Bozeman has been getting surface water from Sourdough Creek since 1917 and from Hyalite Creek since 1957. In the Hyalite creek drainage, the City has 5,900 acre-feet of water storage in Hyalite Reservoir (image below).

Water from the Sourdough and Hyalite drainages is treated at the Sourdough Water Treatment Plant. The current Sourdough Water Treatment Plant (image below) went online in March of 2014 with a maximum capacity of 22 million gallons per day. The Sourdough Water Treatment Plant processes about 75% of the water requirement for the City.

At the Sourdough Water Treatment Plant, the first step in treatment is grit removal. During this process the water goes through a vortex which concentrates sand and grit at the bottom where it is removed. Next is the coagulation/flocculation/sedimentation process. A coagulant is added so that particles combine to form flocs. The flocs then settle to the bottom of the pretreatment basins (image below) and are removed.

After sedimentation, the water passes through strainers that remove particles larger than 300 microns (a human hair is about 60 microns) to protect the membrane filters from debris. Next the water is filtered through microfiltration membranes (image below) that remove particles larger than 0.1 microns (a cryptosporidium cyst is about 3.5 microns). After filtration, the water is disinfected with chlorine. The pH is then adjusted in an effort to inhibit corrosion of pipes. Lastly, the water is fluoridated to aid in the prevention of tooth decay.

The floc that settles out of the pretreatment basins are sent to the gravity thickener where they are condensed to produce a concentrated sludge. The sludge is pumped out to drying beds (image below) where the final dewatering occurs through evaporation. The dry solids that are leftover are then hauled offsite. The water and particles that are released during backwashes of the membrane filters are recycled back to the beginning of the pretreatment process.

Lyman Creek was first used as a surface water source in 1889. The water from the Lyman Creek source is groundwater, so it does not need to be filtered like our surface water sources. It is chlorinated and fluoridated, then introduced to the distribution system. Production from the Lyman spring varies through the year, peaking in early summer at 3.7 million gallons per day.

The City of Bozeman has four water storage reservoirs. Combined, our reservoirs store up to sixteen million gallons of water to serve the daily needs of our City and provide backup in case of fires or other emergencies. Lyman Creek reservoir can hold 5.2 million gallons of water. The other three reservoirs hold water from the Sourdough Water Treatment Plant and utilize gravity so that no booster pumps are needed to maintain water pressure throughout the system.