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 |
Aquifer # | |
Comments | |
Project status | |
Contact Name | |
Contact Email |