The Worcester Local Protection Project, also referred to as the Worcester Diversion Project, is located in the towns of Auburn and Millbury. The project significantly reduces the threat of flooding in Worcester, where heavy flood losses have occurred to industrial, commercial, residential, and public property. Construction started in July 1957 and was completed in January 1960 at a cost of $5.2 million. Worcester operates and maintains the project.
The project allows potential floodwaters originating in the Leesville Pond area to bypass Worcester by conveying them through a diversion tunnel to the Blackstone River. These floodwaters would normally flow through seven miles of river channel adjacent to a heavily developed area of Worcester.
The project features a gated concrete control dam built across Kettle Brook. The dam is 180 feet long with a crest elevation of 492 feet. The control dam is located about 1.25 miles upstream of Leesville Pond Dam. There is a 350-foot-long earthfill dike with stone slope protection that has a maximum elevation of 498 feet. Immediately upstream of the control dam, an ungated semicircular weir forms the entrance to the circular diversion tunnel and is 143 feet long with a maximum elevation of 487 feet. The circular diversion tunnel, measuring 4,205 feet long and 16 feet in diameter, runs under Pakachoag Hill to an open channel. The first 440 feet is built in earth, and the remainder is cut through rock. The entire length of the tunnel is lined in concrete.
Beyond, an 11,300-foot-long open channel, consisting of both earth and rock, follows the general alignment of Hull Brook and empties into the Blackstone River. Four highway bridges and a railroad bridge were built across the open channel. The highway bridges are located at U.S. Route 20, Pinrock Road, the Massachusetts Turnpike, and Greenwood Street. The railroad bridge is located near the channel's junction with the Blackstone River.