Groundwater Hydrology of the Upper Deschutes Basin and Its Influence on Streamflow

Landscape controls on the distribution and ecohydrology of central Oregon springs

“…Despite their importance for local livestock economies and ecosystems, low-discharge springs are poorly studied in comparison with their higher discharge counterparts. There are no other studies of small springs systems in Oregon, compared with numerous publications describing larger springs and their supporting aquifer systems (Gannett et al, 2001(Gannett et al, , 2003Gannett, Lite, La Marche, Fisher, & Polette, 2007;James et al, 2000;Manga, 1996Manga, , 1997Manga, , 1999Manga, , 2001Meinzer, 1927;Whiting & Moog, 2001). Even studies of large, regional spring systems commonly do not describe the species supported by them.…”

“…Many of the springs we inventoried flowed less than 50 m before the water re-infiltrated into the soil. In contrast, precipitation falling on higher permeability terranes such as Quaternary lava flows has been shown to infiltrate to deep regional aquifer systems more effectively, resulting in longer flow paths integrating larger recharge areas with fewer opportunities to discharge through springs at the land surface (Gannett et al, 2001;Manga, 1997). For example, temperature and isotope data collected from Opal Springs on the Crooked River about 11 km from its confluence with the Deschutes River indicate that the source is tens of kilometres away in the Cascade Range (James et al, 2000).…”

“…Weathering, hydrothermal alteration, secondary mineralization, and diagenesis generally reduce the permeability of volcanic rocks with time (Freeze & Cherry, 1979). Secondary permeability resulting from faulting, fracturing, or dissolution can have a strong effect on groundwater flow in some settings (such as Karst regions), but permeability in the Deschutes Basin is more strongly controlled by original rock lithology and depositional processes (Gannett et al, 2001;Lite & Gannett, 2002). Although a range of hydraulic conductivity values have been estimated in each of the terranes, the upper and lower limits and average hydraulic conductivity differ among terranes and markedly decrease with increasing age.…”

“…Seven landscape-scale variables that describe the hydrogeologic and landscape settings of the springs and that may influence spring discharge type, discharge amount, and water chemistry were derived from other spatial datasets and summarized for each spring. These Gannett, 1984;Gonthier, 1985 Early Tertiary volcanic, volcaniclastic, and volcanic sediment deposits of the Clarno and John Day Formations 5-140 0.003-0.3 Low Gannett, 1984;Gonthier, 1985 Basalt flows of the Miocene Columbia River Basalt Group 5-900 0.3-40 Medium Ely et al, 2014;Gannett, 1984;Gonthier, 1985;Vaccaro et al, 2015 Quaternary surficial deposits 9-1,400 8-46 Medium Gannett, 1984;Gonthier, 1985;Morgan, Hinkle, & Weick, 2007 Late Tertiary volcanic, volcaniclastic, and volcanic sediment deposits of the Deschutes Formation (and their age equivalents) 20-23,000 3-680 High Gannett et al, 2001;Gannett, Lite, Risley, Pischel, & La Marche, 2017;Gonthier, 1985 Quaternary volcanic deposits of the Cascade Range and Newberry Volcano 50-74,000 1-300 High Gannett et al, 2001Gannett et al, , 2017Gates & Gannett, 1996;Manga, 1997, Saar & Manga, 2004 Note. Transmissivity and hydraulic conductivity values were estimated in the cited sources using a variety of methods including analysis of specific capacity data from well logs, published aquifer tests, and model analysis.…”

“…USGS, 2017). Along the lower 22 km of the Crooked River, there is regional groundwater discharge of about 28 m 3 s −1 , providing roughly two thirds of the mean annual flow (Gannett & Lite, 2004;Gannett, Lite, Morgan, & Collins, 2001;James, Manga, Rose, & Hudson, 2000). Above this lower reach, there are large seasonal flow variations characteristic of a run-off-dominated stream system, with mean flows ranging from 42.7 m 3 s −1 in April to 0.31 m 3 s −1 in August (USGS gage 14080500, period of record 1941-1959 prior to construction of major impoundments; Friday & Miller, 1984).…”