DEVELOPING A WATER BUDGET FOR MORGAN VALLEY, MORGAN COUNTY, UTAH Submitted to GSA Joint Rocky Mountain/Cordilleran Sections Meeting, 18-20 May, 2011, Logan, Utah By Walid Sabbah, Janae Wallace, Mike Lowe, and Kevin Thomas Utah Geological Survey http://gsa.confex.com/data/handout/gsa/2011RM/Paper_187343_handout_137_0.ppt

Rocky Mountain and Cordilleran Joint Meeting (18–20 May 2011) Paper No Rocky Mountain and Cordilleran Joint Meeting (18–20 May 2011) Paper No. 24-4 Presentation Time: 2:35 PM-2:55 PM DEVELOPING A WATER BUDGET FOR MORGAN VALLEY, MORGAN COUNTY, UTAH SABBAH, Walid W., WALLACE, Janae, LOWE, Mike, and THOMAS, Kevin J., Utah Geological Survey, P.O. Box 146100, Salt Lake City, UT 84114-6100, walidsabbah@utah.gov Morgan Valley is a rural area characterized by extensive agricultural activity and increasing population in the Wasatch Range of northern Utah. The purpose of our study is to develop a water budget for the Morgan Valley drainage basin. The inflow component in Morgan Valley consists of precipitation and streamflow crossing into its drainage basin. We used PRISM precipitation grids to get rates and distribution of precipitation. The 10-year (1998-2007) weighted average precipitation rate is estimated at 26.4 inches per year, which is equivalent to 436,000 acre-feet per year. We estimated the 10-year average stream inflow via the Weber River at Devils Slide at 190,000 acre-feet per year using linear regression. Stream inflow at East Canyon Creek has a 10-year average of 35,000 acre-feet per year. Thus, the total inflow into Morgan Valley is 661,000 acre-feet per year. The outflow component in Morgan Valley consists of evapotranspiration, stream outflow from the Weber River at Weber Canyon and Gateway canal, and water used for municipal and industrial purposes. We estimated the average evapotranspiration (ET) based on current water-related land use and natural vegetation patterns. The ET volumes are integrated by multiplying the acreage of each land use and natural vegetation pattern by its specific ET rate. We estimated average ET consumed by irrigated agriculture at 28,400 acre-feet per year, and ET consumed by natural vegetation at 228,000 acre-feet per year, for a total ET of 256,400 acre-feet per year. The 10-year average outflow measured at the Weber River streamflow station at Gateway is 249,000 acre-feet per year and the water diverted to the Gateway canal/tunnel is measured at 93,000 acre-feet per year, for a total stream outflow of 342,000 acre-feet per year. Water outflow used for municipal and industrial purposes is estimated at 1600 acre-feet per year. Thus, the total outflow from Morgan Valley is 600,000 acre-feet per year. The 61,000 acre-feet per year difference in inflow/outflow does not necessarily represent water available for additional use. The water budget imbalance may result from estimation errors in precipitation, evapotranspiration, or streamflow from the Weber River at Devils Slide, and/or number rounding. -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Geological Society of America Abstracts with Programs, Vol. 43, No. 4, p. 73 © Copyright 2011 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.

Morgan Valley Study Area Morgan Valley is a rural area characterized by extensive agricultural activity and increasing population in the Wasatch Range of northern Utah. The purpose of our study is to develop a water budget for the Morgan Valley drainage basin.

Location of Morgan Valley within Weber River Drainage Basin U.S.G.S. Streamflow station

Outcrops of main aquifers in Morgan Valley Weber Canyon/ Gateway T Outcrops of main aquifers in Morgan Valley Devils Slide U.S.G.S. Streamflow station East Canyon Creek

3-D Block Diagram with drainage pattern in Morgan Valley Cottonwood Creek Weber River East Canyon Creek U.S.G.S. Streamflow station

Methods of Study Both inflow and outflow components of water budget are estimated for Morgan Valley drainage basin as follows: The inflow component in Morgan Valley consists of precipitation and stream flows crossing into its drainage basin. We used PRISM Group (Oregon State University) precipitation grids available at http://www.ocs.orst.edu/prism to get the 10-year (1998-2007) average rates and distribution in the study area. We estimated the 10-year average stream inflow via the Weber River at the Devils Slide using linear regression. We estimated the 10-year (1998-2007) average stream inflow at East Canyon Creek from the U.S. Geological Survey national water information system stream flow records available at http://waterdata.usgs.gov/ut/nwis/nwis.

Methods of Study (Cont.) The outflow component in Morgan Valley consists of evapotranspiration, stream outflow from the Weber River at Weber Canyon and Gateway canal, and water used for municipal and industrial purposes. We estimated the average evapotranspiration (ET) based on the consumptive use of the current water related land use and natural vegetation patterns by multiplying the acreage of each land use and natural vegetation pattern by its specific ET rate. We estimated the 10-year average stream outflow measured at the Weber River streamflow station at Gateway and the water diverted to the Gateway canal/tunnel from the U.S. Geological Survey national water information system stream flow records available at http://waterdata.usgs.gov/ut/nwis/nwis. Water used for municipal and industrial purposes is derived from the Utah Division of Water Resources report available at: http://www.water.utah.gov/M&I/PDF/WeberRiver/Weber%202005%20M&I.pdf .

Results of Study The 10-year (1998-2007) weighted average precipitation rate is estimated at 26.4 inches per year, which is equivalent to 436,000 acre-feet per year. The 10-year average stream inflow via the Weber River at Devils Slide is estimated at 190,000 acre-feet per year. The 10-year average stream inflow from East Canyon Creek to Weber River is estimated at 35,000 acre-feet per year. Thus, the overall total inflow from all sources into Morgan Valley is estimated at 661,000 acre-feet per year.

Results of Study (Cont.) The average ET consumed by irrigated agriculture is estimated at 28,400 acre-feet per year, and ET consumed by natural vegetation at 228,000 acre-feet per year, for a total ET of 256,400 acre-feet per year. The 10-year average outflow measured at the Weber River streamflow station at Gateway is estimated at 249,000 acre-feet per year and the water diverted to the Gateway canal/tunnel is measured at 93,000 acre-feet per year, for a total stream outflow of 342,000 acre-feet per year. Water outflow used for municipal and industrial purposes is estimated at 1600 acre-feet per year. Thus, the total outflow from Morgan Valley is 600,000 acre-feet per year.

10-Year average precipitation from PRISM Data Average precipitation rate is 26.4 in/yr. Average precipitation volume is 436,000 acre-ft/yr

Integrated land use and natural vegetation map used for estimating ET Average ET consumed by irrigated agriculture is 28,400 acre-ft/yr. natural vegetation is 228,000 acre-feet/yr. Total ET is 256,400 acre-ft/yr Overall estimated ET rate is 15.5 inch/yr.

Estimated ET rates for dominant vegetation and land use

Summary of Integrated Water Budget

Conclusions and Recommendations Total estimated inflow into Morgan Valley is estimated at 661,000 acre-ft/yr and the total estimated outflow from Morgan Valley is 600,000 acre-ft/yr. A water budget imbalance of 61,000 acre-ft/yr is noticed which could be attributed to estimation errors in precipitation, evapotranspiration, streamflow from the Weber River at the Devils Slide, and/or number rounding. This water budget is an integrated budget for both groundwater and surface water because both are in direct connection via the Weber River in Morgan Valley. I would recommend building groundwater flow model in the future to estimate the hydraulic interconnection and rates of water exchange between groundwater and surface water once enough water level data and pumping are available.