Thermal Heterogeneity and Cold-Water Anomalies within the Lower Yakima River, Yakima and Benton Counties, Washington

Scientific Investigations Report 2021-5140
Prepared in cooperation with Benton Conservation District under Washington Department of Ecology Funding Agreement WRYBP-VER1-BentCD-00004 as part of the Yakima Basin Integrated Plan
By:  and 

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Abstract

Warm water temperatures in the lower Yakima River in central Washington are key limitations to the restoration of Pacific salmon (Onchorhynchus spp.) populations within the Yakima River Basin. Identification of the location and magnitude of cold-water anomalies, which are cooler than ambient river temperatures during summer months, and the processes that create and maintain them is needed to inform salmon restoration efforts within the Yakima River Basin. Longitudinal thermal profiles of nine reaches in the lower Yakima River were surveyed at ambient river velocity during summer 2018 when surface-water temperatures were near their annual maximum and the difference between surface-water and groundwater temperatures was greatest. The profiles were compared to previously published profiles of the same reaches measured in 2001, 2002, 2008, and 2009, and analyzed in the context of hydrologic, geomorphic, and hydrogeologic conditions that may create and maintain cold-water inputs to the river. Cold-water anomalies that departed from expected diurnal increases in water temperature were measured in all nine study reaches and were attributed to diffuse groundwater discharge through the streambed, discrete groundwater discharge at seeps and springs, and cold-water tributaries entering the river. Some cold-water anomalies were measured during repeated surveys in different years, whereas other cold-water anomalies did not persist across surveys. Additionally, some discrete cold-water anomalies were confined to one side of the channel, but others associated with diffuse groundwater discharge were present across the channel for several river miles. Hydrogeologic conditions including the extent and thickness of aquifers connected to the Yakima River, geomorphic conditions including channel gradient, channel geometry, and floodplain extent, and the location of tributaries, irrigation returns, and other surface-water inputs created the large-scale conditions that facilitate the formation and maintenance of cold-water anomalies. Finer-scale geomorphic features such as side channels, gravel-bar alcoves, deep pools, and other locations, where colder water collected and remained relatively unmixed with upstream surface water, were also important factors in the occurrence and distribution of cold-water anomalies. These hydrogeologic and geomorphic conditions, coupled with the alteration of the Yakima River’s hydrologic regime to support irrigation within the Yakima Valley, contributed to the surveyed distribution of cold-water anomalies within the river.

Suggested Citation

Gendaszek, A.S., and Appel, M., 2021, Thermal heterogeneity and cold-water anomalies within the lower Yakima River, Yakima and Benton Counties, Washington: U.S. Geological Survey Scientific Investigations Report 2021–5140, 45 p., https://doi.org/10.3133/sir20215140.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Abstract  
  • Introduction  
  • Purpose and Scope  
  • Study Area  Methods  
  • Results  
  • Discussion  
  • Summary  
  • Acknowledgments  
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Thermal heterogeneity and cold-water anomalies within the lower Yakima River, Yakima and Benton Counties, Washington
Series title Scientific Investigations Report
Series number 2021-5140
DOI 10.3133/sir20215140
Year Published 2022
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Washington Water Science Center
Description Report: v, 43 p.; Data Release
Country United States
State Washington
County Yakima County, Benton County
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
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