Water use in the Cheakamus River, British Columbia

The Cheakamus River is a focal point of a recreational corridor in south-western British Columbia, best known by the presence of the resort Municipality of Whistler.  Whistler is a top ranked, year-round destination resort that was the site of alpine and Nordic events during the 2010 Winter Olympic and Paralympic Games. Increased population size of Whistler over the past three decades has resulted in infrastructure upgrades including the wastewater treatment plant, which is now one of the most advanced facilities in the world. Treated wastewater is discharged to the Cheakamus River.  In 1996 through 1998 Limnotek completed a detailed analysis of the role of the treatment plant in contributing to biological productivity in the Cheakamus River. The analysis partitioned nutrient transport between all sources in the upper river and it examined positive and negative effects of that loading on algal accrual, benthic invertebrate abundance, aesthetics, and food web dynamics that support valued salmon in downstream reaches. A simulation model based on functional relationships developed from field sampling was constructed to explore potential changes to nutrient flux and algal accrual at various locations in the river as a function of upgrades at the wastewater plant. Those data contributed to decisions on treatment requirements in ongoing plant upgrades.

 

In 2008 and 2009 the work was expanded to provide environmental information for planning water use in the Cheakamus River.  Downstream of Whistler, the Cheakamus River is impounded for diversion of some water for power production. Remaining water in the lower Cheakamus River is used by several species of salmon that have commercial value and hold importance for people living in the area, including First Nations communities. The salmon support the largest accumulation of bald eagles anywhere in the world that gather to feed on salmon carcasses.  Increasing demands for disposal of treated wastewater, for power production, for recreation, fisheries and fish habitat has introduced many complicated but necessary questions about use of Cheakamus River water. 

 

One of these questions is; What flow is the best flow to support fish, yet maintain profitable production of power?  Limnotek was retained by BC Hydro and the Resort Municipality of Whistler to design a monitoring project and collect and analyse chemical, physical, and biological data to contribute to answering this question. Using multi-year data we derived functional relationships in support of decision-making by a large team of people representing government agencies, BC Hydro, First Nations, and community interest groups.   In this process we simplified findings from statistical analysis and presented the information in a way to reduce uncertainty in making decisions.  Follow-up monitoring is being planned for 2013 to determine if assigned flow releases are meeting water use goals.

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