City and Borough of Juneau
There are two water sources for the areawide water system. The Last Chance Basin (LCB) well field on Gold Creek is the primary source. This well field typically supplies a total demand of about 3.0 million gallons per day (MGD). This source was first built in 1959, with additional wells drilled and other improvements made in 1976 and 1990. Chlorination is the only treatment this water receives.
The secondary source for the water system is Salmon Creek. This source is provided in conjunction with the Alaska Electric Light and Power Company's (AEL&P) Salmon Creek power generation plant. The power plant is fed by a reservoir located in the upper reaches of the Salmon Creek watershed; the AEL&P generator is located near sea level. The CBJ pumps water after it passes through the generator facility. Treatment includes chlorination, and pH and alkalinity adjustment with soda ash before the water enters the distribution system. This source came on-line in 1984 when AEL&P rehabilitated the lower Salmon Creek power house.
Salmon Creek is an intermittent source due to seasonal high turbidity and annual maintenance on the generator by AEL&P. Salmon Creek typically supplies about one third of the water areawide, when on-line.
When both sources are available, residents north of Hospital Drive are served by water from Salmon Creek, while residents south of Hospital Drive and all of Douglas Island are served by Last Chance Basin water.
Water System Features (1984 vs. 2006)
Presently there are a total of nine reservoirs throughout the areawide water system.
* These reservoirs also serve as chlorine contact tanks, where chlorine is added and given time to react with any pathogens.