Water Stewardship Information Sources

Citation Tetra Tech EBA Inc. 2014. Holland Lake and Stocking Lake hydrology update. Prepared for Town of Ladysmith.
Organization Town of Ladysmith
URL http://www.ladysmith.ca/docs/couverdon-boundary-extension/holland-lake-and-stocking-lake-hydrology-update-report-(ifu)-complete.pdf
Abstract/Description or Keywords The Town of Ladysmith (the Town) retained Tetra Tech EBA Inc. (Tetra Tech EBA) in January 2014 to carry out a
hydrology update for Holland Lake and Stocking Lake in support of the Town’s long-term planning for its surface
water supply system. In February 2008, Tetra Tech EBA completed the Stocking Lake Dam Hydrotechnical
Assessment for the Town. This earlier study included the hydrologic and hydraulic analyses performed for the
water sources available in the Stocking Lake watershed, the Holland Lake/Creek watershed, and the Banon
Creek watershed. Subsequent to the 2008 study, the Town required an update of the 2008 hydrological model
(water balance) to consider the impacts of current water licence limitations, current minimum flow requirements,
updated water demand projections and climate change. This report covers the hydrology update and findings
from the evaluation of five water supply options identified.
Additional hydrometric/climatic data and water consumption records/projections subsequent to the 2008 study
were collected and analyzed. The 2008 hydrological model developed by generating rating curves at reservoirs,
by taking into account average water losses throughout the water supply and distribution systems, by using a time
series of calibrated synthetic inflows at various points of interest was used as the basis for the current study.
Current water licence limitations (both at Stocking Lake and in the Holland Lake/Creek system) and minimum flow
requirements (10% of the mean annual discharge at point of diversion) were considered in the model update. As
requested by the Town, future water demand projections when the population of Ladysmith (excluding other
service areas) reaches the thresholds of 18,000 and 30,000 were considered in the current analysis. A review of
research on the impacts of climate change on the hydrology of the Vancouver Island region was also conducted.
Based on the findings in the research, changes were applied to the seasonal inflows developed for the Holland
and Stocking Lake watersheds to take into account the impacts of climate change. Based on discussion with the
Town and Koers & Associates Engineering Ltd., five water supply options were developed, resulting in a total of
25 model scenarios for the years of 2013, 2054 with and without climate change considerations, and 2080 with
and without climate change considerations.
Information Type report
Regional Watershed Vancouver Island South
Sub-watershed if known Bannon Creek
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