Western Snake River Plain- Treasure Valley Ground Water (p2)
Ground Water Levels
Ground water levels have been measured on a regular basis as a part of the Treasure Valley Hydrologic Project. Over 350 Treasure Valley wells were measured six times in mass measurements. A mass measurement is the measurement of a large number of wells in a short time (in this case, usually within a one-week period). Mass measurements were conducted in spring and fall of 1996, 1998, and 2000 by the U.S. Geological Survey (http://id.water.usgs.gov/). A mass measurement provides ground water level information at one period in time, which is used to determine a potentiometric surface (in an unconfined aquifer the potentiometric surface is the water table). The potentiometric surface is used to determine ground water flow directions.
Shallow Aquifer Water Levels
Shallow Aquifer Water Levels
Interpolation by Scot Urban, IDWR  

In addition, water levels in about 70 wells have been measured on a monthly basis. Hydrographs, drawn from monthly water level data, are a graphic representation of water level data over time for one location.

Ground Water Level Changes
Seasonal changes in ground water levels can range from few to about 10 feet. These seasonal variations depend on the amount and timing of local recharge and pumping.

Ground water levels in most parts of the Treasure Valley have remained relatively constant. A water level change map for the Treasure Valley compares water levels from the period 1969-1976 with water levels in the year 2000.

Water Level Changes (1969/1976-2000)

Original content compiled by Christian Petrich, Margie Wilkins, Tondee Clark, and Tony Morse.
Images by Scot Urban and Shane Bendixsen for Idaho Department of Water Resources
Adaptation for the Digital Atlas of Idaho by Ean Harker- design/html, Kyle Raverty- content, 11-2002.
Information supplied by the Idaho Department of Water Resources; 1301 North Orchard Street Boise, Idaho 83706 (208) 327-7900.