Monday, April 25, 2016: 2:00 p.m.
Platte River Room (The Westin Denver Downtown)
Built in 1914, the “Tumalo Project” was proclaimed an utter failure upon completion. As the reservoir filled with water diverted from Tumalo creek, sinkholes developed in the reservoir floor and every last drop of captured water disappeared into the ground. Considerable research has been undertaken on the social and political history of the Tumalo Project, but the path of groundwater leaving the reservoir floor has never been confidently assessed. The geology and history of Tumalo Reservoir present unique circumstances to explore its potential as a groundwater recharge site. The hydrogeology of the Deschutes Basin as a whole has been extensively studied (e.g. O’Connor, Gannett, Lite). However, I propose that these works were done at a scale that overlooks the refined detail of flow in the Tumalo Reservoir area, the specifics of which make it particularly suitable as a groundwater recharge site. The need for long term water security, coupled with a history of proactive water management planning in the basin, create an exciting opportunity to enhance understanding of the role of groundwater resources in the Upper Deschutes Basin and the extent to which their sustainable use is possible. The feasibility study for groundwater recharge at the Tumalo site determines the likely path of groundwater out of the reservoir, the availability of surface water for recharge, and incorporates analysis of local groundwater wells. A hydrogeologic assessment is used to determine the most appropriate approach for development of the site: direct aquifer recharge or aquifer storage and recovery. The ecological and economic impacts of the implementation of a groundwater recharge facility are examined. Finally, the Tumalo site is compared to the Anchor Dam site in Wyoming, another “failed” reservoir site, to help direct a model for repurposing similar geological sites into regional assets for long-term water management planning.
