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Effects of groundwater pumping on agricultural drains in the Tule Lake subbasin, Oregon and California

Scientific Investigations Report 2015-5087

Prepared in cooperation with the Bureau of Reclamation and the U.S. Fish and Wildlife Service
By:
and
DOI:10.3133/sir20155087

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Abstract

Since 2001, irrigators in the upper Klamath Basin have increasingly turned to groundwater to compensate for reductions in surface-water allocation caused by shifts from irrigation use to instream flows for Endangered Species Act listed fishes. The largest increase in groundwater pumping has been in and around the Bureau of Reclamation’s Klamath Irrigation Project, which includes the Tule Lake subbasin in the southern part of the upper Klamath Basin. Agricultural drains on the Klamath Project are an important source of water for downstream irrigators and for the Tule Lake and Lower Klamath Lake National Wildlife Refuges. U.S. Geological Survey regional groundwater-flow model simulations and records of irrigation-return flow pumped from the Tule Lake subbasin into the adjacent Lower Klamath Lake subbasin have indicated that water-level declines from pumping may be causing decreased flow of shallow groundwater to agricultural drains. 

To better define the effect of increased pumping on drain flow and on the water balance of the groundwater system, the annual water volume pumped from drains in three subareas of the Tule Lake subbasin was estimated and a fine-grid, local groundwater model of the Tule Lake subbasin was constructed. Results of the agricultural-drain flow analysis indicate that groundwater discharge to drains has decreased such that flows in 2012 were approximately 32,400 acre-ft less than the 1997–2000 average flow. This decrease was concentrated in the northern and southeastern parts of the subbasin, which corresponds with the areas of greatest groundwater pumping. Model simulation results of the Tule Lake subbasin groundwater model indicate that increased supplemental pumping is the dominant stress to the groundwater system in the subbasin. Simulated supplemental pumping and decreased recharge from irrigation between 2000 and 2010 totaled 323,573 acre-ft, 234,800 acre-ft (73 percent) of which was from supplemental pumping. The response of the groundwater system to this change in stress included about 180,500 acre-ft (56 percent) of decreased groundwater discharge to drains and a 126,000 acre-ft (39 percent) reduction in aquifer storage. The remaining 5 percent came from reduced groundwater flow to other model boundaries, including the Lost River, the Tule Lake sumps, and interbasin flow.

Suggested Citation

Pischel, E.M., and Gannett, M.W., 2015, Effects of groundwater pumping on agricultural drains in the Tule Lake subbasin, Oregon and California: U.S. Geological Survey Scientific Investigations Report 2015–5087, 44 p., http://dx.doi.org/10.3133/sir20155087.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction 
  • Background
  • Study Objectives
  • Methods
  • Agricultural Drain Flow Analysis
  • Groundwater Model Results
  • Potential Implications
  • Study Limitations and Uncertainty
  • Summary
  • Acknowledgments
  • References Cited
  • Appendix A. Model Observation Wells

Additional publication details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Effects of groundwater pumping on agricultural drains in the Tule Lake subbasin, Oregon and California
Series title:
Scientific Investigations Report
Series number:
2015-5087
DOI:
10.3133/sir20155087
Year Published:
2015
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
Oregon Water Science Center
Description:
vi, 44 p.
Country:
United States
State:
California, Oregon
Other Geospatial:
Tule Lake
Online Only (Y/N):
Y
Additional Online Files (Y/N):
N