JETTE MEADOWS LANDOWNERS ASSOCIATION PHASE I Phase I-PWS ID # MT0003100 JETTE MEADOWS LANDOWNERS ASSOCIATION PHASE II Phase II-PWS ID # MT0003101 PUBLIC WATER SUPPLIES SOURCE WATER DELINEATION AND ASSESSMENT REPORTS Lake County, Montana 24 APRIL 2006 PREPARED FOR: JETTE MEADOWS LANDOWNERS ASSOCIATION PHASE I JETTE MEADOWS LANDOWNERS ASSOCIATION PHASE II PUBLIC WATER SUPPLIES Robert Gambrel, Administrative Contact Eva Gambrel, Financial Contact Clay A. Sloan, Operator PO Box 34 Polson, Montana 59860 Phone: 406/ 883-0911 or / 885-7556 PREPARED BY: MONTANA DEPARTMENT OF ENVIRONMENTAL Jette Meadows Landowners Assoc. Phase I & II SWDAR (combined) MT0003100 & MT0003101 QUALITY Source Water Protection Program Jeffrey Frank Herrick, Hydrogeologist P.O. Box 200901 Helena, Montana 59620-0901 ii Jette Meadows Landowners Assoc. Phase I & II SWDAR (combined) MT0003100 & MT0003101 iii Jette Meadows Landowners Assoc. Phase I & II SWDAR (combined) MT0003100 & MT0003101 EXECUTIVE SUMMARY This Source Water Delineation and Assessment Report was prepared under the Federal Safe Drinking Water Act and the Montana Source Water Assessment Plan. The Montana Department of Environmental Quality (DEQ) is ensuring that assessments are completed for all public water systems in Montana. The purpose of these reports is to provide information so that the public water system operator, consumers, and community citizens can begin developing strategies to protect your source of drinking water. The information that is provided includes the identification of the area most critical to maintaining safe drinking water, i.e., the Inventory Region, an inventory of potential sources of contamination within this area, and an assessment of the relative threat that these potential sources pose to the water system. Jeffrey Frank Herrick with DEQ’s Source Water Protection Program completed this report. The drinking water for the Jette Meadows subdivisions is actually supplied by 2 different public water supplies. The eastern Phase I subdivision (PWS# MT0003100) is supplied by 1 well that is located at the south end of the development. The western Phase II subdivision (PWS# MT0003101) is supplied by 1 well that is located along Ranch Road. Based on the sanitary surveys, well logs, and the depth of the wells, it appears that a deep bedrock aquifer underlies most of the area. In the area of Jette Meadows, this aquifer is mantled by glacial till. The Phase I Well 1 (inactive) and the Phase II Well 1 production wells are both installed into the fractured bedrock aquifer. It appears that the Phase I Well 2 (located off Meadow Road) is installed into the bottom of this till unit and probably right above the bedrock. This mantle of glacial till appears to be acting as a confining unit. In accordance with the Montana Source Water Protection Program criteria (1999), the aquifer (source water) is considered to have a low sensitivity to potential contaminant sources since it is both a deep bedrock aquifer and a confined aquifer. Sensitivity is defined as the relative ease that contaminants can migrate to source water through the natural materials. Three types of source water protection management regions for the Jette Meadows Landowners Assoc. Phase I & II public water systems were mapped as part of this assessment. They are the control zone, inventory region, and the recharge region. Potential sources of contamination were identified within each of these three regions and the results are as follows: • The control zones were delineated as a 100-foot radius around each of the wells and all sources of potential contaminants should be excluded in this region. The goal of management in the control zone is to avoid introducing contaminants directly into the water supply's well or immediate surrounding areas. No potential contaminant sources were identified within the control zones. • Since the source water is confined, the inventory region for the wells consists of a 1000-foot radius circle around the wellheads. The inventory region should be managed to prevent contaminants from reaching the well before natural processes reduce their concentrations. Significant potential contaminant sources that were identified within the inventory region include: areas of grazing land, septic systems and their associated drainfields, and the highway. • The recharge region was delineated based upon topographic mapping of the watershed above the public water supplies. The goal of management in the recharge region is to maintain and improve water quality over long periods or increased usage. Within this deep aquifer, groundwater generally flows from the edges of the basin southeastward toward Flathead Lake. Groundwater flow beneath the developments is thought to be from northwest to southeast. Recharge to the deep aquifer is occurring in the high ground north of Ranch Road and Bull Pine Road (inclusive of the Jette Lake iv Jette Meadows Landowners Assoc. Phase I & II SWDAR (combined) MT0003100 & MT0003101 Susceptibility is the potential for a public water supply to draw water contaminated by inventoried contaminant sources at concentrations that would pose concern. Susceptibility is determined by considering the hazard rating for each potential contaminant source and the existence of barriers that decrease the likelihood that contaminated water will flow to the public water supply well intakes. The susceptibility analysis provides the community and the public water system with information on where the greatest risk occurs and where to focus resources for protection of this valuable drinking water resource. The Jette Meadows subdivisions public water supplies’ wells have a moderate to low susceptibility to spills that may occur along the highway. These wells have a very low susceptibility to septic systems with drainfields in the inventory regions. The costs associated with contaminated drinking water are high. Developing an approach to protect that drinking water resource will reduce the risks of a contamination event occurring. In this report, we have summarized the local geology and well construction issues as they pertain to the quality of your drinking water source. We have identified the area we believe to be most critical to preserving your water quality (the Inventory Regions) and have identified potential sources of contamination within that area. In addition, we provide you with recommendations (i.e., Best Management Practices) regarding the proper use and practices associated with some common potential contamination sources. The report makes a case for doing whatever is possible to reduce development of individual homes (with septic systems) in the area of groundwater recharge or promoting the installation of Level 2 septic treatment systems associated with these houses. We believe public awareness is a powerful tool for protecting drinking water. The information in this report will help you increase public awareness about the relationship between land use activities and drinking water quality. Refer to the figures found in Appendix A of this document to better understand the spatial relationship of the area. The susceptibility of the PWS to the significant potential contaminant sources is discussed on Tables 9, 10, and 11. Overall, there appear to be very few nearby threats to the production well beyond the onsite septic systems for the development and the highway. v Jette Meadows Landowners Assoc. Phase I & II SWDAR (combined) MT0003100 & MT0003101 TABLE OF CONTENTS EXECUTIVE SUMMARY.........................................................................................................IV TABLE OF CONTENTS............................................................................................................VI INTRODUCTION .........................................................................................................................9 Table 1. Jette Meadows Landowners Assoc. Phase I & II PWS Contacts..............9 BACKGROUND..........................................................................................................................10 The Community....................................................................................................................10 Geographic Setting...............................................................................................................10 Description of the Source Water.........................................................................................11 The Public Water Supply ....................................................................................................11 PWS Facilities ..............................................................................................................12 Table 2. PWS Facilities Summary.........................................................................12 PWS Well Information .................................................................................................12 Table 3. PWS Well Information.............................................................................13 DELINEATION...........................................................................................................................15 General Discussion...............................................................................................................15 Table 3. List of Geologic and Hydrogeologic Investigations................................15 Table 4. List of Geologic and Hydrogeologic Maps .............................................16 Table 5. Source Water