Lake Weston Water Availability and Climate Change Assessment

Extracted text (beginning)

July 26, 2022 
Project No.22-01
 
 
GW Solutions Inc. 
Unit 24 – 4800 Island Hwy, Nanaimo, BC, V9T 1W6 
T: (250) 756-4538      abarroso@gwsolutions.ca; dbethune@gwsolutions.ca 
 
 
 
 
Lake Weston Water Availability and Climate 
Change Assessment 
Prepared for: 
Capital Regional District 
PO Box 1000 
Victoria, BC V8W 2S6 
 
Prepared by: 
GW Solutions Inc. 
July 26, 2022 
 
 
 
Appendix 1
116

Lake Weston Water Availability and Climate Change Assessment July 26, 2022 
 
Page i    Pr  oject No. 22-01 
Executive Summary 
Capital Regional District (CRD) Parks & Environmental Services and the Salt Spring Island 
Local Trust Committee of the Islands Trust required a climate-adapted water availability 
study for the Lake Weston / Weston Creek watershed on Salt Spring Island (SSI).  The 
purpose of this study is to assess future water supply availability for the Lake Weston 
watershed in consideration of current water licences and predicted climate change 
scenarios. The Fulford Water System is currently the only local community water service 
provider in the Lake Weston/Weston Creek watersheds.  There are also 24 point-of-
diversion licences to extract water for domestic and irrigation supply from Lake Weston. In 
consideration of future growth scenarios within, and outside of, the Lake Weston 
watershed, it is necessary to identify the safe yield of water supplies while ensuring water 
requirements for environmental flow needs are preserved to ensure aquatic ecosystems 
(wetlands, creeks, lakes, etc.) are protected. 
To meet the goal of project, GW Solutions has developed a water balance model (based on 
the Thornthwaite-Mather approach) to assess the water availability within the watersheds 
that contribute to the main study area, Lake Weston watershed. We estimated water 
withdrawals/usage from groundwater and licenced surface water resources and compared 
this usage to water availability. Finally, the estimated available water (for both groundwater 
resources and surface water features) under different climate conditions based on global 
climate models ( scenarios; 2030s, 2050s, and 2070s) has been compared with the current 
water usage in the study area. This comparison enables us to understand if the study area 
is likely to experience stress due to withdrawals that exceed available supply. The results 
also help the CRD to determine if there is potential for community expansion within the 
study watershed based on sustainable water supply.  
The Lake Weston Watershed is dominated by the star-shaped approximately 500-metre-
wide Lake Weston and a limited number of stream drainages;  however,  the majority of 
creeks and rivers are reported to not flow all year round or have very limited flow during the 
dry season. Lake Weston has a maximum depth of 12.2 meters and is connected to the 
upper groundwater system. The lake occurs within a topographic depression at the 
intersection of two faults which has enabled the lake to form.  Groundwater feeds

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