Water Usage

In addition to supporting complex ecosystems, the waterways of the Flathead Watershed fill reservoirs with drinking water and water to irrigate agricultural lands in Canada and the U.S. Without this water, many of the areas now cultivated in the watershed would be unsuitable for agriculture.  The availability and distribution of high quality water have been important factors in the settlement of Montana, with most of the state’s population concentrated along major river valleys. The state ranks third in the U.S in miles of stream, sixth in number of lakes, and fourth in total acreage of land. 

Figure 4.5: Well pump. Source: Todd Berget

Montana’s streams range from large year-round flowing rivers to small intermittent streams that flow only when recharged by precipitation or groundwater to ephemeral streams that flow only during large runoff events. Lakes range from large persistent natural freshwater systems to saline basins that evaporate completely each year. These surface waters contribute to uses including public water supplies, domestic household water, irrigation, livestock, industry, mining, and tourism. Our wellbeing, much of our economy, and a number of our recreational activities depend on the abundance and quality of water.

Cultural traditions, laws, and regulations work in concert to govern water distribution among Flathead Watershed water users. The guiding management principles stem from the Montana State Constitution which states “All persons are born free and have certain inalienable rights. They include the right to a clean and healthful environment and the rights of pursuing life’s basic necessities, enjoying and defending their lives and liberties, acquiring, possessing, and protecting property, and seeking their safety, health, and happiness in lawful ways. In enjoying these rights, all persons recognize corresponding responsibilities.”

Water pollution is a national, state-wide, and watershed-wide issue that threatens our opportunity to fully enjoy a clean and healthful environment. And as a headwaters state, we have a national responsibility to ensure citizens living downstream will also receive clean water from our state.

Drinking and Household Water
Well Construction and Maintenance | Resources |

Drinking water in the Flathead Watershed is supplied by municipalities through an intricate network of water engineering. Some residents still pull surface water from Flathead Lake. But, most of the residential and agricultural developments in the watershed rely on municipal and on-site groundwater wells that are fed by shallow aquifers. Glacial meltwater that permeated huge areas of gravel formed our aquifers ten thousand years ago. These shallow aquifers contain a complex network of organisms that naturally cleanse the waters.  Numerous pollutants—such as nutrients (nitrogen and phosphorous), oil, gas, and heavy metals—can jeopardize the health of the aquifers. In addition, failing septic systems can contribute a variety of pollutants to groundwater, including coliform bacteria and a wide range of pharmaceutical and personal care products (PPCPs).

Wetlands, riparian areas, and floodplains that overlay these aquifers provide a buffer that filters out some or all of the nutrients and pollutants before they reach the water source. Well-defined shallow aquifers include 1) the Delta region between the north shore of Flathead Lake and the Flathead River, 2) the Evergreen aquifer between the Flathead and Whitefish Rivers, which is the most developed shallow aquifer, 3) the east side between the Flathead River and the foothills of the Swan Mountains, and 4) the Lost Creek fan west of the Stillwater River near the Salish Mountains. Most other shallow aquifers have developed along stream valleys.

Planning and Protecting Your Well
Wells capture groundwater from aquifers, making it available for our use. There are several consequential considerations regarding yield and placement of private wells. Drinking water from wells is a valuable resource that requires proper planning and protection. Like surface water, ground water can become contaminated by naturally occurring elements, compounds, and metals; household, agricultural, and industrial chemicals; pharmaceuticals; bacteria and viruses from septic systems and animal waste; and fertilizers, pesticides, and household chemical waste. Contaminants percolate through the soil from the land surface near the well casing, or  they enter groundwater directly through improperly constructed wells or unsealed pipes. The greater the distance put between a well and potential contamination, the better.

The first step in protecting a well is made in the planning stage by selecting an appropriate site for placement of the well. Generally, rules require domestic drinking water wells be located 100 feet away from any septic drain field or associated mixing zone, including your own and your neighbors’. County health departments and the State often recommend additional criteria regarding well placement in relation to livestock, fuel storage, and hazardous chemicals.

Some wells require permitting and may be subject to area-specific regulations and restrictions, and any parcel of less than 20 acres (8 hectares) likely requires a specific approved well location. It is imperative to understand all requirements and restrictions before planning a well. The county health and environmental health departments can provide assistance. All wells should be drilled by a contractor licensed through the Board of Water Well Contractors.

Once a well is installed, proper well maintenance and land management uses around the well will help protect the water supply from contamination. Water testing provides valuable information regarding the ongoing condition of the water. It is the only way to determine if the water quality has changed for any reason. Water should be tested after flooding, if there is any noticeable change in the color or odor of the water, or if pipes or well caps show any signs of deterioration or corrosion. At a minimum, annual testing for bacteria (such as coliform) and nitrates is recommended. Further tests are available for a number of basic water quality characteristics.

Figure 4.6: Well contamination sources profile. Source: Montana Department of Natural Resources Conservation
Figure 4.7: Well contamination sources site survey. Source: Montana Department of Natural Resources Conservation

Well Construction and Maintenance
Reprinted with permission of Tammy Crone, Gallatin Local Water Quality District
Constructing Your Well

Employ a Montana licensed well driller. Consult with DNRC on current well construction standards and insure that proper compliance with those standards is maintained during well drilling:

  • Well casing should extend at least 18 inches above the natural ground surface or at least 2 feet above the maximum 100-year flood level, whichever is greater.
  • Well should be fitted with a sanitary (weather-tight, insect-proof, vented) well cap upon completion.
  • Well should be properly grouted during construction to provide a layer of protection from land surface contamination.
  • Wells designed to withdraw more than 35 gallons/minute, or greater than 10 acre-feet of water/year, require a water right permit from DNRC before construction.
  • File a Notice of Completion with DNRC once your well has been completed and put to use. It is required by law.

The land-use and waste-disposal practices near your well can have a profound effect on your water quality. If you have an existing well, options for protecting your water may be limited to controlling potential contamination sources nearby.



Graphics courtesy: Gallatin Local Water Quality District

Figure 4.8: Poorly protected well. Source: Gallatin Local Water Quality District
Figure 4.9: Properly protected well. Source: Gallatin Local Water Quality District

Maintaining Your Well

  • Test your water annually for bacteria, nitrates and other contaminants of concern. Also test if there is a change in your water’s taste, odor, or appearance; after the well system is serviced; or after a flooding event.
  • Visually inspect the well casing, well cap and the ground surface around the well casing annually. Any holes or cracks found should be repaired immediately to prevent entry of dirt, surface water, insects or other contamination.
  • Replace a non-sanitary well cap with a sanitary one.
  • Some older wells are connected to household plumbing systems or livestock watering areas without backflow regulators. Backflow prevention devices should be installed to correct this. Backflow can also occur through hoses connected to well hydrants. When filling an outside water container or chemical mixing tank, always maintain an air gap between the container and the fill hose. Otherwise, back-siphoning to the well and direct contamination of your drinking water may result.
  • Have your septic system pumped regularly and operate it properly.
  • Hazardous materials—paint, oil, pesticides, household chemicals, Pharmaceuticals & Personal Care Products (PPCPs), etc.—should not be stored, mixed, or spilled near the well. Never dispose of these down the drain.
  • Limit the use of lawn and garden chemicals. Excess product moves easily through the soil to ground water and contributes to high nitrate levels which may have adverse health impacts. Apply these chemicals sparingly and follow manufacturer’s application instructions.
  • When landscaping, avoid planting flowers, trees, and shrubs near your well since they will require watering and fertilizing.
    Hire a Montana licensed well driller for any well modification or closure.
  • Don’t pile snow, leaves, dirt or other materials next to or on top of your well.
  • Keep your well records in a safe place (well log, maintenance records, and water test results).

Figure 4.10: Non-sanitary well cap. Source: Gallatin Local Water Quality District
Figure 4.11: Sanitary well cap. Source: Gallatin Local Water Quality

Flathead Basin Commission
Montana Bureau of Mines and Geology MBMG)
Groundwater Information Center (GWIC)

Groundwater Information Center
Montana Department of Environmental Quality (DEQ)
Permitting & Compliance
Board of Water Well Contractors

Montana Department of Natural Resources Conservation (DNRC)

Water Well Drilling for the Prospective Well Owner


For more information, send email to info@flatheadwatershed.org or info@flatheadcore.org.
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