U.S. Department of the Interior U.S. Geological Survey Groundwater Study For Malad and Bear Rivers Drainages, Box Elder County Bear River Water Conservancy District 102 West Forest Street Brigham City, Utah April 23, 2012

Role of U.S. Geological Survey Provide hydrologic understanding specifically designed to inform decisions about groundwater development and surface-water rights  Cooperative Study Division of Water Rights U.S. Geological Survey  Length of Study March 2012 to March 2015  Funding $360,000

Hydrologic System Groundwater ENTERS (recharges) the subsurface flow from the surrounding mountains and irrigated fields Groundwater EXITS (discharges) the subsurface along the Bear and Malad Rivers, springs, Bear River Bird Refuge, and Great Salt Lake L.J. Bjorklund and L.J. McGreevy, 1974, Ground-Water Resources of the Lower Bear River Drainage Basin, Box Elder County, Utah, State of Utah Technical Publication 44

How Groundwater Pumping Affects Surface Water The effect of groundwater pumping is a reduction in natural discharge from the aquifer, an increase in recharge to the aquifer, or some combination Controlling factors include:  Location of pumping wells  Permeability of the aquifer  Where natural discharge occurs  Where recharge occurs

Analysis Tool is Regional Groundwater Flow Model Simulates the interactions between streams, groundwater, springs, pumping, irrigation, and mountains Includes:  Permeability of the consolidated rocks in the mountains  Permeability of the sand-silt-clay in the valley  Recharge from snow and rain  Recharge from irrigation  Discharge to wells, springs, streams, and plants

Groundwater Model Reflects Conditions in Early 1970’s Modify to current conditions  Locations and amounts of irrigation  Additional wells  Discharge to streams and springs  Consideration of field drains

Collection and Examination of Additional Data Land owner cooperation for access to wells and other measurements sites is essential  Spring flows  Stream flows  Chemistry  Water levels  Field drains  Land-use changes

Groundwater Model Will Be Used To Create “Capture Map” San Pedro River, Arizona Capture maps shows the amount of water that is “captured” or diverted from flowing through the aquifer to the river, due to pumping at a well Example An estimated 60% to 70% of water pumped from wells located in yellow areas would normally flow through the aquifer and discharge to the San Pedro River

Contacts Lynette Tim Bert