Canyon Ferry Village Public Water System
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CANYON FERRY VILLAGE PUBLIC WATER SYSTEM PWSID# MT0000243 SOURCE WATER DELINEATION AND ASSESSMENT REPORT Report Date: 10/23/03 Contact Person: Budd Breining Canyon Ferry Village – Bureau of Reclamation 7661 Canyon Ferry Road Helena, MT 59601 Phone: (406) 475-3310 Table of Contents SECTION Page INTRODUCTION......................................................................................................................... 1 PURPOSE ...................................................................................................................................... 1 LIMITATIONS ............................................................................................................................. 1 PUBLIC WATER SUPPLY INFORMATION........................................................................... 1 GEOGRAPHY............................................................................................................................... 2 GEOLOGY .................................................................................................................................... 3 WATER QUALITY ...................................................................................................................... 3 DELINEATION............................................................................................................................. 3 INVENTORY................................................................................................................................. 4 SUSCEPTIBILITY ASSESSMENT ............................................................................................ 4 TABLE 1: HAZARD RANKINGS OF SIGNIFICANT POTENTIAL CONTAMINANT SOURCES IN THE CANYON FERRY VILLAGE PWS INVENTORY REGION. ................ 4 TABLE 2: SUSCEPTIBILITY ASSESSMENT RATINGS OF SIGNIFICANT POTENTIAL CONTAMINANT SOURCES IN THE CANYON FERRY VILLAGE PWS INVENTORY REGION...................................................................................................................................... 5 SUMMARY.................................................................................................................................... 5 REFERENCES .............................................................................................................................. 6 APPENDICES ............................................................................................................................... 7 APPENDIX A: AREA WELLS.................................................................................................. 8 APPENDIX B: SITE LAYOUT ................................................................................................ 9 APPENDIX C: CONCURRENCE LETTER............................................................................ 10 FIGURES FIGURE 1. CANYON FERRY VILLAGE VICINITY MAP FIGURE 2. CANYON FERRY VILLAGE WELL LOCATION MAP FIRUGE 3. CANYON FERRY VILLAGE REGIONAL GEOLOGY FIGURE 4. CANYON FERRY VILLAGE INVENTORY REGION FIGURE 5. CANYON FERRY VILLAGE REGIONAL LAND USE i Source Water Delineation and Assessment Report for Canyon Ferry Village (PWSID# MT0000243) Introduction Carolyn DeMartino, a Water Quality Specialist with the Montana Department of Department of Environmental Quality (DEQ), and Amy C. Schlatter, a DEQ intern, completed the Canyon Ferry Village Source Water Delineation and Assessment Report. Purpose The Canyon Ferry Village Public Water System (PWS) Source Water Delineation and Assessment Report has been completed to meet the technical requirements of the Montana Source Water Protection Program (DEQ, 1999) and the Federal Safe Drinking Water Act (SDWA) amendments of 1996 (P.L. 104-182). The Montana Source Water Protection Program is intended to be a practical and cost- effective approach to protecting public drinking water supplies from contamination. A major component of the program is “delineation and assessment”. Delineation is a process of mapping source water protection areas, which contribute water used for drinking. Assessment involves identifying locations or regions in source water protection areas where contaminants may be generated, stored, or transported, and then determining the relative potential for contamination of drinking water by these sources. Limitations The terms “drinking water supply” or “drinking water source” refer specifically to the source of Canyon Ferry Village public water supply and not to any other public or private water supply. Also, not every potential or existing source of groundwater or surface water contamination in the area has been identified. Identification of potential contaminant sources is limited to those regulated for this class of PWS and is generally based on readily available information and reports. Every effort has been made to ensure completeness, however, unregulated activities and unreported contaminant releases may have been overlooked. The delineation method utilizes simplifying assumptions that may not fully represent complex ground water flow systems but is intended to be conservative and protective of public health. Public Water Supply Information The Canyon Ferry Village PWS, a transient non-community public water supply, is located on the northeast corner of Canyon Ferry Lake, just 1.2 miles east of Canyon Ferry Dam (Figure 1). The legal location is SW1/4NE1/4NW1/4, Section 3, T.10 N., R.1W. (Figure 2). The Canyon Ferry Village PWS has discontinued the use of surface water 1 currently utilizes one groundwater well, Well #2 (WL004), to supply water through five service connections to the Bureau of Reclamation office, a warehouse, garage, carpenter shop, and the visitors center The PWS serves a transient population of 25 people in the summer (DEQ SDWIS Database, 2003). There is no available well log or water rights record for this well at either the Montana Bureau of Mines and Geology (MBMG) Ground Water Information Center (GWIC) or the Department of Natural Resources and Conservation (DNRC). Information for Well #2 is based on information provided by Budd Breining, the water operator, a sanitary survey completed in October 2001 by the Cadmus Group, an Operation and Maintenance Evaluation from January 1995, and the DEQ SDWIS database. This PWS is supplied by one well with a 6-inch casing and submersible pump. According to Budd Breining, six fiberglass pressure tanks control the cycling of the well pump and provide 85 gallons of storage each with 35 gallons of drawdown capacity. The water runs through two small filters, in parallel, for sand removal and then is chlorinated with sodium hypochlorite. (Cadmus, 2001). According to the 1995 Operation and Maintenance Evaluation, the well yield is 50 gallons per minute (gpm). Well depth and lithology are unknown. Based on another area well log, the well appears to be completed in semi-confined Tertiary sediments that are overlain by Quaternary sediments (Appendix A). The source water sensitivity to potential contaminant sources for this aquifer type is moderate. An estimated water demand of 250 gallons per day (gpd) in the summer was determined for this PWS by referencing the water usage value of 10 gpd for the transient population (EPA, 1991). The water demand during winter months is 50 gallons per day (B. Breining, September 2003). Geography The Canyon Ferry Village PWS is located on the northeast side of Canyon Ferry Lake approximately 20 miles east of Helena. Canyon Ferry Lake was created when Canyon Ferry Dam was constructed on the Missouri River near the small settlement of Canyon Ferry. The Big Belt Mountains bound the Missouri River Valley to the northeast and the Spokane Hills bound the valley on the southwest side. Prominent river-cut terraces are present at several levels (Mertie, Fischer, and Hobbs, 1951). Climate in the Canyon Ferry Lake area is considered semi-arid. The average monthly high and low temperatures in the vicinity range from 84.0° F to 52.2° F in July and 31.3° F to 13.6° F in January. Precipitation averages 11.36 inches annually concentrated in the months May through September. Looking at historic snowfall data, it appears that snowfall in the Canyon Ferry Village area ranges between 26 to 38 inches annually (WRCC). 2 Geology Sedimentary rocks in the Canyon Ferry Lake area are comprised of rocks that range in age from Precambrian to Recent (Figure 3). The Precambrian rocks are composed of limestone and shale of the Belt Series. Tertiary lake deposits in the area are composed of volcanic debris. Recent-aged (Quaternary) river alluvium consisting of gravel, sand, and silt are found on the valley floor. Igneous rocks consisting of monzonite and granite that intruded sedimentary deposits are most likely Tertiary-aged. Lava flows and basalt dikes were intruded during the Miocene epoch. Historically, some copper, gold, and platinum mining occurred in the Canyon Ferry Lake vicinity. Sapphires have also been mined in this vicinity. Most neighboring mines in the region have been abandoned. (Mertie, Fischer, and Hobbs, 1951). Water Quality The Canyon Ferry Village PWS is classified as a transient non-community public water supply; therefore, the only regulated contaminants that are required to be routinely monitored in the drinking water include nitrate and microbial pathogens. In the last five years, nitrate plus nitrite levels in this public water supply well ranged between 0.0 milligrams per liter (mg/L) to 0.52 mg/L (DEQ SDWIS database). These levels are well below the EPA mandated maximum contaminant level (MCL) of 10 mg/L.