Shirley township, Mount Union borough

Mount Union's Dam On Singers Gap Run

About six miles southwest of Mount Union, on Singers Gap Run, the borough's water supply was held behind a concrete dam built in 1926 and 1927. The report calls it an Ambursen type dam: a reinforced concrete deck resting on buttresses, with expansion joints between them. It had seventeen buttresses on eighteen-foot centers and stood 51 feet above its foundation.

Wooden flashboards along the spillway raised the level of the lake. During Tropical Storm Agnes in June 1972 several of them failed, and between two of the buttresses they were completely removed.

They still had not been repaired on April 16, 1979, when engineers from L. Robert Kimball and Associates of Ebensburg inspected the dam for the Baltimore District of the Corps of Engineers. The inspection came under the National Dam Inspection Act, which authorized the Corps of Engineers to start a program of inspecting dams throughout the United States.

The engineers found the dam itself apparently in good condition. The trouble was the spillway. It could pass only part of the Probable Maximum Flood, and under Corps of Engineers criteria that made it seriously inadequate. Because downstream conditions meant a failure would probably cost lives, the dam was classed as high hazard, and with that spillway the report called it an unsafe, non-emergency dam. It urged a detailed study and changes to increase the spillway's capacity, beginning immediately.

The report noted smaller things too. The bottom intake was silted, and the main drainline had not been opened in 27 years.

Checked and confirmed. Confirmed 2026-10-31 against the sources listed: every factual sentence was tied to a word-for-word passage in its source. Where sources disagreed on a number, the number was left out.

Sources