Date of Award

12-2019

Document Type

Campus Access Thesis

Degree Name

Master of Science (MS)

Department

Environmental Sciences

First Advisor

Alan D. Christian

Second Advisor

Juanita Urban-Rich

Third Advisor

Ellen Douglas

Abstract

The construction of dams to generate power, control river flow, create a water supply, and control flooding has a long history in the United States, particularly in New England. Massachusetts alone has over 3,000 dams, many of which are no longer serving their intended purpose and are being considered for removal and restoration. Previous studies show that dams alter the ecological, hydrological, and water quality within the system and ultimately result in decreased biodiversity of a system. Removal and restoration of failed or obsolete dams became popular due to no financial loss for companies and to increase overall stream ecosystem structure and function. As part of a working group effort, the Mill River near Taunton Massachusetts underwent three dam removals and a dam retrofit since 2010 with the last dam removal occurring in January 2018. In addition to being affected by dams, the Mill River watershed has a variety of land use and land cover (LULC) ranging from mostly forested to more urban LULC which is likely to affect water quality. In this study, we examine the physical, chemical, and biological characteristics of the Mill River system along a headwater to mouth gradient and in association with the dam removals through sampling 10 stations to assess water quality. The overall goal of this study was to examine the effects of dams and land use land cover on the Mill River system. There were four objectives associated with this goal: 1) to evaluate the local and sub watershed land use land cover and impervious cover, 2) to sample and evaluate the physical habitat variables in the Mill River system, 3) to sample and evaluate the chemical habitat variables in the Mill River system; and 4) to sample and evaluate the freshwater macro-invertebrate assemblage variables in the Mill River system. What is driving the water quality of the Mill River: The Urban Stream Syndrome or the Serial Discontinuity Concept? I expected to observe an urban gradient throughout the system and improved physical, chemical, and biological variables at dam removal and restoration stations. Physical habitat assessments, surface water grab samples, and macroinvertebrates were used as proxies to determine the effects of LULC and dam removal on water quality. From this study it became evident that the implementation and removal of dams have direct impact to the water quality of a river system. Physical, biological, and chemical aspects of the Mill River have been altered due to both urbanization and impoundment removals. These outcomes should aid state officials and agencies understand the effects of dam removals in the context of larger scale LULC.

Comments

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