The Mill Creek Flood Control Project consists of the Diversion Dam, intake canal, Bennington Lake, Mill Creek Storage Dam, Russell Creek canal, Mill Creek return canal, and the Mill Creek Channel. Construction of the dam and its associated works was completed in 1942.
When flows through Mill Creek rise too high, the Diversion Dam diverts the excess, via the intake canal, into Bennington Lake, which is impounded by Mill Creek Storage Dam. Mill Creek Storage Dam is an earth-fill structure with a heavy gravel face. It is 800 feet wide at the base, 125 feet high and 3,200 feet long at the crest. After a high-water event, water in Bennington Lake is released via the Russell Creek canal and the Mill Creek return canal. Water that is not diverted into the lake travels down the Mill Creek Channel, through the middle of the city.
History
On March 31, 1931, an estimated 6.65 inches of intense rainfall created what was termed “the worst flood in Walla Walla’s history.” The floodwaters resulted in extensive damages throughout the city. This flood, and concerns over the reoccurring nature of Mill Creek’s floods, prompted Virgil B. Bennington, then President of the Walla Walla Chamber of Commerce, to lobby the U.S. Congress for flood protection. The project was authorized by the Flood Control Act of 1938.
Bennington Lake
This off-stream reservoir has a maximum storage capacity of 8,300 acre-feet for flood control. It also provides a variety recreation opportunities, including hiking, fishing, hunting, boating and picnicking.
In the spring, water is diverted from Mill Creek to Bennington Lake once the risk of flooding is over. The lake is stocked with rainbow trout by the Washington Department of Fish and Wildlife.
Boating on the lake is limited to paddling, rowing, wind power, or vessels with electric motors. No gas engines are allowed on the water at any time. This policy protects the lake from unwanted pollutants associated with gasoline-operated motors and provides maximum space for vessels compatible with the lake’s small size.
Picnic tables, shelters and restrooms are available at the lake parking lot. There is also a life jacket loaner board to help keep everyone safe on the water.
Hunting is permitted around Bennington Lake, subject to Washington State regulations, in the areas designated on the map.
The Bennington Lake area is open year-round 5 a.m. to 10 pm.
Mill Creek Channel
About 5,000 feet of the Mill Creek channel is federally operated and maintained. The locally operated portion of the channel begins at the Mill Creek-Bennington Lake unit and extends six miles through the city of Walla Walla.
Rooks Park
Rooks Park offers visitors a wide variety of recreational opportunities. The 18-acre park includes a reservable picnic shelter, sand volleyball court, playground, horseshoe pit, group fire rings, picnic sites with tables, BBQ grills and accessible restrooms. Large open areas allow for football and soccer games, while small, secluded areas provide a quiet place to enjoy the outdoors. The park is open from 7 a.m. until posted closure hours, sunset. The entrance is open year-round to walk-in traffic, but seasonally closed to vehicles from October 15 to April 1 with reduced amenities.
To reserve the Rooks Park Shelter visit Recreation.gov or call 1-877-444-6777.
** All areas are day use only, no overnight stays or camping**