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Date Permissions Signed

8-5-2022

Date of Award

Summer 2022

Document Type

Masters Thesis

Department or Program Affiliation

Freshwater Ecology

Degree Name

Master of Science (MS)

Department

Environmental Sciences

First Advisor

Bodensteiner, Leo R., 1957-

Second Advisor

Helfield, James M.

Third Advisor

Eckmann, Madeleine

Abstract

Anthropogenic development in river floodplains has diminished the extent groundwater and surface water interact. This interaction plays an important role in the formation of floodplain habitats that provide essential refuge for stream biota when extreme seasonal conditions arise. To address the need for more off-channel habitat in the floodplain, a novel strategy of habitat construction was implemented by the Yakama Nation in the Methow River Basin. At two locations, groundwater infiltration galleries were installed in relic side channels disconnected from the mainstem by infrastructure. These installations collect subsurface flow and drain it to excavated channels connected to the mainstem channel at the downstream end. These projects aim to enhance off-channel habitat for overwintering juvenile salmon and trout by creating habitat with groundwater as the primary water source. The groundwater influence should offer stable thermal conditions during seasonal extremes. In this study, I compared these two unique projects with a more common side channel restoration project dominated by mainstem channel flow as the main water source. I documented seasonal changes in water temperature and dissolved oxygen at three sites and explored differences in fish and insect communities. I also performed aquatic and riparian habitat assessments. I found that physical habitat was comparable among the sites, but those with groundwater galleries had more consistent water temperatures and a greater abundance of insects and fish. The use of groundwater infiltration galleries may be an effective technique for mitigating the loss groundwater-influenced habitat.

Type

Text

Keywords

Groundwater, infiltration gallery, off-channel habitat, salmon recovery, habitat restoration, side channel, water temperature, dissolved oxygen, aquatic insects

Publisher

Western Washington University

OCLC Number

1340427284

Subject – LCSH

Fishes--Effect of habitat modification on--Washington (State)--Methow River Watershed; Floodplain ecology--Washington (State)--Methow River Watershed; Groundwater temperature--Washington (State)--Methow River Watershed

Geographic Coverage

Methow River Watershed (Wash.)

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.

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