Waterfowl

Carpenter Lake Reservoir is the largest of the three reservoirs of the Bridge River Power Project (about 50 kilometers in length). It is a mid-sized stream approximately 120 km long, flowing south-east from the snowfields of the Coastal Mountains and joining the Fraser River near Lillooet. The lake is about 185 kilometers north of the province's major city of Vancouver and is formed by the diversion of the Bridge River by Terzaghi Dam into Seton Lake via a tunnel through Mission Mountain, which separates the Seton and Bridge drainages. Carpenter Lake is about 50 kilometres in length, and represents a major riparian habitat for the region. This structurally complex area welcomes a diversity of vegetation species, and supports rich communities of breeding birds: Canada Geese, Snow Geese, Ross's Geese, Mallards, Pintails, Harlequin, Canvasback, and Goldeneye. The riparian habitats are a relatively rare landscape features (Skagen et al. 2005): in western North America, they comprise less than 1% of terrestrial landscapes (Knopf et al. 1988). In British Columbia, about one-half of forest-dwelling terrestrial vertebrate species depend on riparian habitats for breeding (Bunnell et al. 1999). Migratory waterfowls especially require those wetland habitats that support an abundance of invertebrate prey, in order to help them refuel during their long migratory journeys. The relation between wetlands and birds is shaped by many factors but the most important of them is the availability, depth (at least 3 to 5 cm) and quality of water. Drawdowns play a critical role by periodically exposing the sediments and their underlying seed bank and encouraging emergent vegetation growth, which provides food for migratory waterfowls. However, many of these habitats are ephemeral in nature and may not be available during the critical migratory period of numerous birds (from late April to early June in the spring, and from mid-September to late November in the fall).

Carpenter Lake previously offered an abundance of mudflats, undisturbed shorelines, shallow flooded fields, and hallow wetlands. However, because breeding habitats are located in the reservoir drawdown zones, the hydroelectric operations and management occurring in the Bridge River area seasonally change water levels on the lake and have significant impacts on the productivity of resident bird populations that use these sites. The waterfowl migration is reduced in a significant way in the Bridge River Valley: in previous years, hundreds of waterfowl were present in Carpenter Lake, however, in the year 2014 only a few waterfowl birds were seen.

Issues:

• Water management of the reservoir may be impacting migratory bird populations

Goals:

• Monitor waterfowl populations, diet, and habitat near Carpenter Lake
• Survey the quality and availability of water to waterfowl, such as the quality and quantity of water flowing through the wetland areas adjacent to carpenter lake.
• Determine if the reduction in waterfowl near Carpenter Lake is correlated with hydroelectric operations of the reservoir
• Rehabilitate wetland habitat by proposing a plan to improve the management of the water in the reservoir
• Increase the waterfowl food supplies by encouraging invertebrate production by identifying the proper regime of drawdown and flooding to stimulate the growth and decomposition of plants that are a detrital source of food for the invertebrates
• Raise local populations and tourist awareness of the protection of riparian habitat and the importance of water management