The Spokane Valley-Rathdrum Prairie Aquifer Atlas Preface Contents
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The Spokane Valley-Rathdrum Prairie Aquifer Atlas Preface Contents The Spokane Valley-Rathdrum Prairie Aquifer Atlas presents a compre- Shaded Relief Map ...........................................Front Cover hensive summary of the region’s most precious groundwater resource and Using The is a basic reference of the geographic, geologic and hydrologic characteris- Preface and Contents........................... Inside Front Cover tics of this aquifer. Introduction ........................................................................ 1 Atlas The Atlas is designed in a narrative format supported by graphs, maps Aquifer from Space............................................................. 2 and images. It is intended for broad community use in education, plan- ning, and general technical information. The preparation and publica- Geography........................................................................... 3 tion of the atlas were partially funded by a United States Environmental Aquifer History................................................................... 4 Protection Agency aquifer wellhead protection grant. Climate and Population .................................................... 5 The information was collected and obtained from a variety of sources, If your interest in the Aquifer is including: United States Environmental Protection Agency, Idaho Depart- Geology................................................................................ 6 general, the authors suggest you page ment of Environmental Quality, Panhandle Health District, Kootenai through this document and spend time Geologic Map ...................................................................... 7 County Planning Department (Idaho), Spokane County (Washington), on those pages that attract your United States Geologic Survey and Eastern Washington University. Ice Age ................................................................................. 8 attention. The Spokane Valley-Rathdrum Prairie Aquifer spans two states (Wash- Spokane Floods .................................................................. 9 If you have specific interests, the Atlas ington and Idaho) and lies within three counties (Kootenai, Bonner and is organized into seven sections. Hydrologic Cycle ............................................................... 10 Spokane). Natural resources, such as the Aquifer, that cross political boundaries are often subject to different, and sometimes conflicting, stan- The Aquifer Cycle ............................................................ 11 General information about the dards, protection and uses. This Atlas is a joint effort by agencies in both Aquifer and the region can be found on states to create a holistic representation of the Aquifer as both geologic Exploring the Aquifer ...................................................... 12 pages 1 – 5. feature and a natural resource used daily by more than 400,000 people. Building a Model .............................................................. 13 The geology of the Aquifer, including Political boundaries are absent on the front cover map. The authors in- Viewing the Model ........................................................... 14 the recent geologic events that formed tend the reader first view the Aquifer as a continuous natural feature, the Aquifer, is presented on pages 6 – 9. then investigate the various aquifer elements presented in this Atlas. The Using the Model ............................................................... 15 authors believe that factual information about the Aquifer will generate Discussions of the Aquifer water cycle Depth to Groundwater..................................................... 16 greater public understanding of the region's groundwater and lead to con- are found on pages 10 – 11. tinued protection and wise use of this precious and finite resource. Aquifer Recharge Areas .................................................. 17 Computer modeling of the Aquifer is Aquifer Water Quality ..................................................... 18 presented on pages 12 – 15. Nitrate Contour Maps...................................................... 19 James D. MacInnis, P.E. Jim Blake Brian Painter, P.G. Aquifer water quality and Aquifer Aquifer Task Manager Water Quality Program Aquifer Hydrogeologist Aquifer Issues .................................................................. 20 issues are found on pages 16 – 21. Idaho DEQ Spokane County Idaho DEQ Protecting the Aquifer ..................................................... 21 An Aquifer tour is described on page Aquifer Tour ..................................................................... 22 22. John P. Buchanan, Ph.D. Beatrice B. Lackaff Reanette Boese Professor of Geology GIS Specialist Water Quality Program Glossary & Definitions ...............................................23-24 A glossary of terms used in this Atlas Eastern Washington Univ. Spokane County Spokane County is found on pages 23 – 24. Acknowledgements ............................... Inside Back Cover Printed and distributed in July 2000 Ice Age Paleogeographic Map .....................................Back Cover Introduction The Aquifer Water Quality Monitoring Spokesman-Review, Thursday, May 6, 1909 The sole source of water for most of the people in The first monitoring of the Aquifer water began Spokane County, Washington and Kootenai County, Aquifer in October, 1908 in the City of Spokane (see side Idaho is a high quality underground water body bar article), but detailed water quality testing in SPOKANE’S WATER called the Spokane Valley-Rathdrum Prairie Aqui- Spokane Coeur the Aquifer began much later. Present day water fer. Discovered in 1895, this Aquifer has become d’Alene quality testing validates in much greater detail one of the most important resources in the region, the 1908 sampling results: the Aquifer has excel- PUREST IN WORLD supplying drinking water to more than 400,000 lent water and it remains one of the highest qual- people. The Aquifer has been studied in consid- ity drinking water sources in the nation. Tests Shows Average of Only Seven erable detail since 1977, and the results of these investigations have produced programs and regu- Since 1977, every three months Spokane County or Eight Germs to Centimeter lations designed to insure this aquifer will remain Location of the Aquifer in Washington and Idaho obtains water samples from about 50 wells in Wash- a valued and protected resource for future gen- ington. The Panhandle Health District has taken MONTHLY TESTS ARE MADE erations. samples from about 28 wells in Idaho since 1974. Testing of these quarterly water samples have City Bacteriologist Frank Rose Reports floods deposited thick layers of coarse sediments shown that: Aquifer Formation (gravels, cobbles, and boulders) in this area. The Results – No Colon Bacilli Found The Spokane Valley and Rathdrum Prairie are an- saturated portion of these sediments, where void ! contaminant levels in the Aquifer increase Showing the Spokane water supply purer than cient geologic features that have, for millions of spaces are filled with water, comprises the Aqui- as the water moves westward, the average of American cities, Frank Rose, city years, been slowly formed by water flowing to- fer. Waters from adjacent lakes, mountain ! contaminant levels show a direct relation- bacteriologist, has made a report of tests from the wards the Pacific Ocean. During the last Glacial streams, the Spokane River and precipitation flow city well made monthly since last October. The ship to human activity, Age, between 12,000 and 1.6 million years ago, a through the flood sediments replenishing the tests are simply counts of the number of bacteria ! contaminants are mostly located in the top series of catastrophic floods covered this area as Aquifer. found in a cubic centimeter of water. a result of the rapid draining of ancient Lake few feet in the Aquifer, and, The average count shows only seven or eight Missoula in Montana when ice dams broke. These ! overall contaminant levels have increased germs in that amount of water. The test was made from water taken from the drinking fountain at Location and Flow since 1977. The Aquifer begins in Idaho between Spirit Lake Howard street and Riverside avenue or from water from a faucet in the Rookery building. Speaking of and the south end of Lake Pend Oreille. The Aqui- This monitoring suggests that human activities his tests, Dr. Rose said: fer water flows south until it reaches the middle on the land surface over the Aquifer are deterio- “It can be said that there is no city in the world that has a better water supply than Spo- of the Rathdrum Prairie, then it turns west and rating the aquifer water quality. Contaminants Aquifer Facts flows into Washington under the Spokane Valley. kane. Water which shows 100 germs in a cubic carried to the Aquifer originate as stormwater, centimeter is considered comparatively pure and When the Aquifer water reaches downtown Spo- septic tank leachate, fertilizer leachate, leaking drinkable. I made from four to eight counts The Aquifer has one of the fastest flow rates kane, most of it turns north, flows under the city underground storage tanks and other sources monthly since last October, and the counts in any in the nation, flowing as much as 50 feet per and discharges into the Little Spokane River. that percolate downward from the surface. Even one month was 17 bacteria, while the tests last day in some areas. In comparison,