Carlton Aquifer (205)
The Carlton aquifer is a small (2.6 km
2
)
confined aquifer comprised of poorly sorted outwash
sand, gravel and silts (Vashon Drift) located between Shawnigan Lake and Mill Bay, and is
surrounded by bedrock aquifers. Overyling deposits include thick silty sand and gravel, till,
hardpan and clay mixtures resulting in low vulnerability to surface contamination. The aquifer
is moderately productive with a range of reported yields from 0.19 to 3.16 L/s. Water use is
for multiple purposes. Water reliance is conjunctive, water licenses exist on North and South
Taggart Creek, Ericson Creek and a few springs in the area.
Mi l l Bay Aquifer (206)
The Mill Bay aquifer is a small aquifer (2.7 km
2
)
that is both confined and unconfined and
comprised of coarse grained deposits. It is bound to the north by Shawnigan Creek, to the
west by Handyson Creek, to the south by an upland area, while to the east it pinches out just
before the Saanich Inlet. Productivity is moderate with reported yields ranging from 0.09 to
22.1
L/s. Groundwater flow and availability is concentrated in a bedrock channel where the
aquifer is thickest. The vulnerability of the Mill Bay aquifer is variable but is generally
classified as highly vulnerable due unconfined conditions in the upslope recharge area. In the
northern central portion of the aquifer a clay layer occurs. The clay overlies a portion of the
buried channel that creates artesian aquifer conditions in that area. Silty sands and gravels
also confine the aquifer to a lesser degree throughout much of the area. Lowen (1994a) has
determined the direction of flow as north/northeast and the recharge mechanism as infiltration
from precipitation and lateral flow from upslope recharge zones in the southern portion of the
aquifer. Groundwater from this aquifer is used for municipal and domestic purposes. Saline
groundwater has been noted adjacent to the Trans-Canada highway (Kohut, 1987) and may
be due either due to saltwater intrusion from Saanish Inlet induced by groundwater pumping
in the aquifer or from application of road salt. Water reliance is conjunctive. Several water
licenses exist on Handysen, Wheelbarrow, Bird, Goodhope and Wilkins Creeks. Wheelbarrow
Springs are also a source for the municipal water supply. The Bamberton Aquifer (no. 207)
occurs beneath the Mill Bay Aquifer and can supply additional domestic and municipal water
needs to Mill Bay residents.
South Cowichan Aquifer (196)
This 45.8 km
2
shale and sandstone bedrock aquifer includes the area south of the Cowichan
River to the base of the Koksilah Ridge. The eastern boundary is the Lower Cowichan River
floodplain and the western boundary extends to Holt Creek. Overlying deposits include
marine and glaciomarine sediments, ground moraine and glaciofluvial deposits. The aquifer is
characterized by low productivity with reported well yields of 0.02 to 0.63 L/s. The direction of
flow has not been determined but it is hypothesized to flow toward the Cowichan River.
Recharge is suggested by precipitation, runoff from the mountains to the south and/or inflows
from surficial water bearing zones. Water use is domestic while water reliance is conjunctive.
Several water licenses exist on Glenora, Vaux, Holt, Motek and Kelvin Creeks. Water
licenses also exist on Tattum Brook, Vaux Swamp, springs and other unnamed streams in the
area. The Glenora aquifer is a confined surficial aquifer that overlies the South Cowichan
bedrock aquifer.
