.

The Delaware Environment Observing System (DEOS), at the University of Delaware, provides water level monitoring for many of the publicly owned dams in the state. Data from the Griffiths Lake Dam water level gage can be found on the DEOS Griffiths Lake Dam Station Page.  (A gage height of approximately 0 is normal pond level).

Project Overview

This is a collaborative project, involving the dam owners, DNREC and DelDOT, the DNREC Dam Safety Program, in the Division of Watershed Stewardship. Division of Watershed Stewardship staff will oversee the project.

Background

In 2006, a sinkhole opened up on the right side (looking downstream) of the wingwall, and muddy seepage was observed downstream of the spillway, indicating the loss of bearing material under the spillway. The DNREC 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, indicating the loss of bearing material under the spillway. Temporary solutions were employed, including continuous monitoring and lowering the water level to decrease pressure on the dam.

Attempts to fill the voids were unsuccessful due to multiple seepage entrances, exits and possibly interconnected voids.

The pond level has remained lowered by approximately two feet and clear seepage has continued.                                             

Project Goals

The goal of this project is to improve the safety and sustainability of Griffith’s Lake Dam in Milford. It is critical to complete the reconstruction to protect the safety of the public and to allow the Division of Fish and Wildlife to bring the water level back up to normal levels. 

The installation of a new operable low-level outlet at the side of the spillway will be safer and more efficient for DNREC staff to operate if a storm event or emergency requires the water level to be lowered.

This project will extend the useful life of the dam and reduce the likelihood of more extensive emergency repairs or future costs.