Dolores River Groundwater Monitoring: A Senior Thesis

By senior geology major Melissa Boley

Roughly 80,000 dams have been constructed in the United States in the past two centuries. These impoundments seriously affect downstream environments in many ways, some of which are still not fully understood. It is understood that dam construction significantly impacts riparian ecosystems that are related to groundwater levels, but less is directly known about how impoundment directly impacts recharge and drawdown rates of floodplain aquifers. The Dolores River is a mountain stream originating from the San Juan Mountains of Southwestern Colorado, and has been impounded by McPhee Dam. For my senior thesis, I am studying how the construction of McPhee Reservoir has impacted the Dolores River and its adjacent floodplain aquifers. With the help of the Fort Lewis College Geology and Biology Department, my advisor Dr.Gary Gianniny, and my friends and family, nine groundwater monitoring wells have been installed in three different pointbars along the Dolores River. There are two sites below McPhee Reservoir and one site above. Each site has three wells (combination of galvanized steel and PVC pipe) with pressure transducers, which were installed on elevation transects perpendicular to the river. Each site also contains a barometric pressure transducer, which will be important in accounting for atmospheric pressure in my results. I am currently working with the Dolores River Dialogue, an organization working to improve downstream ecological conditions though the operational management of the McPhee Reservoir, as well as Dr.Cynthia Dott and Dr. Julie Korb from the Fort Lewis College Biology Department, in order to further the scope of this study to dam operational management and riparian vegetation.

Melissa with transducer
Melissa with her transducers in the Dolores River floodplain

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