LONG-TERM MONITORING OF GROUNDWATER CONDITIONS IN

FRACTURED BEDROCK AQUIFERS ON VANCOUVER ISLAND AND THE

GULF ISLANDS, BRITISH COLUMBIA Pat Lapcevic, British Columbia Ministry of Environment, Nanaimo, B.C. Sylvia Kenny, British Columbia Ministry of Environment, Nanaimo, B.C. Mike Wei, British Columbia Ministry of Environment, Victoria, B.C. ABSTRACT Groundwater provides potable water to thousands of residents on Vancouver Island and the Gulf Islands. On most of the Gulf Islands and parts of the east coast of Vancouver Island, the Nanaimo Group of sandstone, conglomerate and shale formations serve as a primary source of water. These aquifers tend to exhibit fracture-controlled flow, are unconfined, rapidly recharged, and vulnerable to contamination due to thin layers of overburden. On Vancouver Island, in addition to the aforementioned sedimentary aquifers and unconsolidated deposits, deeper metamorphic and igneous rock aquifers are being used as groundwater sources. The “BC Aquifer Classification System” maps and classifies developed aquifers based on the level of development and vulnerability to contamination. This provides a framework to target groundwater monitoring activities in higher priority aquifers. Currently, 176 aquifers have been classified on Vancouver Island and the Gulf Islands. A network of 68 dedicated observation wells, some in existence for over 50 years, provide a measure of both the quality and quantity of groundwater resources over time in the region. This paper examines trends in long-term groundwater-levels in three typical fractured rock aquifers in the region. Continued development, population growth and climate change in the decades to come is expected to place added pressure upon groundwater resources in this region. In addition to classifying and characterizing aquifers, long-term temporal measurements obtained from dedicated observation wells is important to provide decision makers with the appropriate technical data to ensure that our groundwater resources are protected and managed in a sustainable manner for future generations.

RÉSUMÉ Les eaux souterraines fournissent l'eau potable aux milliers de résidants sur l'île de Vancouver et les îles de Golfe. Sur la plupart des îles de Golfe les roches de la formation Nanaimo (grès, conglomérat et shale) servent comme source primaire de l'eau. Ces couches aquifères sont contrôlés par les éléments structuraux, sont non-confiné, rapidement rechargé, et vulnérable à la contamination dans les secteurs où le matériel au-dessus de la couche aquifère est mince. Sur l'île de Vancouver, en plus des couches aquifères sédimentaires mentionnées ci-dessus, couches aquifères plus profond de roches métamorphique et plutonique sont employées comme sources d'eaux souterraines. La qualité et la quantité de l'eau extraites de ces couches aquifères est variable. Le système de classification de couche aquifère pour la province de Colombie-Britanique trace et classifie les couches aquifères basées sur le niveau du développement et la vulnérabilité à la contamination. Ceci fournit un cadre pour identifier des activités de surveillance en couches aquifères prioritaires. Actuellement, 176 couches aquifères ont été classifiées sur l'île de Vancouver et les îles de Golfe. Un réseau de 68 puits d'observation, certains en existence pendant plus de 50 années, fournissent une mesure de la qualité et de la quantité de ressources d'eaux souterraines dans la région. Spécifiquement, cette étude se concentre sur trois couches aquifères de roche en place qui sont représentant de la région. Les facteurs tels que le développement, la croissance de population et le changement de climat ont le potentiel de réduire la capacité de ces ressources. En plus de classifier et de caractériser des couches aquifères, il est important que les mesures de puits d'observation à long terme fournissent l'information suffisante à des décideurs pour protéger et contrôler ces ressources pour l'avenir.

1. INTRODUCTION

Thousands of residents of Vancouver Island and the Gulf Islands in southwestern British Columbia, Canada depend on groundwater as their primary source of potable water. On the Gulf Islands surface-water is generally limited and both full-time and summer residents

rely on the groundwater resources of the Upper Cretaceous Nanaimo Group of sandstone, conglomerate and shale formations as a primary source of water. On Vancouver Island, in addition to aforementioned fractured sedimentary rock aquifers, unconfined and confined sand and gravel fluvial and glaciofluvial surficial deposits form aquifers that are productive and are easily exploited. In

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some areas of Vancouver Island, deeper metamorphic and igneous rock aquifers of sometimes marginal quality are being used as groundwater sources. Continued development, population growth and climate change in the decades to come is expected to place added pressure upon finite groundwater resources in this region particularly on the East side of Vancouver Island and some of the larger more accessible Gulf Islands. In addition to classifying and characterizing aquifers, long-term temporal measurements obtained from dedicated observation wells are important to ensure that decision makers have appropriate technical data to ensure protect and manage groundwater resources in a sustainable manner for future generations. In this paper we summarize the nature of the developed aquifers on Vancouver Island and examine specifically at long-term trends in water level measured in observation wells in three fractured bedrock aquifers in the region (Figure 1). 2. HYDROGEOLOGY 2.1 Vancouver Island Vancouver Island is part of the Insular Belt, the westernmost of five northwesterly trending subdivisions of the Canadian Cordillera. The island is, at its core, a piece of crust known as Wrangellia. Three major periods of volcanism separated by episodes of sediment accumulation led to the formation of the Island in its current form. The bedrock geology of the island is dominated from oldest to youngest by: (1) The Paleozoic Sicker and Buttle Lake Volcanics, (2) The Late Triassic Karmutsen volcanic rocks and Quatsino limestone, (3) Bonanza volcanic rocks, (4) Island and Westcoast intrusive rocks, (5) Nanaimo Group Sedimentary formations and (6) Tertiary rocks (i.e. Metchosin Volcanics, Leech River gneisses and others). At least three periods of glaciation have also affected the geology of Vancouver Island. The effects related to the Fraser glaciation of Late Wisconsian Age (ending about 10,000 years ago) are widespread and include thick deposits of glacial sand and gravel (Yorath, 2005). The most productive aquifers in this region are thick glacial and glaciofluvial deposits which are often associated with river valleys. On the southeast side of Vancouver Island aquifers associated with the Cowichan, Chemanius, and Qualicum Rivers are examples of highly productive river aquifers comprised of sand and gravel. In the north and western portions of Vancouver Island isolated communities use groundwater from glacial aquifers as a reliable source of potable water (e.g. Kyuquot, Port Alice, and Malcolm Island). Bedrock aquifers on Vancouver Island include the Nanaimo Group sandstones, conglomerates and siltstones (discussed further in the next section) as well as volcanic and granitic rocks from the Island intrusive rocks, Karmutson Formation and Teritiary rocks. These rocks are generally

of low porosity and groundwater potential is dependent on the presence of open fracture zones and joints. Examples of volcanic and granitic fractured bedrock aquifers are described in Kohut (2004) and Kenny (2004). 2.2 Gulf Islands The Gulf Islands are a series of islands located within the Georgia Strait separating Vancouver Island from the Canadian mainland (Figure 1). Bedrock on the islands is predominantly sedimentary rock of the Upper Cretaceous Nanaimo Group. The Nanaimo Group is interpreted as primarily a marine sedimentary sequence up to 4 km thick of conformable and intertonguing successions of sandstone and conglomerate separated by mudstone and siltstone (Mustard, 1994). Mackie (2002) using detailed fracture mapping on the main southern Gulf Islands, suggested that the bedrock on the Gulf Islands could be subdivided into lithologic-based (sandstone-dominant lithologies and mudstone-dominant lithologies) and structure-based (fault and fracture zones and discrete faults and fractures) hydrostructural domains. While highly variable, fracture intensity (and therefore resulting permeability) is thought to be greater in mudstone-dominant lithologies versus sandstone-dominant lithologies. Applying fracture models to Saturna and Mayne Islands indicated moderate to good correlation between hydrostructural domains and the distribution of relatively high yielding wells (Mackie, 2002). Bedrock aquifers on Vancouver Island and the Gulf Islands generally exhibit complex hydraulic response to pumping with linear flow often observed (Abbey and Allen, 2000 and Allen, 2002). Linear flow behaviour is indicative of the presence of vertical fractures and joints controlling the flow system.

Figure 1. Location of study sites.

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3. AQUIFER CLASSIFICATIONS

The “BC Aquifer Classification System” maps and classifies developed aquifers based on the level of development and vulnerability to contamination (Berardinucci and Ronneseth, 2002). This classification system provides a framework to target characterization and monitoring activities in higher priority aquifers. The system has two components: (1) a classification component and (2) a ranking component. The classification component categorizes aquifers into one of nine categories based on their current level of groundwater development and vulnerability to contamination (Table 1). The level of development considers both the productivity of the aquifer and degree of use. The ranking component assigns a numerical point value to each aquifer based on seven criteria including productivity, vulnerablility, size, water demand, type of use, and identified concerns related to groundwater quality or quantity (Berardinucci and Ronneseth, 2002). Aquifers have generally been delineated based on data from well construction reports, geological and structural mapping and hydrogeological study reports.

Table 1. Aquifer classification matrix illustrating nine categories.

I II III

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IA – heavily developed, high vulnerability aquifer

IIA – moderately developed, high vulnerability aquifer

IIIA – lightly developed, high vulnerability aquifer

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IB – heavily developed, moderate vulnerability aquifer

IIB – moderately developed, moderate vulnerability aquifer

IIIB – lightly developed, moderate vulnerability aquifer

C

IC – heavily developed, low vulnerability aquifer

IIC – moderately developed, low vulnerability aquifer

IIIC – lightly developed, low vulnerability aquifer

Currently, 176 aquifers have been classified on both Vancouver Island and the Gulf Islands. About 51 % of these aquifers are considered most vulnerable to contamination or unsustainable development (IA, IIA, IB and IIB) (Figure 2). Forty-eight percent of the classified aquifers have ranking values of 10 or greater (maximum possible value is 21). The classified aquifers are generally located in the developed eastern side of Vancouver Island and the Gulf Islands. Bedrock aquifers account for 51% of the aquifers classified and 66% of these aquifers are considered most vulnerable to contamination or unsustainable development. The bedrock aquifers range in area from 0.06 km2 to 305 km2. Detailed reports on the some of the mapped aquifers in the region can be found in Humphrey (2000), Kenny (2004) and Kohut (2004).

Information and maps of the classified aquifers can be found through “The BC Water Resources Atlas” at http://srmapps.gov.bc.ca/apps/wrbc/. In this study, we focus on monitoring results in three of these fractured rock aquifers (Figure 1). The first is the North-Central Saanich aquifer (Aquifer 608) which is comprised of fractured granodiorite of the Island Plutonic Suite and extends over 81 km2 on the Saanich peninsula North of Victoria on Vancouver Island (Kenny, 2004). This aquifer has been classified as IIB (moderately developed, moderate vulnerability). The second aquifer studied is located on the South End of Gabriola Island (Aquifer 709). The aquifer extends 46.8 km2 and has been classified as IIA (moderately developed, high vulnerability). It is comprised of sandstone with minor shale and conglomerate rocks of the Gabriola, Geoffrey, Spray and Northumberland Formations of the Nanaimo Group sediments. Surficial deposits on Gabriola Island range from non-existent to a maximum of about 15 m. Hence the aquifer is largely unconfined to partially-confined with isolated confined areas as evident through the presence of artesian wells. Regional groundwater flow is expected to be from higher elevations in the centre of the island to discharge into the ocean.

The third aquifer is also comprised of Nanaimo Group sediments and is located on Galiano Island (Aquifer 320). It is 58 km2 in area and has been classified as IIB (moderately developed, moderate vulnerability). This bedrock aquifer encompasses the entire island and is developed primarily in coastal areas. Both of the Nanaimo group aquifers are typical of conditions in other similar aquifers on the Gulf Islands and southeast coast of Vancouver Island.

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4. OBSERVATION WELL NETWORK

Since 1961, the British Columbia Ministry of Environment has operated a network of observation wells throughout the province. The current network of dedicated observation wells in the Vancouver Island Region totals 68 wells. The length of available record ranges from 40 years to less than 6 months. Thirty-six of these wells are completed in bedrock aquifers while the remainder of the wells are completed in surficial (sand and gravel) aquifers. Water level measurements over time have been obtained from the wells using one of several methods (1) manually with a wetted tape, (2) continuously using Steven's chart recorders, or (3) electronically with data loggers. Since 2003, ThalimedesTM instrumentation consisting of a float-operated shaft encoder and electronic data logger are used in most wells in the region to obtain measurements at a rate of one per hour (the average of four fifteen minute readings is stored) (Kohut, 2005). The data presented in this paper is a combination of “month-end readings” obtained through monthly manual measurements or extracted from the chart recordings and continuous data logger measurements. Hydrographs are presented as water level in metres below ground surface (mbgs) versus time. Groundwater samples are obtained by pumping from each well approximately once every three years during the dry period (late summer to early fall). Overall, the network provides a measure of both the quality and quantity of groundwater resources over time in a number of different types of aquifers in the region. Taylor and Alley (2001) present a good overview of long-term monitoring of groundwater levels. At present, over 90% of the active observation wells are located in 33 of the classified aquifers. Bedrock observation wells are used to monitor conditions in 18 of the classified aquifers. The bedrock aquifers being monitored are for the most part located in high priority aquifers (IA, IIA, IB and IIB) with only one monitor in an IIIB aquifer. Daily total precipitation data was obtained for three stations (Victoria Airport, Galiano North and Gabriola Island) from “The National Climate Data and Information Archive” (Environment Canada, 2006).

5. LONG-TERM TRENDS IN WATER LEVELS 5.1 Site 1 – North-Central Saanich Aquifer Eight active monitoring wells are completed in a fractured granodiorite aquifer on the Saanich peninsula just north of Victoria on Vancouver Island (Figure 3). In this study we examine the water level hydrographs for six of these wells (the characteristics of the wells are summarized in Table 2). Based on their hydrograph response and location on the peninsula, three wells can be broadly classified as being located in discharge areas while the other three are in recharge areas (Table 2). The recharge area wells in

Figure 3. Location of Site 1, Saanich Peninsula range in depth from 41 m to 154 m in depth and intersect 1 m to 14 m of glacial sediments which overly the bedrock. The discharge area wells range in depth from 30 m to 152 m and have 0 m to 10 m surficial material overlying the rock. While all six wells show a response to fall precipitation and the lack of precipitation in the summer months, there are distinct similarities within each group and differences between the two groups of wells (Figure 4). Well 65 shows annual variations in water level between 1.5-2.5 m (Figure 4). Its annual minimum water level usually occurs between October to December and maximum level between February and April. The bedrock at this well is confined by 14 m of glacial sediments. This well illustrates a classical recharge area well and appears to be measuring ambient conditions and is not affected by local pumping. Well 212 also in a recharge area shows annual variations ranging from approximately 7 m to 30 m with the largest changes occurring between 1988 and 1996 (Figure 4). After 1996, local usage likely changes (possibly the change from single domestic wells to municipal water servicing) which is reflected by higher minimum levels. This well usually starts to recover a few weeks prior to Well 65 in the fall. The earlier recovery may be due to a reduced lag time (surficial sediments are 6 m at this site) or possibly a cessation of seasonal

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pumping in addition to response to precipitation. This well shows the influence of aquifer pumping in other wells. However, annual maximum levels generally recover to approximately the same level annually. Well 343 is located further to the south on the peninsula on the flanks of Mt. Newton, a prominent topographic high. Annual water level variation in this well ranges from 12.5 to 14.5 m. This well intersects 1 m of overburden. The hydrograph suggests that the well is measuring ambient conditions and not influenced by nearby pumping. The three wells loosely classified as discharge wells (240, 265, 333) show annual variations in water level between 5 m and 10 m. Water levels measured in Well 265 indicate an approximately 2 m decrease in maximum water levels and about 5 m decrease in minimum water levels over the last 20-25 years. Similar trends are seen in the hydrograph for Well 333. Both of these wells are likely influenced by pumping in the aquifer. The wells in the discharge area show an earlier initial annual rise in water level in response to fall and winter precipitation than those in the recharge areas. For example the difference in 2001 is approximately 4 months (Well 333 starts to rise in August while Well 343 starts to rise in November) (Figure 5). This difference may reflect hydrograph response to a cessation of seasonal pumping and not solely due to response to precipitation. It was noted above that wells 333 and 265 are in developed areas and exhibit increased decreases in the receding limb of the hydrograph. A long-term cyclicity is observed in Well 65 and possibly Well 240. In Well 65 levels are increasing between 1977 and 1981 then decrease to 1992 and rise again to 1997. These changes are probably reflective of longer-term climatic changes and should be investigated further. Table 2. Summary of characteristics of observation wells in granitic aquifer in Saanich.

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Start of Record

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Seasonal Variation in Water Level

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65 154 14 1972 Recharge 1.5-2.5 212 41 6 1977 Recharge 5-30 343 152 1 1999 Recharge 12.5-14.5 240 153 9 1979 Discharge 5-6 265 30 8 1980 Discharge 5-10 333 61 0 1997 Discharge 7-10

Previous analyses of water levels in this aquifer and the Nanaimo Group sedimentary aquifers discussed in the next section (Kohut et al., 1984) observed that generally the wells in recharge areas responded earlier than those in discharge areas. In a classical groundwater flow system where

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groundwater flow systems are recharged primarily in “high elevation zones” one would expect recharge areas to respond to water input from precipitation prior to discharge areas. The reverse trend that we observe in this aquifer may indicate that the discharge areas in this aquifer are influenced by other sources of water such as direct local infiltration possibly through a vertical fracture or are responding to other factors such as the cessation of pumping. This has implications from a groundwater protection/management perspective in understanding where water inputs into the system. In other words, protecting only “high elevation” areas for groundwater recharge and allowing development in “discharge areas” may limit total recharge to the system. Overall we note that the maximum water level in the aquifer appears to not be affected by changes in total precipitation. This is not surprising as the limiting factor in the system is not precipitation (average annual precipitation measured between 1971 and 2000 at the Victoria International Airport was 883.3 mm (Environment Canada, 2006)) but instead is the low storage capacity of the fractured rock systems. The granodiorite has a low primary porosity and hence the aquifer is controlled by fractures and faults.

Figure 6. Location of Site 2, Gabriola Island.

5.2 Site 2 – Gabriola Island On Gabriola Island two of five currently active observation wells have been monitored for over 30 years. The hydrographs for these two wells are shown in Figure 7. Well 194 is 76 m in depth and intersects about 0.6 m of overburden. It is located in the developed village area of the island where numerous wells are used by single family homes, businesses, an elementary school and offices. Overall the water level fluctuates by approximately 2 m seasonally with highs around 18 m below ground surface and lows about 20 m below ground surface. Between 2002 and 2004 the measured minimum water level appear to have increased. The receding portion of the annual hydrograph has a distinct concave shape suggesting that in addition to seasonal influences the hydrograph is exhibiting changes to increased use during the dry period. The maximum annual water level attained during the winter period remains constant indicating that the aquifer is obtaining sufficient recharge and is not being depleted. The upper hydrograph in Figure 7 is of Well 197. This well is 83 m deep and intersects about 1.2 m of surficial deposits and is located on undeveloped property. A similar seasonal cycle of increasing fall and winter levels followed by decreases in the spring and summer seasons is observed and annual variation is about 2.5 m. Generally, the receding limb of the annual cycle follows an exponential curve suggesting a system not influenced by withdrawals. Well 197 appears to be showing a long-term cyclicity in the water-levels noted by increases beginning in about 1988. This may be due to longer-term climatic cycles and should be examined further. Both of these observation wells are located in areas of higher elevation however groundwater flow in the vicinity of the village likely flows northwest to the ocean while at Well 197 flow is more northeasterly. Like most bedrock wells in the region both observation wells are open wells below 3 – 6 m of steel casing installed through the overburden and hence the resultant water level is may be representative of one or more distinct fracture zones or flow systems.

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Figure 5. Hydrographs for three wells completed in the Saanich granodiorite aquifer compared to daily total precipitation (measured at Victoria Airport close to well 65).

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Figure 7. Hydrograph of two monitoring wells on Gabriola Island (upper trace corresponds to y-axis on the left and lower trace corresponds to y-axis on the right). 5.3 Site 3 – Galiano Island Galiano Island is a long narrow island with very little surface water resources (Figure 8). Like the majority of the Gulf Islands it relies on groundwater extracted from bedrock wells for most of its potable water supply. Figure 9a shows the variation in water level over about 25 years in a 104 m well completed in sandstone. The water level shows a cyclical pattern similar to that seen on Gabriola Island. Figure 9b shows a detailed hydrograph for the last two and half years. The water level responds quickly (less than a day) to precipitation over about 10 mm. A large precipitation event in late March 2005 does not influence the water level substantially. This illustrates the low storage capacity as being the limiting factor to recharge of the aquifer and not the total amount of precipitation. Allen et al. (2002) reported average measured storativities for the Nanaimo group aquifers from 1 x 10-4 to 7 x 10-4. The annual minimum water level in this observation well has decreased by about 8 m over the monitoring period (Figure 9c). This is probably related to increased use of the aquifer in a developed area with numerous private wells. The maximum water level is not trending downwards and recovers to a similar level each winter, suggesting that the usage to date is sustainable. However, while the total annual output do not seem to be exceeding precipitation inputs, seasonal water availability is a critical issue, particularly for owners of wells with limited available drawdown. Considering the coastal island environment, one must also be cognisant of the potential of causing changes in the fresh-water/salt-water interface through excessive pumping of a coastal aquifer. This observation well is located about 590 m from the island coastline, and likely will not be impacted by salt water intrusion, however wells located in the same aquifer closer to the shore may be affected regardless of the recovery of water level in the winter months.

Figure 8. Location of aquifer 3, Galiano Island.

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6. SUMMARY Maintaining a long-term groundwater monitoring network for decades presents both opportunities and challenges. Dedicated observation wells provide water managers with essential data needed to better understand the conditions and response to stresses in aquifers over the long-term. However, in times of constantly changing resources it is incumbent on us to continuously review our choice of monitoring points and the relevance of each well to the program objectives. The Vancouver Island Network currently monitors groundwater levels and quality in 68 wells primarily on the east side of Vancouver Island and on most of the larger Gulf Islands. Most of the wells are completed in priority aquifers as determined through the BC aquifer classification system. Wells in granitic and sedimentary fractured rock aquifers exhibit similar patterns of annual water level variation. The limiting factor to recharge of the aquifers in both cases is the low storage capacity of the rock system and not the amount of available precipitation. The detailed measurements of water level in this complex fractured rock environment suggests that unlike classical porous media conceptual models of groundwater flow systems with distinct recharge and discharge zones, the presence of significant vertical fractures may dominate the flow systems to cause rapid infiltration in discharge areas. Most of the observation wells indicate that the groundwater resource is being used in a sustainable manner. However, in several areas usage is increasing in times with little to no recharge suggesting that careful consideration should be undertaken to ensure that these trends do not lead to water shortages or irreparable quality changes (particularly salt water intrusion). The long-term groundwater level data discussed in this paper suggests that in addition to protecting the functionality of groundwater recharge areas, managing usage particularly in the dry summer period will be essential to ensuring the viability of groundwater resources in the future. 7. ACKNOWLEDGEMENTS We appreciate the assistance Kevin Ronneseth provided on the aquifer classifications. Shannon Denny generously provided a French translation of the abstract. Brian Epps and Roberta Patterson assisted in the compilation of data from the observation wells. References Abbey, D.G. and Allen, D.M. 2000. Fracture Zones,

Aquifer Testing and Scale Effects: Considerations in Fractured Bedrock Aquifers of Southwestern British Columbia, proceedings of the IAH-CNC conference, Montreal, 2000.

Allen, D.M., Liteanu, E., Bishop, T.W. and Mackie, D.C. 2003. Determining the Hydraulic Properties of Fractured Bedrock Aquifers of the Gulf Islands, BC,

Report prepared for the BC Ministry of Water, Land and Air Protection.

Berardinucci, J. and Ronneseth, K. 2002. Guide to using the B.C. Aquifer Classification Maps for the Protection and Management of Groundwater, Victoria, BC: Ministry of Water, Land and Air Protection.

Environment Canada 2006. The National Climate Data and Information Archive, http://www.climate.weatheroffice.ec.gc.ca/climateData/canada_e.html

Humphrey, G.J., 2000. Regional District of Comox-Strathcona Aquifer Classification Project Report, prepared for Regional District of Comox-Strathcona, 44 pp. (+ Appendices).

Kenny, S., 2004. Aquifers of the Capital Regional District, report prepared for British Columbia Ministry of Water, Land and Air Protection and Capital Regional District, 112 pp. (+ maps).

Kohut, A., Hodge, W.S., Johanson, A., and Kalyn, D. 1984. “Natural seasonal response of groundwater levels in fractured bedrock aquifers of the southern coastal region of British Columbia.” International Groundwater Symposium on Groundwater Resources Utilization and Contaminant Hydrogeology, Montreal, PQ. 1:97-107.

Kohut, A., 2004. Aquifer Classification Mapping of the Alberni Valley Area, British Columbia, report prepared for British Columbia Ministry of Water, Land and Air Protection.

Kohut, A., 2005. Procedure Manual for Groundwater Observation Well Data Acquisition and Validation, report prepared for B.C. Ministry of Water, Land and Air Protection, 44 pp. (+ Appendices).

Mackie, D.C., 2002. An Integrated structural and hydrogeologic investigation of the fracture system in the Upper Cretaceous Nanaimo Group, Southern Gulf Islands, British Columbia, M.Sc. Thesis, Simon Fraser University, Burnaby, B.C.

Mustard, P.S., 1994. The Upper Cretaceous Nanaimo Group, Georgia Basin: in Geology and Geological Hazards of the Vancouver Region, Southwestern British Columbia, (ed.) J.W.H. Monger: Geological Survey of Canada, Bulletin 481, p. 27-95.

Taylor, C.J. and Alley, W.M. 2001. Ground-Water-Level Monitoring and the Importance of Long-Term Water-Level Data, U.S. Geological Survey Circular 1217, 68 pp.

Yorath, C. 2005 The Geology of Southern Vancouver Island. Harbour publishing, Madeira Park, BC. 205 pp.

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