Ground-Water Hydrology of the Upper Deschutes Basin, Oregon

1. Ground-Water Hydrology of the Upper Deschutes Basin, Oregon Kenneth E. Lite Jr., Oregon Water Resources Department

2. Study Area Upper Deschutes Basin Study Area Oregon

3. Major Parts of a Regional Ground-Water Study • Geologic framework • Geologic controls on ground-water flow • Hydrologic budget • Recharge • Discharge • Flow-system • Flow directions • Water-level and discharge fluctuations • Computer Modeling

4. Hydrogeologic Units • Quaternary Sediment • Cascade Range and • Newberry Volcano Deposits • Deschutes Formation Inactive Margin Deposits Ancestral Deschutes River Deposits Arc Adjacent Plain Deposits Proximal Volcanic Deposits • Pre-Deschutes Formation Deposits

5. Recharge Estimate Average Annual Recharge, 1993-1995

6. Hydraulic Head Distribution Generalized Water-Table Mapof the Upper Deschutes Basin

7. To Streams Estimated Stream Gains and Losses > 500 cfs gain 100 to 500 cfs gain 50 to 100 cfs gain 10 to 50 cfs gain 0 to 10 cfs gain 0 to 10 cfs loss 10 to 20 cfs loss 20 to 50 cfs loss 50 to 100 cfs loss Measurement endpoint

8. Precipitation and SW trends 250 225 200 175 150 125 Discharge (Cubic Feet per Second) Cumulative Departure (Inches) 100 75 50 Discharge of Fall River 25 Cumulative Departure from Average Precipitation at Crater Lake 0 -25 1930 1940 1950 1960 1970 1980 1990 2000 Climate-Driven Fluctuations in Ground-Water Discharge At Fall River

9. SW and GW trends 250 40 Monthly mean discharge, Fall River Depth to water, Well 15S/10E-8ACD 200 60 150 80 100 100 50 120 0 140 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 Climate-Driven Fluctuations in Ground-Water Discharge and Water Levels in Wells Fall River Discharge (CFS) Depth to Water in Well (Feet)

10. Natural recharge occurs primarily in the Cascade Range. It takes time for the recharge pulses to propagate across the basin.

11. 1993 1994 1995 1996 1997 1998 1999 The response to recharge pulses is delayed and attenuated with increasing distance from the Cascade Range. Water-Level (2 feet per mark)

12. Summary • Our present understanding of the ground-water hydrology is based on years of careful data collection and analysis. • The unique hydrologic character is due to highly permeable volcanic deposits juxtaposed against older low-permeability deposits, and the incision of the Deschutes River down to these older deposits. • The ground-water system of the upper Deschutes Basin helps maintain relatively even stream flow, however ground-water levels and streamflow vary markedly in response to climate cycles. • Ground-water pumped from wells and used consumptively will mostly be reflected in reductions in ground-water storage and diminished ground-water discharge to streams.

13. http://or.water.usgs.gov/projs_dir/deschutes_gw/index.html Simulation of Regional Ground-Water Flow in the Upper Deschutes Basin, Oregon, by Marshall W. Gannett and Kenneth E. Lite Jr., WRIR 03-4195. Ground-Water Hydrology of the Upper Deschutes Basin, Oregon, by Marshall W. Gannett, Kenneth E. Lite, David S. Morgan and Charles A. Collins, WRIR 00-4162. Geologic Framework of the Regional Ground-Water Flow System in the Upper Deschutes Basin, Oregon, by Kenneth E. Lite Jr. and Marshall W. Gannett, WRIR 02-4015. Chemical Study of Regional Ground-Water Flow and Ground-Water/Surface-Water Interaction in the Upper Deschutes Basin, by Rodney R. Caldwell, WRIR 97-423. Ground-Water and Water-Chemistry Data for the Upper Deschutes Basin, Oregon, by Rodney R. Caldwell and Margot Truini, WRIR 97-197.