The Rehabilitation of Clyde Potts Reservoir Dam, Morris County, New Jersey

Clyde Potts Reservoir and Dam are located in the Township of Mendham, Morris County, New Jersey approximately five miles west of Morristown. The reservoir and dam, which are owned and operated by the Southeast Morris County Municipal Utilities Authority (SMCMUA), impound water used as part of the municipal water supply for the SMCMUA service area. The 1460 foot long, 60 foot high earthfill dam was built across Harmony Brook between 1929 and 1932 and impounds a reservoir of approximately 44 acres. As part of the National Dam Safety Program, a Phase I Inspection Report (Ref. 5) was completed for the Clyde Potts Reservoir Dam in 1979. The report recommended upgrading the dam to assure its continued integrity. The most serious deficiency noted was the inability of the existing spillway to pass the Probable Maximum Flood (PMF). The Phase I Inspection Report classified the dam as having “High Hazard Potential” based on the downstream property damage that could occur in the event of a complete failure of the dam. Based on this classification, modifications to the existing spillway were required by the State of New Jersey (Ref. 4) to pass the PMF. SMCMUA implemented the majority of the recommendations presented in the Phase I Inspection Report and has evaluated alternative means of reconstructing the dam spillway to adequately pass the PMF.