An investigation of the hydrologic system in Heber and Round Valleys was conducted to improve understanding of the surface-water and ground-water hydrology and the effects caused by changes in recharge.  Ground water is present in consolidated rocks and in unconsolidated valley-fill deposits, but the principal ground-water reservoir is in the unconsolidated valley-fill deposits.

Recharge to the unconsolidated valley-fill deposits in Heber Valley from unconsumed irrigation water, stream infiltration, subsurface inflow from consolidated rocks, and precipitation is estimated to be 154 cubic feet per second.  Discharge is by leakage to Deer Creek Reservoir, by springs and seeps, by seepage to the Provo River and other streams, by evapotranspiration, and by pumping from wells.

Recharge to the unconsolidated valley-fill deposits in Round Valley from stream infiltration, precipitation, unconsumed irrigation water and subsurface inflow from consolidated rocks is estimated to be 11 cubic feet per second.  Discharge is by springs and seeps, by evapotranspiration, and by pumping from wells.

Seasonal water-level fluctuations of up to 30 feet occur primarily because of changes in recharge from unconsumed irrigation water.  Water levels generally are highest during June or July when recharge from irrigation is at a maximum and lowest during the winter when irrigation is absent and recharge is at a minimum.  Water levels in wells near Deer Creek Reservoir respond to changes in the reservoir level.

A modular, three-dimensional, finite-difference ground-water flow model developed by McDonald and Harbaugh (1988) was used to simulate the hydrologic system in the unconsolidated valley-fill deposits of Heber Valley.  Model simulations indicate that decreased recharge to the unconsolidated valley-fill deposits causes a decrease in discharge to springs and seeps, streams, and leakage to Deer Creek Reservoir.  Future decreases in ground-water recharge caused by changing from flood- to sprinkler-irrigation methods will cause future decreases in ground-water discharge that will be offset to some extent by increased surface-water flows.