Upper Kittitas County
Upper Kittitas County Groundwater Study
Planned activities for June 2012 - September 2012
- Thermal profiling of stream reaches will be conducted to estimate areas of groundwater discharge and to document potential summer thermal habitat for salmonids.
- Monitoring of the monthly groundwater levels will continue.
- Groundwater-level data will be examined and an initial water-level contour map will be created. The map will delineate generalized directions of groundwater flow.
- Additional wells will be sampled for geochemical constituents later this spring or in early summer.
- Available geochemical data will be interpreted to help refine our understanding of groundwater movement in the study area.
- Consistent and reproducible methods to estimate permit-exempt well use will be further developed.
- USGS will investigate the potential use of aerial photography/imagery to determine outdoor water use.
- Domestic water-use per capita rates based on published estimates and indoor/outdoor usage will be established and those rates and census population data will be used to estimate domestic groundwater use for permit-exempt wells.
- Input files with well construction information and drillers log lithology will be prepared for construction of hydrogeologic cross sections. Lithologic sections will be created and hydrogeologic units will be correlated and identified.
- The geologic history and geologic units of the study area will be described.
- Borehole surveys of 5-7 wells are planned to investigate the role of fractures in controlling groundwater flow in the fracture-dominated bedrock terrane.
- Some of the geophysical tools that will be used during the survey include a caliper log to document borehole diameter, acoustic televiewer log to locate and map the depth and orientation of significant fractures in the well bores, borehole flow meter logs to ascertain water entry and exit from significant water-bearing fractures, gamma and resistivity logs to help ascertain lithology of bedrock strata, and fluid resistivity, conductivity, and water temperature logs to further determine potential location of water-bearing fractures within the well bores.
- USGS's Deep Percolation Model (DPM) of the study area will be updated to provide estimates of daily values of precipitation, evapotranspiration, and recharge for areas of the Roslyn structural basin.
- In June, USGS will present results of the Yakima River basin groundwater study and appropriate uses of the numerical model to the Yakima County Commissioners.
- USGS will coordinate with Washington State Department of Ecology and Kittitas County to plan a public meeting to discuss the status and initial findings of the study.
Status update for October 2011 - May 2012
- Discharge measurements from the low-flow seepage investigation were published in the 2011 Annual Water Data Report.
- A monthly groundwater-level monitoring network was established.
- The measurement of monthly groundwater levels will capture the spatial and temporal aspects of groundwater movement throughout the study area.
- Major-ion and trace-element concentrations were sampled from 15 wells. These naturally occurring elements reflect the chemistry of recharge water that enters an aquifer, dissolution of minerals into groundwater during the movement of groundwater through aquifers, and other reactions between groundwater and aquifer solids.
- Selected sites were sampled for carbon-14, SF6, and noble gases during field visits in May, 2012.
- The geochemical signature of groundwater provides (1) information about the aquifers through which groundwater passes and (2) qualitative understanding of groundwater time-of-travel.
- USGS compiled relevant and available geographic information system (GIS) data for the estimation of permit-exempt water use. Data include census block information, Public Water service area boundaries, National Land Cover Data, and Kittitas County tax parcel data.
- A preliminary method to analyze and refine data was tested and established. A GIS tool was used to redistribute populated census blocks not being served by public water suppliers based on developed land-use categories.
- Initial selection of wells to use in the construction of hydrogeologic cross sections was completed.
- USGS presented "Water quantity issues in the Yakima River basin," at Curriculum for the Bioregion conference at Central Washington University
Status update for October 2010 - September 2011
- A low-flow seepage investigation was conducted to determine streamflow gains and losses. Discharge was measured at 44 stream locations throughout the study area (http://wa.water.usgs.gov/projects/kittitasgw/seepage.html).
- Distributed temperature sensor (DTS) measurements were collected to measure the temporal pattern of groundwater discharge to Little Creek.
- A spring mass water-level measurement and well inventory were conducted in April-May. Water-level data were collected at 196 wells (http://wa.water.usgs.gov/projects/kittitasgw/sites_wl.htm).
- A subset of 43 wells measured in the spring was revisited in August for water-level measurements.
- Well information for all inventoried wells was input into the USGS's National Water Information System (NWIS). In addition to the measured water levels, all historical water levels for the visited wells were entered. The entered information was also checked and verified.
- Accurate well locations and identification of their respective logs are essential in the characterization of the hydrogeologic setting. The measurement of groundwater levels is an important component to develop a better understanding of the groundwater-flow system in the study area.
- Stable isotopes of water (hydrogen and oxygen) were sampled at 196 wells during the spring well inventory.
- Precipitation collectors were installed at 3 locations for analysis of stable isotopes.
- In August, USGS collected samples from 56 wells for stable isotopes of water and tritium. These samples capture much of the spatial variability of stable isotopes and tritium across the upper Kittitas basin. Samples for stable isotopes also were collected at 40 stream locations.
- Stable isotopes of water are useful for determining groundwater recharge areas and understanding groundwater/surface-water interactions. Tritium decays over time and thus is useful for providing a general understanding of groundwater age and the rate of groundwater movement.
- Precipitation-Runoff Modeling System (PRMS) watershed models were updated to current conditions for estimation of water budgets in the upland areas. PRMS estimates daily values of precipitation, evapotranspiration, streamflow, and recharge.
- USGS presented two study updates at public meetings with the Kittitas County commissioners and a presentation for the Upper Kittitas Ground Water Study Advisory Committee.
- Study approaches and initial results were presented to Central Washington University Geology Department and the Ice Age Floods Institute in Ellensburg.
Results of the mass water-level measurement were published in "Groundwater levels for selected wells in Upper Kittitas County," by Lisl Fasser and Ray Julich (http://pubs.usgs.gov/ds/649/)