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Date Permissions Signed

12-3-2013

Date of Award

2013

Document Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Environmental Sciences

First Advisor

Matthews, Robin A., 1952-

Second Advisor

Bodensteiner, Leo R., 1957-

Third Advisor

Landis, Wayne G.

Abstract

During the summer of 2009, the Bellingham drinking water treatment plant experienced severe reductions in filtration rates, resulting in mandatory water restrictions. Since then, summer water filtration rates continued to approach critical levels. In 2011, I conducted a study to investigate the phytoplankton and ambient water quality patterns in Lake Whatcom source water to see if any parameters could be used to predict low water filtration rates. In addition, I evaluated water quality and phytoplankton cell densities at different depths at the intake located in Lake Whatcom to see if drawing source water from different depths could help reduce water filtration problems. Water quality and algae samples were collected at the treatment plant screen house and at the intake in Lake Whatcom between June 15 and November 30. During the study period, 62 algal taxa were collected at the screen house. Aphanocapsa/Aphanothece (Cyanobacteria) dominated the algal cell density and Cyclotella and Stephanodiscus (Bacilliariophyta) dominated the algal biovolume, but no single taxon was a unique predictor of low water filtration rates. Among the water quality parameters, nitrate/nitrite had the strongest correlation with filtration rates. Hierarchical cluster analysis was conducted using the first four principal components generated using water quality and algal taxa cell densities, omitting filtration rates and redundant variables. Hierarchical clustering resulted in two distinct clusters that were associated with low and high filtration rates. The samples from the low filtration rate group were characterized by higher water temperatures, conductivities, and alkalinity levels; lower turbidities, nitrate/nitrite and ammonium concentrations; higher cell densities of Aphanocapsa/Aphanothece, Stephanodiscus, Fragilaria, Synedra, Thalassiosira, Naviculoid group, Scenedesmus, Chlamydomonas, Elakatothrix, Cryptomonas, Gymnodinium and Peridinium. Cell morphological characteristics, including mucilage production, elongated cell and presence of fiber threads, were shared by many of the dominant algae in the low filtration rate group and may contribute to the slow filtration. The water quality and phytoplankton community were similar between the screen house and intake sites. In addition, the water column at the intake site was usually unstratified and well-mixed, creating high degree of uniformity in the water quality and phytoplankton data at all depths. Varying the intake depth, which is currently at 10 meters in Basin 2 of Lake Whatcom, is not likely to reduce the effects of problematic algae on water filtration rates.

Type

Text

Publisher

Western Washington University

OCLC Number

865088243

Digital Format

application/pdf

Geographic Coverage

Whatcom, Lake (Wash.)

Genre/Form

Academic theses

Language

English

Rights

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

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