About the Water Supply

We are fortunate to have an inexpensive, reliable supply of high quality drinking water from a natural underground "reservoir" known as the Lower Portneuf River Valley (LPRV) Aquifer. In general, the water quality is nearly neutral having an average pH factor of 7.7, meaning the water is slightly alkaline (neutral water has a pH factor of 7.0). The water in our system is considered very hard. It contains approximately 21 grains per gallon (or 360 mg/L) of hardness. The hardness is due to dissolved minerals, primarily calcium carbonate, in the water. These dissolved minerals are not harmful to your health, but they can leave water spots which make cleaning more difficult. These minerals precipitate into small grains in ice cubes and create a white film in hot coffee or tea.

Pocatello and Chubbuck both take 100% of our water from the LPRV aquifer. Our aquifer is extremely vulnerable to contamination from human activities. It is our only source of drinking water for the foreseeable future and is an irreplaceable resource. Preventing pollution is the first priority in protecting our groundwater supply. It is always more expensive to clean up aquifer contamination than to prevent it.

The lower Portneuf Valley aquifer is vulnerable because of several factors:

1) varied urban, residential, industrial, and agricultural land uses with the potential to contaminate the water supply occur directly over the aquifer;

2) water and contaminants originating at the surface can move quickly to the water table because the aquifer has minimal natural protection (thin soil cover, shallow water table, highly permeable Bonneville gravels between the surface and water table);

3) numerous artificial sources of recharge associated with urban / residential land uses (drain wells, ditches, septic leach fields) accelerate the movement of contaminants to the water table;

4) the highly permeable aquifer spreads contaminants rapidly, making it difficult to clean up contamination once it has entered the aquifer;

5) the lower Portneuf Valley aquifer and its immediate tributary aquifers comprise the effective sole drinking water source for Pocatello, Chubbuck, and northern Bannock County.


Chubbuck's drinking water comes from four wells drilled into the Lower Portneuf River Valley Aquifer. They are located throughout the city. This water is very high quality and the only treatment given is to chlorinate it. Well No. 4 does have a special treatment system however for tetrachloroethylene (PCE or PERC).


Pocatello's drinking water is obtained from deep wells strategically placed in various locations throughout the City, which pump water from the Lower Portneuf River Valley Aquifer.

The City's 19 wells have a daily pumping capacity of more than 50 million gallons of water, and the 14 reservoirs have a storage capacity of 23.6 million gallons. Over 15,000 service line connections are used to supply residents and businesses with water.

A complete emergency plan exists to protect Pocatello's water supplies. For example, the City maintains truck and trailer mounted generators capable of powering the systems pumps on a limited basis. During an emergency situation, maintaining an adequate supply will be given top priority. (As an interesting historical note, the city filled all storage tanks to full capacity prior to December 31, 1999, in case any Y2K problems occurred.)

In providing reliable water service, the City incurs significant expense related to every-day operating needs of the department and long-term capital needs. These capital and operating expenditures are constantly increasing because of the deterioration of existing facilities, increasing regulatory requirements and inflation. Because the City recognizes the importance of replacing the aging infrastructure, a portion of their revenues are set aside in a special account for capital improvement projects. There are approximately 248 miles of water main lines in the system. Last year they replaced 1.89 miles, which is 0.8 percent of the system (the national average is 0.6 percent per year). However, even with such an aggressive approach for replacing aging infrastructure, at the current rate it will take approximately 130 years to update the system.