Aquifers of the Capital Regional District by Sylvia Kenny University of Victoria, School of Earth & Ocean Sciences Co-op British Columbia Ministry of Water, Land and Air Protection Prepared for the Capital Regional District, Victoria, B.C. December 2004 Library and Archives Canada Cataloguing in Publication Data Kenny, Sylvia. Aquifers of the Capital Regional District. Cover title. Also available on the Internet. Includes bibliographical references: p. ISBN 0-7726-52651 1. Aquifers - British Columbia - Capital. 2. Groundwater - British Columbia - Capital. I. British Columbia. Ministry of Water, Land and Air Protection. II. University of Victoria (B.C.). School of Earth and Ocean Sciences. III. Capital (B.C.) IV. Title. TD227.B7K46 2004 333.91’04’0971128 C2004-960175-X Executive summary This project focussed on the delineation and classification of developed aquifers within the Capital Regional District of British Columbia (CRD). The goal was to identify and map water-bearing unconsolidated and bedrock aquifers in the region, and to classify the mapped aquifers according to the methodology outlined in the B.C. Aquifer Classification System (Kreye and Wei, 1994). The project began in summer 2003 with the mapping and classification of aquifers in Sooke, and on the Saanich Peninsula. Aquifers in the remaining portion of the CRD including Victoria, Oak Bay, Esquimalt, View Royal, District of Highlands, the Western Communities, Metchosin and Port Renfrew were mapped and classified in summer 2004. The presence of unconsolidated deposits within the CRD is attributed to glacial activity within the region over the last 20,000 years. Glacial and glaciofluvial modification of the landscape has resulted in the presence of significant water bearing deposits, formed from the sands and gravels of Capilano Sediments, Quadra and Cowichan Head Formations. Delineated aquifers also included units comprised of sedimentary, intrusive or extrusive igneous, and metamorphic bedrock. A total of sixteen unconsolidated aquifers and eight bedrock aquifers were identified in this study area (24 aquifers in total). These aquifers ranged in size from < 1 km2 to 538 km2. The majority of aquifers are small (<5 km2) to moderate (5-25km2) in size, with the exception of the bedrock aquifers. Unconsolidated sand and gravel, and bedrock aquifers are important water sources in local areas of the CRD. The largest unconsolidated aquifer in the CRD (aquifer 685) is found at Port Renfrew near the western margin of the study area and is the main water source for the community of Port Renfrew and residents of Pacheedaht band on the Gordon River Indian Reserve. Sand and gravel aquifers at Bazan Bay, Hagan Creek, Keating, West Saanich Road and Cordova Bay, on the Saanich Peninsula are thought to be used largely for commercial and irrigation supplies, but may provide domestic water supplies in areas where connection to the municipal distribution system is not available. There is thought to be a greater reliance upon wells for domestic water sources in Sooke, Metchosin, and the Western Communities. Significant unconsolidated aquifers in these areas included aquifer 682 and 683 made up of sand and gravel of the Colwood Delta and Parry Bay formations, as well as aquifers comprised of glaciofluvial and glaciolacustrine sediments in the Sooke River, Young Lake and Mackenzie Lake areas. Also in Sooke and Metchosin is found the largest aquifer in the study area (aquifer 606) a volcanic/igneous bedrock aquifer; this volcanic bedrock aquifer typically has a very low yield. Domestic water supplies in the District of Highlands are almost entirely obtained from water wells in aquifer 680, made up of metamorphic bedrock, which extends over much of greater Victoria. The majority of aquifers were classified as having a low or moderate level of development, largely due to the availability of municipally supplied surface water that is expected to reduce groundwater demand in most locations. Demand for groundwater in the CRD may increase in the future with population growth and continued restrictions on water use in the dry summer months. Nine aquifers were classified as having a low vulnerability, ten aquifers are considered moderately vulnerable, and five aquifers have a high vulnerability. Surficial deposits of clay and till provide confinement for many of the aquifers in the study area, in particular at elevations below 80 m. The partial erosion of these confining sediments resulted in the classification of many of the identified aquifers as moderately vulnerable to contamination associated with pollutants introduced at the land surface. Bedrock aquifers Aquifers of the CRD Page i more often encompass land occurring on high elevation ridges and peaks. Often lacking a surficial layer of clay or till, these bedrock aquifers are generally considered more vulnerable to contamination. The productivity of aquifers within the CRD generally ranges from low to moderate; only two highly productive aquifers were identified, both associated with sedimentary deposits in major river drainages, such as aquifer 684 at the mouth of the Goldstream River and aquifer 685 along the San Juan River floodplain. Isolated water quality concerns were identified in six aquifers. Identified concerns related to human health included isolated occurrences of bacterial contamination, localized hydrocarbon contamination from underground storage tanks, and high concentrations of nitrate (the latter parameter within the Guidelines for Canadian Drinking Water Quality). Additionally, elevated concentrations of arsenic exceeding the Guidelines for Canadian Drinking Water Quality were reported for one aquifer. Isolated concerns related to the aesthetic potability of water included elevated concentrations of iron and manganese, and intrusion of saline waters in coastal areas. Isolated concerns related to water quantity were identified in eight aquifers, mainly related to well interference, seasonal low yields or dry wells. Since the initial phase of the aquifer mapping and classification project in 2003, the locations of wells and aquifers in the Capital Region have been added to the data set included on the CRD Natural Areas Atlas online mapping resource. Following the completion of the inventory of aquifers in the study area, the following steps should be considered by the CRD: 1. Present the project results to representatives of the CRD, municipalities, local stewardship groups and stakeholders; 2. Include display themes for all mapped and classified aquifers in the CRD Natural Areas Atlas online resource; 3. Consider exploring ways to promote local well stewardship and to educate well owners about water conservation practices, regular testing of the quality of their well water, and proper well maintenance, operation and abandonment. This may be done in partnership with MWLAP or the local health unit. Aquifers of the CRD Page ii Acknowledgements The success of any project hinges upon the successful collaboration between numerous individuals at each phase, from conception through to implementation and completion. This project is particularly indebted to Mike Wei, of the B.C. Ministry of Water, Land and Air Protection (MWLAP) Water Protection Section, who was instrumental in initiating this Regional–Provincial government partnership, and provided in–depth training, professional review, and encouragement to the author throughout the project. Mary Anne Fillipone and Michael Williams of the Capital Regional District (CRD) Environmental Services Department, and Jack Hull of the CRD Water Department are gratefully acknowledged for their support and involvement in the development and implementation of this project, including establishing project funding, providing direction on key objectives and providing feedback on the completed work. Thanks also go to Kevin Ronneseth (MWLAP, Water Protection Section), who provided training, supervision, and technical feedback. The author also benefited from a wealth of information on the study area, obtained from internal reports by past and present staff of the Ministry of Water, Land and Air Protection. Rick Hardy of Land and Water B.C. digitized the aquifer polygons and provided valued advice on technical aspects of the mapping process. Staff of municipal government agencies assisted in provided information on the drinking water infrastructure within the study area, needed to gauge areas of groundwater use for drinking water, and the relative dependence on the groundwater resource. These individuals include Doug Leslie of the City of Victoria Engineering Department, Corey Paiement and Jas Paul of the District of Saanich Planning Department, Tim Tanton from the Town of Sidney Engineering Department, Julie Rivet of the District of North Saanich Engineering Department, Mike Van der Linden of the District of Central Saanich Engineering Department, Bruce Woodbury of the District of Highlands, David Reay of the City of Colwood Engineering Department, and Dave Newman from City of Langford Engineering. Gary Hendren from CRD Evironmental Services, Rodney Thur administrator with the Pacheedaht Band and Mike Pichichero of Health Canada conveyed information on wells in the Port Renfrew area. Mary Steele and Misty McDuffy of Peninsula Streams were similarly helpful in providing reference materials on Central Saanich. Stefanie Blouin and Bruce Chambers of the Department of National Defence and Rachael McIlroy of Royal Roads University provided numerous hydrological reports on Royal Roads and Esquimalt