Information submitted on behalf of Sylvia Kenny, Ministry of Environment Groundwater Protection Officer
Aquifers – identification, mapping and composition:
The mapping of aquifers on Quadra Island was completed in 2005 by hydrogeologist, Bill Hodge, on contract to the Ministry of Environment. The locations and boundaries of aquifers are determined from a number of different sources of information. These sources include: the known locations of natural water divides, such as watershed boundaries; the spatial extent of the different geologic units such as major sand and gravel deposits, as determined from air photos or existing maps; and upon the area of development where successful wells have been drilled in the different sediment or rock types.
On an aquifer classification map, the symbol used to represent the boundaries of the aquifer indicates the level of surety that the boundary is at that location. For example, a solid line indicates a high level of surety, a dotted line indicates a lower level of surety that the boundary has been placed in the right location. The aquifer boundaries can change when new information becomes available, such as from looking at the construction records for new wells. The mapping and classification of aquifers is a tool for educating the public about where aquifers are, and to help guide and prioritize monitoring and resource management programs, for example toward aquifers that are moderately to highly developed (with a larger number of users) and moderately to highly vulnerable to contamination.

There are two general types of aquifers - those made up of sand and gravel, in which water is stored within the pore spaced between the sand or gravel particles, and bedrock aquifers in which water is stored within individual fractures in the rock. Wells that are constructed in unconsolidated aquifers can often produce more water than wells in bedrock aquifers. Within bedrock aquifers that are made of limestone, fractures and passageways in the rock can be enlarged when the rock is dissolved by water, therefore these types of aquifers can have sometimes yield higher water quantities to wells and springs.


Aquifers are also sometimes described based on the materials that overly them, which influences how vulnerable they are to contamination. Fine grained sediments such as clay slow the rate of movement of water and potential contaminants into the sub-surface. Additionally, if fine clays or silts are present, the water move slowly through these sediments and some pollutants may be naturally filtered out in the process. Within an unconfined aquifer, the upper boundary of the aquifer is the water table, and little to no confining sediments are present. These types of aquifers are generally more vulnerable to contamination. An aquifer that has an overlying layer of clay or compact till is referred to as confined, and is thought to have a lower level of vulnerability to contamination. Bedrock aquifers are often developed in areas where the surface sediments including clay are thin or absent, therefore they generally can be more vulnerable to contamination. The locations of wells and mapped aquifers on Quadra Island can be found on the B.C. Water Resources Atlas at http://srmapps.gov.bc.ca/apps/wrbc/.

Surface Water and its Storage:
Surface water bodies are replenished directly by rainfall or snowfall, and indirectly by the discharge of groundwater back to the surface. How long water is stored within a surface water body naturally (without the aid of weirs or dams) depends upon factors such as the total drainage area, the storage volume of the water basin or channel, how much water is flowing through the system, the topographic relief or maximum and minimum elevation of the water basin and many other factors. Water as a rule makes its way from high to low elevation as part of the water cycle. For some lakes or rivers the residence time of water is very short (less than a year), whereas within other surface water bodies e.g. the Great Lakes, water is stored for a much longer period.
It is possible to enhance storage or create artificial storage, for example by diverting water to a dug out or pond during winter periods to use during the summer, or by constructing weirs or dams to increase the storage capacity of a reservoir, such has been done in many large watersheds in B.C. Any type of diversion or work in and about a surface stream requires an approval and/or licence issued through the Ministry of Environment, Water Stewardship Division.
Rainfall can also be stored in cisterns from rooftop collection systems to offset water obtained from streams or wells. Within the Quathiaski Cove area it is my understanding that water for drinking and other uses comes from a range of different sources--individuals who have property on which there is a creek or stream may be able to use surface water, while other facilities or households obtain water from individual domestic wells or shared community wells or water supply systems.
Another problem on the islands is the seasonal availability of water. If we compare the amount of rain we get with the amount of water we need over a year period, there should be enough, but we typically use more water in the summer period, when there is very little water being added to the aquifers, rivers and lakes. Therefore enhancing opportunities for storage, such a using cisterns, can help the community through dry summer periods.


Salt Water Intrusion:
Ocean water has a high density because of its salinity, which is produced by a high concentration of dissolved minerals, including sodium. Within an island setting, below the water table there is a lens of low density fresh water that overlies saline oceanic water with a higher density. Between the two water types there is zone of mixing or interface where the water is brackish, or has moderate or lower salinity compared to pure sea water. Over pumping of wells close to the sea within a coastal aquifer can change the location of the salt-fresh water interface, drawing salt water to shallower depths or drawing it inland.


Groundwater Protection & Vancouver Island Water Resource Vulnerability Mapping Project:

Groundwater sources can be protected in a number of ways:
• Protecting the well itself with good siting, construction and maintenance practices;
• Protecting the capture zone that contributes water to a well; and
• Protecting the aquifer as a whole, by understanding how vulnerable different parts of the aquifer are, and the risks associated with different land use activities.
The B.C. Ground Water Protection Regulation protects individual wells by establishing minimum qualifications and registration for people involved in the well drilling and well pump installation industry, and setting standards for well construction, testing, maintenance, alteration and closure.
The Well Protection Tool Kit, available for free on the Internet from the Ministry of Environment, is a six-step process to map the capture zone for a well, and to assist communities with making plans to protect a well by managing risk activities in the capture zone. A well head protection plan can be prepared for important wells, such as those that supply water to a community system or a large population of users.
On the broadest scale, Natural Resources Canada, the Vancouver Island Health Authority, the Regional Districts of Nanaimo and Cowichan Valley, Malaspina University-College and Ministry of Environment are working together on the Vancouver Island Water Resource Vulnerability Mapping Project. Over the next 3 to 5 years the study is going to identify and map the vulnerability of aquifers in the Vancouver Island Region (including the islands), based on the characteristics of the different aquifers, and to combine this with an assessment of risks associated with different land use activities. The resulting maps can then be used by planners, local government and other decision makers to manage land uses and reduce the risk of aquifer contamination and to help ensure groundwater resources are protected for future generations. Some preliminary mapping for this project has been completed for the southern Gulf Islands, including Salt Spring, Pender, Saturna, Galiano, Mayne and Pender Islands. Typically the first step of this mapping and assessment process has been the compilation of information from wells in different areas.