The present day Missouri River Treatment Plant was constructed in 1960 and is located North East of Helena. Raw water is supplied by an underground pipe from the Helena Valley Regulating Reservoir. The regulating reservoir is part of the Helena Valley Irrigation District and is only a supplier of water. The regulating reservoir and its water are not owned by the city and we must purchase all water that is used.
The water is treated with a variety of chemicals to clean the water and purify it. After that it is pumped into a 20" steel line at 185 PSI to flow to town. The water is fed into the system and the excess is stored in Malben and Woolston reservoirs. That is why it is called the Malben - Woolston system. When the plant is operating the water is generally separated with the Missouri water on the east side of town and the Ten Mile water on the west. During the winter the Missouri plant is shut down and all of the water for this system is from the Ten Mile.
The Ten Mile Creeks headwater is located above Rimini, MT. It flows through Rimini where several feeder creeks join it below Rimini. The City of Helena has headgates on the these creeks so that the best water can be taken to supply the Ten Mile Water Plant. Headgates are located on Ten Mile, Beaver, Minnehaha, Moose and Walker creeks. The headgates divert the water into a concrete pipe line that flow directly to the Ten Mile Water Plant.
The City of Helena owns the first and second water rights on the Ten Mile Creek. The first water right is for 325 miners inches of water per day and the second is for 225 miners inches. This is approximately 8.9 million gallons of water per day. We are not allowed to take more than this allotment nor are we allowed to average our usage.
If there is not enough water supplied by Ten Mile Creek, additional water can be added from Chessman or Scott reservoirs. This water is not counted against our water rights.