Vaseux–Bighorn National Wildlife Area Management Plan: chapter 3

3. Management challenges and threats

The management challenges and threats faced by Vaseux-Bighorn National Wildlife Areas (NWA) are managed in the context of the broader landscape of the Okanagan-Similkameen region. Since the first management plan was adopted for Vaseux-Bighorn NWA in 1986 (Environment Canada 1986), this region has undergone tremendous development pressure. B.C. Stats predicts that between 1986 and 2036 the population of the Okanagan-Similkameen Regional District will experience a 51.4% increase, with predicted growth rates ranging between 3 and 5% annually. The burgeoning wine industry, ranchland tenures, forestry, transportation, tourism and, in particular, high-value vineyard and tree fruit crops continue to drive the local economy. The expansion of the vineyard industry, however, contributes to habitat loss and fragmentation, particularly for Antelope Brush, a rare habitat type in British Columbia and Canada. According to the 2006 Census of Agriculture, in 1989 there were 1100 acres of wine grapes in the Okanagan Basin, while in 2004 there were almost 6000. Further growth in the industry has occurred since 2004, and more growth is expected. Other challenges are summarized in Table 4.

In this context, habitat conservation (particularly for species at risk) and maintenance of connectivity between the remaining habitats in the valley become increasingly important functions within and around the NWA.

The channelization of the Okanagan River to control flooding has disrupted the natural flooding cycle in riparian areas surrounding Vaseux Lake (Chapman 1997b). The stages of Vaseux Lake are controlled by McIntyre Dam, which is located below the lake outlet to address seasonal flooding on the Okanagan River. In addition to flood protection objectives, the channel facilitates drainage of adjacent agricultural lands. Any overflow from this dam is diverted into an irrigation channel to provide water to the surrounding agricultural areas (Allen and Toews 2009). Areas that are particularly affected by such changes in hydrology are the riparian habitats along the lake, which require sufficient flooding to maintain biological processes. Since the 1980s, Ducks Unlimited Canada has operated a dam at the north end of Vaseux Lake to maintain water levels within the marsh area of the Northwest Marsh Unit.

There are site-specific contamination risks in the Irrigation Creek (Old Mill), and the Southeast and Westside units (adjacent to the Kettle Valley Railway). A series of investigations has been undertaken to determine the level of potential contamination. A detailed Phase I Environmental Assessment was completed at Vaseux-Bighorn NWA in 2003 by SEACOR Environmental Inc. (SEACOR 2003). A site assessment (Phase III) was done for the NWA by SLR Environmental 16 Consulting in 2009, to delineate soil contamination in the Irrigation Creek Unit (Old Mill), the Southeast and Northwest Upland Units, and the Westside Unit (Kettle Valley Railway). The results of the investigations from 2005 and 2009 showed that for the Irrigation Creek Unit (Old Mill site), one soil sample exceeded the CCME guidelines for naphthalene (a polycyclic aromatic hydrocarbon [PAH]). It is therefore recommended that further soil sampling take place to delineate the extent of PAH contamination. Once delineation of the contaminant has been achieved, a risk assessment will be conducted to determine the level of risk present at the Old Mill site (SLR Environmental Consulting 2009). Overall, however, the risk of contamination in the NWA is low.

Although agricultural areas are outside of the NWA, some are adjacent to the wildlife units and are therefore still able to cause potential contamination within the NWA. Adjacent vineyards and ranches can potentially contribute to the input of nutrients, salts, sediment, agricultural chemicals, litter and microbes into the wildlife area due to the migration of contaminants via surface runoff or movement through soils. In addition to agricultural sources of contamination, there is also an effluent plume on the east and south sides of Vaseux Lake, due to the lack of appropriate sewage facilities for residential properties located there. This could potentially affect the riparian communities along the NWA units that are adjacent to Vaseux Lake. There are currently no water quality monitoring sites in place on Vaseux Lake.

Other challenges include: the restoration and management of important habitats and ecosystems, particularly for species at risk; the control of invasive species, including the control of extensive patches of Knapweed, Sulphur Cinquefoil, and Purple Loosestrife; control of unauthorized access to the NWA that results in wildlife and habitat disturbance and spread of invasive species; reducing fire risk by managing forest encroachment into grassland and urban areas and reducing fuel loads; and improving water quality in the NWA.

Overall, the NWA is in poorer condition than it was at the time of establishment, owing to alien and invasive plants, fire suppression and unauthorized recreational access. In a 2007 report on the state of federal protected areas, Environment Canada rated the ecological integrity of the NWA as fair, and noted that the NWA is currently under moderate threat. It is anticipated to be under a higher level of threat in the future due to population growth, recreation pressure, and alien and invasive plant species.