The primary objective of the RDN Water Budget Project was to develop a better understanding of the surface and groundwater flow systems within the RDN. In order to meet the intent of the study, compilation of available information into a comprehensive electronic geodatabase was completed by Waterline.
The electronic information was used to develop conceptual models of the hydrogeology within each of the six water regions within the RDN. This information was needed in order to assess the water movement and exchange between various watershed elements including rivers/creeks, lakes, and groundwater aquifers.
The Phase one water budget assessment was an initial attempt to consider the inputs and outputs from the surface water and groundwater systems using existing data on a water region basis. The geodatabase developed by Waterline was used to construct two and three dimensional hydrological and hydrogeological images in order to visualize and understand how surface features and activities relate to subsurface aquifers.
The compiled data, in conjunction with water use data developed by the RDN, was used to assess the level of stress on each of the six water regions and 28 mapped aquifers across the Vancouver Island area of the RDN.
The following table provides a summary of the results of the conceptual water budget assessments completed as part of the study.
Major watersheds within the RDN exhibiting moderately high to high apparent stress include the following:
- French Creek,
- Nanoose Creek,
- Chase River, and
- the Nanaimo River.
Mapped aquifers exhibiting moderately high to high or very high apparent stress include the following:
- Quadra Sand Aquifer 421 located in WR1 (BQ) adjacent to Nile Creek,
- Haslam Formation Bedrock Aquifer 220 which extends across 3 regions including WR1 (BQ), WR2 (LQ), and WR3 (FC),
- Vashon (Kame) Aquifer 663 at the top of Whisky Creek in WR2 (LQ),
- Quadra Sand Aquifer 217 extending from WR2 (LQ) to WR3 (FC),
- Quadra Sand Aquifer 216 in WR3 (FC) and extending into WR4 (ER),
- Buttle Lake Group Bedrock Aquifer 210 in upper Nanoose Creek,
- Benson Formation bedrock Aquifer 218 located on the Nanoose Peninsula,
- Quadra Sand Aquifer 215 beneath the District of Lantzville,
- Vancouver Group and Nanaimo Group bedrock aquifer 211 located at Benson Meadows,
- Upper Cassidy (Capilano) Aquifer 161,
- Nanaimo Group bedrock Aquifer 162 located in the Cedar-Yellow Point Area, and
- Quadra Sand Aquifer 163 located in an isolated pocket in the Cedar area.
Due to the regional nature of the study and the limited monitoring data available only qualitative water budget assessments could be completed at this time.
The water budget estimates provide a relative comparison from region to region or aquifer to aquifer, rather than actual values of water availability or water use which are needed for quantitative land use planning and design. In addition, it should also be noted that local issues cannot be fully addressed at the regional scale of assessment and the enclosed report should therefore not be relied upon for determining the suitability or future sustainability of new projects or developments with respect to surface water or groundwater supply.
Waterline recommends that the RDN select one or two water regions to complete more detailed water budget assessments in accordance to the Ontario Ministry of Natural Resources Tier 1 or Tier 2 level assessment which was used by Waterline as a guide for the RDN project. This will allow the RDN to further develop the geodatabase for future quantitative water planning in all water regions across the RDN. Waterline recommends that the RDN select a water region within the Nanaimo Lowland area so that numerical modelling currently underway by the Geological Survey of Canada can be used to further refine aquifer water budget estimates in this area. Given the stress assessment for both surface and groundwater, the French Creek Water Region may be a suitable candidate for a pilot study which is recommended by Waterline.
The geodatabase structure developed by Waterline is intended for use by the RDN to develop a secure web application where surface water and groundwater information can be made available to the public. This will allow water managers and practitioners to have current and consistent data for use in water and environmental-related projects within the RDN which should allow for the advancement of knowledge with respect to water management and protection. It is anticipated that the web-based user interface would initially be similar to the RDN Water Map where key reports, maps and datasets are made available on-line. As the web interface is further developed, it should be possible for users to upload electronic groundwater and surface water data on-line. The data could include monthly/annual water use, water levels, water chemistry, aquifer properties interpreted from pumping test analysis, cross-sections, time-series data, hyperlinks to raw data, and a geo-referenced copy of any final reports. The RDN will likely need to develop guidelines, policies, and templates for data collection and submission as part of their planning and watershed management initiatives.