Source Water Profile: Bozeman, MT

Last week when I was in Santa Barbara, CA, I focused my post on the area’s source water. The natural follow-up is a source water profile of Bozeman, MT.

Credit: RJ Zaworski, used with permission.

Bozeman is in the 2,602 sq. mi. Gallatin County, which sits in a scenic valley at the heart of the Rocky Mountains and intersects seven watersheds. The City of Bozeman itself intersects three: the Madison Watershed 10020007 (left highlighted section on map of MT right), the Gallatin Watershed 10020008 (middle highlighted section on map of MT right), and the Upper Yellowstone Watershed 10070002 (right highlighted section on map of MT right).

As explained last week, watershed proper names are followed by a hierarchical string of numbers ranging from 2 to 16 digits called a Hydrologic Unit Code (HUC). HUCs describe the location and identification of a hydrologic area and come from the U.S. Geological Survey’s (USGS) nationwide system for watershed delineation based on surface hydrologic features. Anyone in the U.S. can look up their watershed address using the U.S. Environmental Protection Agency’s (EPA) online tool for locating and defining watershed addresses.

Bozeman’s water profile can be examined by first establishing “what’s in” and “what’s out”. That is, the people served by the City of Bozeman’s public water supply system (PWS) have different source water than those people outside of city limits. According to the Montana Department of Environmental Quality’s (DEQ) Public Water Supply Online Query, the City of Bozeman’s water system serves 32,000 people. These 32,000 residents receive their water from three sources: Hyalite Creek, Sourdough Creek, and Lyman Creek.

Source: Personal correspondence with City of Bozeman Water
Treatment Plant Operator
. Credit: RJ Zaworski.

Both Hyalite Creek (51 sq. mi. drainage area) and Sourdough Creek (33 sq. mi. drainage area) are surface water sources and combine for 80% of the City of Bozeman’s water supply source (40% each; see graphic left). Hyalite Reservoir—also known as Middle Creek Reservoir and constructed in the late 1940s before being expanded in 1993—stores water from Hyalite Creek for current and future use. The reservoir is just over 10 miles up Hyalite Canyon and is a popular recreation area for campers, hikers, boaters, and other outdoor enthusiasts. Sourdough Creek water has not been stored in a reservoir since Mystic Lake Dam breached and was torn down in 1985. Instead, the City of Bozeman’s water system extracts creek water directly from the watershed in Sourdough Canyon. Recent discussions have proposed building a new dam and reservoir on Sourdough Creek to prepare for the growing city’s future water needs.

Lyman Creek, on the other hand, is a groundwater source and accounts for the remaining 20% of the City of Bozeman’s water supply. The creek is located in the southern foothills of the Bridger Mountain range. Unlike Sourdough and Hyalite Creeks, Lyman Creek water is extracted from a fully enclosed spring and is thus classified as groundwater.

These three water sources supply the 32,000 people connected to City of Bozeman’s PWS. But there are about 91,000 (2011 census estimate) residents of Gallatin County. The almost 60,000 Gallatin residents outside the City of Bozeman get their water from groundwater. Other Gallatin County towns—like Belgrade, Three Forks, and Manhattan—have PWSs that rely on groundwater sources. Some use freshwater springs in their supplies, but these are still categorized as a groundwater source for the same reason Lyman Creek is groundwater. In fact, the City of Bozeman is the only PWS in Gallatin County that includes water from true surface water sources.

Finally, the remaining 41,000 (2011 estimate calculated from Montana DEQ’s Active PWS System Data report) Gallatin County residents not connected to established city and towns PWS systems* receive their water through one of two main sources: through a privately-owned well or through a small PWS system.

Source: Personal correspondence with Gallatin Local Water
Quality District Manager and Water Quality Specialist
Credit: RJ Zaworski.

Whether or not a well is privately owned or is classified, licensed, and monitored as a PWS under DEQ hinges on three factors (see chart left): connections, people, and days used. A well must be registered as a PWS if it has 15+ connections and/or serves 25+ people—the PWS must also operate under these conditions for at least 60 days of the year. If a well does not meet these requirements, it is a privately owned well. The distinction between PWSs and private wells matter regarding how they are regulated.

PWSs range in size from the large ones operated by cities to the small ones operated by entities like campgrounds and trailer courts. PWSs are classified into three types:

  • community (C): serves 15+ connections year-round or 25+ people year-round—simply put, it serves the same people every day. e.g., cities and subdivisions
  • non-transient non-community (NTNC): not a community system but serves 25+ of the same people over six months a year—simply put, it serves the same people but not every day. e.g., schools and workplaces
  • transient non-community (TNC): not a community system and does not serve 25+ of the same people over six months a year—simply put, it serves different people every day. e.g., restaurants and motels

    PWS laws and rules can vary depending on its classification.

    Finally, those remaining Gallatin County residents not on any sort of PWS are on privately-owned wells. In stark contrast to PWSs, private wells are not under any regulation from the DEQ. This means water quality testing and monitoring is not required and instead left to the owner’s discretion. While most wells are deep and new enough to likely produce un-contaminated water, some private wells are old and shallow. In either case, it is important private well owners test their water for contamination, which can come in many forms. When a well is deep enough, the groundwater it produces tends to be of good quality—water in Gallatin county rarely has even trace amounts of contaminants like heavy metals and chemicals.

    The risk usually occurs when the well structure (e.g., a well cap) is old or failing and when a well is not dug deep enough. Unfit well structures can leave the water vulnerable to contamination by harmful bacteria, pathogens, and animals. Shallow wells have less opportunity and time to filter out surface water contaminants that seep down into the well. The best way to find out if a private well falls into either of these categories it through water sample testing.

    The Gallatin Local Water Quality District website provides an extensive library of resources for private well owners. The site offers a long list of useful Fact Sheets that cover topics ranging from bacterial contamination in wells to water sampling procedures. The site is scattered with tips about wells, procedures, and tools. There are also directions for testing drinking water quality. Owners can receive discounts on drinking water testing by participating in the Well Educated Program—a program in partnership with the MSU Extension Water Quality Program . MSU Extension also has educational videos for individual well and septic users. And, if online resources still leave questions unanswered or concerns unresolved, give the staff at theGallatin Local Water Quality District a call or email— they are very friendly and helpful.

    (Click to Enlarge) Credit: RJ Zaworski, used with permission.

    Whether a resident of the City of Bozeman, Big Sky, or other places in Gallatin County, your water comes from either groundwater or surface water. Water is collected, stored, transported, treated, distributed, and recovered through a system of water infrastructure (see graphic above). Water connects us all and is the lifeblood for society. The next time we turn on the tap, remember there is a long, organized water system working to ensure not just the availability of water but its quality as well.

    Where does your water come from?

    Special thanks to RJ Zaworski for providing the wonderful graphics for today’s post.

    *note: the 41,000 estimate was calculated from Montana DEQ’s Active PWS System Data report. The report lists all active registered PWSs in Gallatin County. Only a few cities and towns actually have an established “Town of/City of” PWS—Bozeman (32,000), Belgrade (7,000), Manhattan (1,500), Three Forks (1,800), and West Yellowstone (8,535). The remaining towns and settlements in Gallatin County are supported by a series of smaller PWSs operated by various entities ranging from school districts and subdivisions to ranches and gas stations. Numbers estimates are based on the populations served by each PWS in the DEQ report. For example, the City of Belgrade lists a population of 7,000 connected to their PWS. The rest of Belgrade residents either rely on smaller PWSs or private wells (described in blog text).


    Leave a Reply

    Fill in your details below or click an icon to log in: Logo

    You are commenting using your account. Log Out /  Change )

    Twitter picture

    You are commenting using your Twitter account. Log Out /  Change )

    Facebook photo

    You are commenting using your Facebook account. Log Out /  Change )

    Connecting to %s