Document Details

Geohydrology and Numerical Model Analysis of Ground-Water Flow in the Goose Lake Basin, Oregon and California

David S. Morgan | December 15th, 1988


From the early 1970s until 1981, ground-water development in the Goose Lake basin underwent rapid growth. The number of new wells constructed and total State-permitted ground-water withdrawals for irrigation reflect the increase in ground-water development that occurred during this period.

A strong agricultural economy spurred much of the development by providing incentives to expand irrigated acreage and modernize irrigation methods (from gravity to sprinkler systems). The drought of 1976-77 also encouraged farmers to develop ground water as a supplemental source to less reliable surface-water supplies used in the past.

A preliminary assessment of the basin by OWRD staff (R. B. Almy, Oregon Department of Water Resources, written commun., 1981) concluded that, based on rates of water-level decline and increases in withdrawals, further and more detailed study of the basin was warranted. Between 1975 and 1982, water-level declines in some OWRD observation wells ranged from 0.5 to 3 feet per year, while permitted ground- water withdrawals increased at an average rate of 4,000acre-feetperyear(acre-ft/yr). Similarwater-level declines and increases in withdrawals occurred near Davis Creek on the California side of the basin during this period. This prompted a 1982 assessment of ground-water conditions by the California Department of Water Resources (California Department of Water Resources, 1982).

At the time of OWRD’s assessment it was felt that too little information on the actual rates of ground-water use, recharge, and the geohydrology of the aquifer system was available to allow proper management of the resource. If the rates of water-level decline and ground-water withdrawal that existed prior to 1981 had continued, issuance of new permits for ground-water use potentially could have been halted in order to determine if the Goose Lake basin should be designated as a “criticalground-water area.” Sucha designation would allow the State of Oregon to limit the use of ground-water resources in the area.

However, overdraft of the ground-water resource became a less urgent issue after 1982, when a downturn in the agricultural economy, combined with rising costs of electrical power (and thus pumping), resulted in a widespread reversion to dryland farming and low-water-use crops.

Adverse agricultural market conditions halted the growth of ground-water development in the basin; these trends could conceivably reverse in the future to spur growth again. In recognition of this potential and the need to build an understanding of the basin in order to properly manage future ground-water development, OWRD entered into a joint program of study with the U.S.Geological Survey. The first of a proposed series of ground-water basin assessments, this 1-year study was started in 1986 with the goals of characterizing the nature, extent, and properties of water-bearing rocks within the basin and describing and quantifying the components of recharge to, and discharge from, the basin.

Additionally, this study was designed toe valuate the adequacy of available and readily collectable information to quantitatively describe the geohydrology of the basin. If this information was found to be inadequate, the study would also identify the data needed to better describe, understand, and manage the ground-water resource.

Keywords

Groundwater Exchange, modeling, transboundary aquifers