The Northampton Local Protection Project is located on the west bank of the Connecticut River in Northampton. The project protects Northampton from Mill River flooding and, in conjunction with upstream reservoirs, from Connecticut River flooding.
Construction began in March 1939 and was completed in June 1941 at a cost of $1.1 million. Grove Street was closed and a portion of Earle Street was relocated. The project is operated and maintained by Northampton.
The project diverts the Mill River through a canal to Ox Bow Lake and is divided into eastern and western sections.
The eastern part of the project protects the city against Connecticut River flooding. It consists of a 5,000 foot long dike with a maximum height of 23 feet that starts from high ground at the intersection of Pomeroy Terrace and Hancock Street. The dike then crosses Meadow Street, Hockanum Road, the Mill River, and U.S. Route 5 before ending about 500 feet west of U.S. Route 5. A pumping station behind the dike near the Mill River removes interior storm water when the river is at high stages. Stoplog structures were constructed where the dike crosses U.S. Route 5 and the Guilford Transportation Company railroad tracks.
The western part of the project protects Northampton against Mill River flooding. An earthfill dike, with a maximum height of 16 feet, begins at high ground near Paradise Pond and extends for 1,100 feet along the east bank of the Mill River to West Street. A 450 foot-long concrete floodwall with a maximum height of 21 feet runs between West Street and the railroad tracks. From the tracks to high ground at Hebert Avenue there is a 900 foot-long earthfill dike with a maximum height of 25 feet. This last section of dike serves as a dam and allows the Mill River to be diverted into a 10,500 foot-long diversion canal, which carries the river to Oxbow Lake.
The project also included construction of a concrete bridge and drop structure where the diversion canal crosses South Street; a smaller concrete bridge at Old Springfield Road near the point where the diversion canal empties into Ox Bow Lake; three stoplog structures; and other drainage features.