2021 - Investigating dam removal as a tool to increase ecological resilience through water quality improvements

Grant Award Year: 
Principal Investigator: 
Allison Roy
Research Description: 
Small, surface-release dams impair natural stream connectivity by disrupting the flow of water, sediment, nutrients, and biota. Many dams built during the 19th and 20th centuries have exceeded their functional lifespan, and as a result, dam removal has become an increasingly prevalent stream restoration method. However, many streams have not been consistently monitored before and after dam removal, and there is a paucity of information regarding how dam removals affect stream ecosystems across different dam, stream, and landscape characteristics. Therefore, we propose to quantify the impacts of dam removals on water quality through assessments of temperature and dissolved oxygen before and after dam removal and assess the potential benefits of removal in the context of climate change. This study will focus on 16 Massachusetts streams with completed or upcoming dam removals. Within upstream and downstream reaches and within impoundments or former impoundments, we will collect continuous temperature and dissolved oxygen data for 1-3 years prior to removal and up to 5 years following removal. We will also collect ancillary habitat data, which, coupled with dam and landscape characteristics, will lead to a better understanding of the factors influencing stream water quality recovery across Massachusetts. To understand dam removal in the context of climate change, we will further investigate how removals may mitigate for predicted temperature increases improve climate resilience. Results from this study will be used to guide the prioritization of dam removal projects and provide critical information to resource managers and public stakeholders regarding the timing and extent of stream recovery following dam removal.