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This map shows the topographic relief of the Portneuf watershed in relation to Pocatello and Chubbuck. The cities are located in the lower drainage basin of the Portneuf River, which is a tributary of the upper Snake River. The upper Portneuf drainage consists of 1,160 square miles, while the lower basin drains 145 square miles. The total Portneuf watershed covers 1,300 square miles. |
| The upper and lower drainage
basins are separated from one another by a bedrock upthrust to the south that creates a
narrow basement-to-surface channel called the Portneuf Gap. The majority of the watershed is comprised of upland
forests and lowland agricultural acreage.
The Lower Portneuf River Valley aquifer receives all of its recharge water from the upper and lower Portneuf watersheds. The southern portion of the Bannock Range supplies 2/3 - 3/4 of total known recharge from snowpack in the Mink Creek and Gibson Jack Creek sub-basins. The remainder of the aquifer's known recharge comes from groundwater flowing through the Portneuf Gap, originating in the Upper Portneuf River Valley aquifer. Very little recharge is thought to originate as leakage from the Portneuf River. Overall, the surface drainage supplying the LPRV aquifer is of good quality. Take a look at the Environmental Protection Agency's Portneuf watershed IWI score for an overview. Find the LPRV aquifer on the map above, then CLICK to zoom in on |
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