Document Type

Thesis

Date of Degree Completion

Fall 2018

Degree Name

Master of Science (MS)

Department

Resource Management

Committee Chair

Anthony Gabriel

Second Committee Member

Carey Gazis

Third Committee Member

Clay Arango

Abstract

River side-channels provide habitat for threatened fish, and restoring such habitats is a goal of resource managers. Resource managers use side-channel reconnection projects to increase the quality and quantity of aquatic floodplain habitat, and evaluating the effectiveness of reconnection is a crucial and often neglected part of these projects. The purpose of this research was to collect baseline data to determine if and how floodplain connectivity affects water quality and quantity in side-channel habitat on the Yakima River. This research compared seasonal differences in habitat quality between connected and disconnected channels by evaluating bi-weekly measurements of surface water quality and water level stage, as well as seasonal changes in water table elevation measured in monitoring wells, before a floodplain reconnection project. Water quality parameters assessed included temperature, dissolved oxygen, conductivity, turbidity and pH. Isotope concentrations of 18O and 2H, and temperature and conductivity profiles of side-channels were used to help detect groundwater/surface water interactions. Statistical analyses, geographic information systems, and computer models were used to detect significant changes or relationships in the data. Significant seasonal variations in water quality and water table elevations were found among and between connected and disconnected side-channel sites. Water quality and quantity in the floodplain are expected to increase after the project. These data and analyses will provide vital information to assess future floodplain restoration and management.

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