.. :2. Our File: 82 G/3 #2. T 8 A.P. Kohut Senior Geological Engineer Groundwater Sect ion Water Management Branch. Date: August 30, 1985.

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1 T 8 AP Kohut Senior Geological Engineer Groundwater Sect ion Water Management Branch Date: August 30, 1985 Our File: 82 G/3 #2 Re: Groundwater Levels - Banes Lake Areia At the request of Mr JH Dyck, Regional Water Manager of Region 4, Kootenay, an office study was undertaken to assess the possible causes of reported groundwater level declines in the Baynes Lake area It has been reported that work carried out by BC Hydro at the Elk0 Dam may have caused lower groundwater levels iat Baynes Lake In this study all available long-term records of precipitation at Grasmere (Station No ) were collated by cumulative precipitation departure method (Kohut et al, 1982) with the data of groundwater levels of Observation Well No 182 Air photography of the Baynes Lake area was used to examine the topographic and local geologic conditions This memorandum reviews groundwater conditions in the area and makes recommendations for further considerations Geographic and Geologic Settings The study area (Figure 1) lies within the Rocky Mountain Trench and is less than 30 km north of the international boundary It is located on the eastern shore of Lake Koocanusa about 20 km northwest of Grasmere The deposits underlying the study area consist mainly of fluvioglacial gravel and sand and drumlinized morainal deposits of till (Ryder, 1981) Soils (Figure 2) overlying the fluvioglacial deposits have been mapped as Flagstone Sandy Loam while those overlying the morainal deposits have been mapped as Wycliffe Silt Loam (Kelley G Sprout, 1956) Baynes Lake and a number of neighbouring ephemeral lakes lie within depressions underlain by the fluvioglacial deposits Groundwater Conditions Available well log information for the area shows that subsurface conditions are highly variable Groundwater conditions in the Baynes Lake area have been described previously by Kohut (1976) Groundwater occurs under,water table conditions at shallow depths within the sand and gravel fluvioglacial deposits overlying glacial till and/or lacustrine clay These deposits vary up to 50 feet in thickness but are somewhat irregularly distributed, occurring in the topographically low areas :2 W-372

2 'r, AP Kohut August 30, 1985 Adjacent topographic mounds or ridges in the area are not mantled or may only be thinly covered by outwash material Groundwater also occurs at greater depths in the region within sand and/or gravel deposits underlying clay or till From well records these permeable deposits appear to have an irregular distribution and are not always present within the section penetrated by deep drill holes This complexity in the local geology stresses the needs for adequate and careful drilling, screening and developing techniques There is no guarantee, however, that individual wells will always obtain an adequate domestic supply at a reasonable depth (200 feet) The prospects may be good in one lot but somewhat doubtful in another Reported non-pumping water levels in the area range from 1 to 97 feet below ground surface (Figure 3) Several drilled wells near the drumlin south of Baynes Lake have encountered dry holes A summary of wells logs in the area is shown in Table 1 The shallow water table aquifer appears to be recharged from inflow from the neighbouring ephemeral lakes and infiltration from precipitation Water levels in wells appear to be reasonably close to the same level as these lakes and ponds (Johanson, 1976) 'fie shallow sand and gravel deposits underlying Baynes Lake extend northeasterly as far as the Elk River in the vicinity of the Elk0 Dam Recharge of these gravels upstream of the Elk0 Dam may occur but detailed hydrogeological investigations involving test drilling would be required to determine the hydraulic relationships in this area Reported groundwater well yields range Metween 02 L/s (3 gpm) and 95 L/s (150 gpm) Three reported dry wells were drilled south of Baynes Lake The reported highest yield occurs in wells near the lakes or the potential recharge area Mr Knight's well in Lot 8, Block 22, DL 132 was drilled in an area underlain by glacial till and silt has been reported dry Further drilling particularly along the eastern boundary of Mr Knight's property at the lowest elevation could possibly encounter water within 250 feet although there is no guarantee of this Hydrological Data Precipitation data for the study area were compiled from the "Meteorological Observations in Western Canada" provided by Surface Water Section, Ministry of Environment, with the aid of a-computer to tally the monthly total precipitation for Station No , Grasmere Groundwater levels for the nearest available observation well (Well No 182) in Marysville were examined 3

3 - 3 - AP Kohut August 30, 1985 A cumulative precipitation departure graph based on normal precipitation (Environment Canada, 1982) and groundwater level hydrograph were plotted in Figure 4 to assess the trend of groundwater fluctuations A cursory examination of water equivalents for the snow courseiat Station No 2C07 of the Columbia Basin was made to assess the snowpack conditions during the period Evaluation and Interpretation of Data Data from meteorological stations and the existing observation well within the Rocky Mountain Trench provide some indication of the probable trend of groundwater levels in the Baynes Lake area The cumulative precipitation graph in Figure 4 suggests that groundwater levels within the Rocky Mountain Trench would be rising during the period when precipitation was above normal Fluctuations in groundwater levels, however, can be induced by man's activities or natural hydrologic phenomena (Freeze 6 Cherry, 1979) The reported low water level in the study area may be due to a number of factors such as local interference, changes in groundwater flow regime, rate of recharge and discharge, evapotranspiration and consumption Records of snowfall at Station No 2C07, Fernie East,(Table 2) display a similar trend as the total precipitation variation in Grasmere Conclusions and Recommendations Subsurface geologic conditions in the Baynes Lake area are variable and it may not be possible to complete adequate wells on all parcels of land Topographically lower areas adjacent to existing lakes and depressions where underlain by fluvioglacial sands and gravel-provide the best prospects for obtaining adequate supplies from shallow wells Elsewhere, thin sand and gravel layers underlying glacial till or silt may provide limited quantities of water to deeper wells Available precipitation data suggests that groundwater levels in the Baynes Lake area should have been rising since 1980 Causes of local groundwater declines could be explained for example by: 1 Pumping interference of producing wells 2 Changes in land use which restrict recharge 3 Drainage of recharge areas 4 Reduction in well capacities due to inadequate construction The hydraulic relationship between the shallow gravel aquifer underlying the Baynes Lake area and similar deposits extending as far as the Elk0 Dam is presently unknown and would require investigation 4

4 - 4 - AP Kohut August 30, 1985 A monitoring program is required to determine the extent of any water level lowering in the Baynes Lake area This would require establishment of an observation well to monitor seasonal and long-term water level fluctuations A staff gauge should be established on Baynes Lake to monitor lake levels Operational records for the Elk0 Dam should be reviewed particularly with regards to reservoir levels during the period Prior to implementing a monitoring program a field visit should be carried out to confirm geologic conditions in this area and interview residents affected by lower water levels If an existing private well is not available for monitoring purposes it would be necessary to drill an observation well Costs for drilling and constructing an observation well would amount to about $5,000 excluding engineering supervisory costs J Kwong Geo logi Ea1 Engineer Groundwater Sect ion Water Management Branch JK/dma

5 i References i Environment Canada, 1982 Canadian Climate Normals, Temperature and Precipitation British Columbia Atmospheric Environment Service, Environment Canada, p 84 Environment Canada 1985 Monthly Record - Meteorological Observations in Canada ( ) Atmospheric Einvironment Service, Environment Canada Freeze, RA and Cherry, JA 1979 Groimdwater Prentice-Hall, Inc, pp Johanson, D 1976 Groundwater Investigation - Baynes Lake Water Management Branch Memorandum Report, Ministry of Environment Kelley, CC and Sprout, PN 1956 Soil Survey of the Upper Kootenay and Elk River Valley Report No 5 of the BC Soil Survey, BC Department of Agriculture and Canada Department of Agriculture Kohut, AP 1976 Groundwater Investigation - Baynes Lake Water Management Branch Memorandum Report, Ministry of Environment Kohut, AP, Zubel, M, and Choy, HH 1082 Utilization of Cumulative Precipitation Departure Trends in Assessing Long-Term Water Level Fluctuations in Shallow Aquifers in British Columbia Proceedings of Second National Hydrological Conference, International Association of Hydrologists, Canadian National Chapter Ministry of Environment 1985 BC Snow Survey - Annual Summary ( ) Water Management Branch, Province of British Columbia Ryder, JM 1981 Biophysical Resources of the East Kootenay Area: Terrain APD Bulletin 7, Terrestrial Studies Branch, BC Ministry of Environment

6 FIGURES

7 LOCATION MAP i I

8 Topographic B Soil Map Legend Scale 1 : 63,360 (fdy #+%LEY F--Flagstone Sandy Loam W--Wycliffe Silt Loam, isp*-rpsl) r~ h? - 7: b--rouqh broken m--roll ing moranic

9 Y28 - CEMND e Confined aquifer + Drilled well dry (7 Flow rate in gpm 97 Water level in feet (BGL) Scale 1 : 21,000 (approx) Fig 3

10 PRECIPITATION ST/ 11532S2 "I - 1 e' I I I I CUMULATIVE Pi?ECIPITATIOt4 DEPARTURE GRAPH SM NSJZPL awurcr I I,," Fig 4

11 i, TABLES

12 , 7&/e 1 - S W R Y OF WELL LOG INFORMATION - BAYNES LAKE AREA I WELL NO Id& OWNER LOCATION SIZE OEPTH bt I I I I I SUI Q WELL LITHOLOGY CHEMISTRY USES TYPE i / 9Pfl r REMARKS I " -2 e Il I e

13 7aCh f - SWRY OF YELL LOG INFORPIATION YELL NO OWNER LOCATION SIZE DEPTH SWL 2-%- y-a/d :, -, d ;' I BAYNES LAKE AREA YELL LITHOLOGY I CHEMISTRY I USES I REMARKS e--- I I I // I lj4' I t/ 120' /P ' 2/ ' /4 I '7 25 ' 3

14 G6/cI - SUPWRY OF HELL LOG INFORMATION - BAYNES LAKE AREA USES J-, 970

15 -1

16 7ASLf 2 - WATER EOUIVALENT FOR SNOW COURSE IN COLUMBIA BASIN (EAST KOOTENAY) 1984 SNOW W mm (MAY 1) E MEAN mm 207 DEV hrrn SNOGl W E mr, MAY / ) DEV nm -235 SNOW \/E mn, 538 DEV mr, ( 33 yr WCOI I, 74 / U /I I' 1982 _ _ I/ /os 676 /I r / - /op L7P ' I v --I-