Water Stewardship Information Sources

Citation CH2MHill. 2006. Summary Report: Comox Lake Watershed Assessment. Prepared for Regional District of Comox-Strathcona.
Organization Regional District of Comox-Strathona
URL http://www.comoxvalleyrd.ca/assets/Department/Documents/Comox_Lake_Watershed_Assessment_Summary_Report_Final.pdf
Abstract/Description or Keywords The purpose of the Comox Lake Watershed Risk Assessment was to identify the major risks
to the Comox Lake water source so that a future program to mitigate these risks could be
developed with major stakeholders in the area. The watershed assessment followed the
portions of the Province of British Columbia’s proposed “Comprehensive Drinking Water
Source to Tap Assessment Guideline” that are related to source protection. These elements
included the characterization of the water source, an inventory of the potential contaminant
sources, a description of the water supply system, and the characterization of the risks
posed to the water source.
The Comox Lake watershed consists of 46,000 ha of mountainous terrain supporting glaciers
year-round. The watershed is largely undeveloped and contains mostly coniferous forests at
various stages of maturity. Forestry is the primary industry in the area, and there are several
forest roads throughout the basin.
There are two intake points for the water supply system. The primary intake point is off the
BC Hydro penstock. The penstock conveys water from the Puntledge River to the hydroelectric
generating station 5.1 km downstream. The second intake point is a pump station
that draws water directly from the Puntledge River at a point near the generating station. In
total, up to 68.2 ML/day can be drawn from the water source. When the penstock intake is
in use, the total contributing watershed area is 47,500 ha. When the pump station intake is in
use, the total contributing watershed area is 59,000 ha.
The public has open access to large portions of the watershed. There are 51 cabins located on
land leased from TimberWest in the southern portion of Comox Lake. Many of these cabins
are only accessible by boat, and most are used only during the summer. There are an
additional 26 cabins on the eastern shore of the lake, of which seven are used year-round.
There are two campgrounds on the lakeshore – the Cumberland Campground in the southeastern
part of the lake and the Courtenay and District Fish & Game Club near the Comox
Lake Dam. Both campgrounds have day-use beach areas and provide washroom facilities
for users. Boats can access all areas of Comox Lake and there are several sections of the
Puntledge River that are popular with river kayakers. Boat launches are located at the
Cumberland Campground and at the Fish & Game Club. Multi-use trails extend from the
Comox Lake dam along both sides of the Puntledge River past the Highway 17 crossing.
These trails are typically used by hikers, mountain bikers, and horseback riders. Motorized
vehicles are prohibited from these trails, but many are able to access the vast array of trails
that exist off forest roads throughout the watershed.
The identification of hazards to the water source was separated into two tasks. The first was
the identification of intrinsic risks to the water source, while the second involved the
identification of contaminant sources generated by human activities. Intrinsic risks are those
that would exist naturally in the watershed regardless of human use or development. GIS
mapping, aerial photographs, personal interviews, surveys of cabin users, and past reports
were used to complete this task. The following intrinsic risks to the water source were identified:
• Erosion and slope failure
• Slides within the watershed
• Wildlife within the watershed
• Harmful leachate
• Flooding
• Decaying organic matter
• Climate change
• Internal lake processes
The following contaminant sources were identified:
• Forest harvesting
• Gravel and other mining activities
• Agriculture
• Roads and transportation
• Housing – including both permanent and part-time residences
• Recreational activities - including boating, camping, hiking, mountain biking, and other
activities
• Intentional harm to the water source by individuals
Three characteristics were used to qualify each identified contaminant source and intrinsic
(natural) hazard – the likelihood the event would occur; the consequences of the event if it
were to occur; and the vulnerability of the water source to the event. Specific criteria for
each of these characteristics were developed within the bounds of the provincial guidelines
in order to assign a qualitative value for each of the identified hazards. The product of the
first two criteria, likelihood and consequence, was defined as the unabated risk from a given
hazard. The unabated risk is the risk each hazard poses to the water source assuming there
were no barriers to contamination. The vulnerability criterion was based on analysis of the
barriers to contamination. Barriers in the watershed include varying methods of transport
(overland flow, groundwater flow, stream flow, and lake flow), time of travel (which can
allow natural processes to reduce contamination), the settling of contaminants (especially in
Comox Lake), as well as chlorination at the intake point. The product of the unabated risk
and the vulnerability was defined as the abated risk. This is the actual risk a given hazard
poses to the water source in its current state.
The following hazards were found to have the highest abated risks:
• Transportation over the Puntledge River Bridge near the Comox Lake outlet
• Transportation on roads directly adjacent to the Puntledge River
• Boating on the Puntledge River upstream of the penstock
• Intentional harm to the water source by individuals Other areas of notable concern include recreational boating on the lake, wildlife in the
eastern area of the lake and near the Puntledge River, camping in non-designated areas near
the lakeshore, and the cabins in the eastern part of Comox Lake. Risk of contamination from
coal spoils on the eastern lakeshore and aircraft crashes near the penstock was also high,
notwithstanding the low likelihood of these events actually occurring.
Further work will be required to complete the full source to tap assessment process. Tasks
yet to be completed include: an evaluation of water system management, operation, and
maintenance practices; an audit of water quality and availability; a review of the financial
capacity and governance of the water system; and a further assessment of water supply
elements that were not included in the scope of this project. Recommended actions to
improve drinking water protection will follow the completion of the total assessment
process.
Information Type report
Regional Watershed Vancouver Island North
Sub-watershed if known Comox Lake
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