Boise Front Ground Water Management Area

The Boise Front Low Temperature Geothermal Resource is located in Boise City and Ada County in southwestern Idaho. The area was designated on June 15, 1987. The order identified the resource of concern to be ground water from a depth greater than 300 feet and/or a temperature greater than 85° fahrenheit(F).

The geothermal resource has been used for heating for over 100 years. However, increased development during the mid-1980’s more than doubled the diversion volume from pre-1983 levels. Water level declines of up to 30 feet from 1983 to 1987 have been documented in some of the geothermal wells.

The Director signed a Management Policy for the Boise Front Ground Water Management Area on June 3, 1988. The policy identified specific goals and actions. The goals are (1) Protect the existing users; (2) Allow full use of the geothermal resource; (3) Provide clear management policies; and, (4) Stabilize depletions. An advisory committee has not been formed. IDWR works closely with the major geothermal users within the area and regularly reviews ground water data.

An order establishing a five-year moratorium, an action identified in the Management Policy, was issued on June 11, 1988 preventing new development or increased use of the resource. The moratorium was extended in 1993, 1998, and 2003; it is currently in place until November 25, 2008.

A number of recent events have occurred within the Boise Front GWMA:

1. In 1999, the City of Boise drilled an injection well for underground disposal of the used geothermal water from its system. Previously, the used water had been put in the Boise River. A long-term monitoring well near the foothills has shown a 20 feet rise in water level. The water level rise has been attributed to the injection of the water by City of Boise.

2. Ground Water District 63S, also known at the Stewart Gulch Water District, was created by an order of the Idaho Department of Water Resources on December 5, 1989. The northern boundary was changed on September 21, 1995. Sometime in the early 1990s a water master was hired to oversee the District. In about 1996, the District became inactive as requested by the users.

   In 2002, IDWR received a request to reinstate the Water District. The district was reinstated and a water master was appointed in April, 2003. The water master’s responsibilities are to measure eight wells in the District on a regular basis, maintain the data and provide annual reports. In addition to the data collection and management responsibilities, the water master will also administer water in the event of a call for water by one of the District’s members.

3. An agreement signed in 2002 between the geothermal water users and IDWR allowed the City of Boise to increase its production by 15%. A component of the agreement included a geothermal study to evaluate the resource. The study was completed in 2003 and is available here.

Ground water levels in wells are measured according to a monitoring plan that was put into place in 2002. Current hydrographs of the wells can be viewed using the Online Ground Water Level Database or figures showing annually-updated hydrographs for selected wells can be viewed here.

A Review of Boise Front Geothermal Monitoring Data for Water Year 2005 can be viewed at here.