This report presents water quality information for Kalamalka, Wood, and Ellison Lakes, collected by the BC Ministry of Water, Land and Air Protection, Pollution Prevention Program, or its equivalent (Environmental Protection, Waste Management, Pollution Control Branch) from approximately 1969 to 1999. The data are useful to document trends in water quality and to assess the possible impacts of waste discharges on ground water flowing into these lake systems. The lake quality data can also provide evidence about the effect of non-point source (NPS) contaminants on the lake system.

These lakes, located in the north Okanagan Valley, are the first three in the chain of valley bottom lakes; the other lakes downstream are: Okanagan, Skaha, Vaseux, and Osoyoos Lakes (Figure 1). All of the lakes receive water from headwater lakes, most of which are located at higher elevations above the Okanagan Valley; data for these headwater lakes have been compiled during the Okanagan Basin Study (Koshinsky and Andres, 1972). Previous studies have reported Kalamalka Lake as oligotrophic, or relatively low in productivity, and Wood and Ellison Lakes as eutrophic, or relatively high in productivity (Anon. 1974a, Anon. 1985, Bryan 1990). As the lakes are intimately linked hydrologically, the physical differences between the lakes (Table 1) largely account for the different water quality of each lake. None of the lakes receive any point source discharge of nutrients, thus each lake is largely influenced by anthropogenic or human related non-point source nutrient inputs from septic tanks, agriculture, urbanization, and forestry. In addition, internal processes affecting nutrient cycles differ among the lakes as described below with physical attributes of the lakes.

Algal blooms on Wood Lake in 1971 prompted the first detailed limnological study of these three lakes and established nutrient loading estimates (Anon. 1974a). A subsequent review and recalculation in 1980 concluded that 60% of the non-point source phosphorus load to Kalamalka Lake was from animal wastes, 30% from septic tanks and 9% from logging (Anon. 1985). For Wood Lake, 42% of the phosphorus load was from septic tanks, animal wastes and logging contributed 27% and 24% respectively; however as with any model, these were estimates prepared with the best assumptions and data available at the time.

Although water flowing from Ellison to Wood and then to Kalamalka Lake is not impeded, a dam at the outlet of Kalamalka Lake affects lake levels and controls the flows from Kalamalka Lake into Okanagan Lake via Vernon Creek. There have been a number of changes to water movement in the system worthy of mention. In 1908, a canal was excavated between Wood and Kalamalka Lakes to allow navigation between the two. As a result, water levels dropped 0.6m in Wood Lake and rose 0.25m in Kalamalka Lake (Anon 1974a). Water diversions from upstream of Ellison and Wood Lake between 1930 and 1970 are thought to have increased the water residence or renewal time of Wood Lake from 14 to 30 years during that period. In 1971, the Hiram Walker Distillery began pumping water from Okanagan Lake to cool its still. The warm water resulting from this process was discharged into Vernon Creek at the north end of Ellison Lake. This cooling water contained much less phosphorus and nitrogen than the ambient water of Ellison or Wood Lakes. It was discharged to Vernon Creek just upstream of Ellison Lake, at an average rate of 13,600 m³/d from 1972 to 1990. After the distillery stopped operating in 1992, the cooling flows were significantly reduced to maintenance flows of less than 380 m3/d, and ceased entirely in June 1995.

The low-nutrient water diluted the high-nutrient levels in Ellison and Wood Lakes, however the additional flow pushed higher-nutrient Wood Lake water into low-nutrient Kalamalka Lake. The Kalamalka-Wood Lake Basin Study included predictions about eutrophication of Kalamalka Lake due to the extra load of nutrients from this source (Anon. 1974a). Subsequent reviews had suggested that nitrate in Hiram Walker wastewater discharged to ground might enhance spring phosphorus uptake by phytoplankton thus avoiding blue-green algal blooms in mid-summer (Jasper and Gray 1982). Other studies suggest the reduction in water residence time for Wood Lake, perhaps in concert with other hydrologic (Walker 1993) and climatic trends, has resulted in an improvement in Wood Lake water quality (Nordin 1994).

Figure 1. The north Okanagan and the first three main-valley lakes, Kalamalka, Wood and Ellison, in the Okanagan basin drainage.

Some of the physical features of these lakes are shown in Table 1. Kalamalka Lake is considerably larger in volume and surface area, and deeper than Wood or Ellison lakes. Ellison Lake is so shallow that it does not develop thermal stratification in the summer. Consequently its water circulation and nutrient transfer between sediment and water occurs daily as is typical of ponds. Wood Lake is sufficiently deep to develop stable thermal stratification but still shallow relative to its surface area so that the volume of water in its hypolimnion is small and easily depleted of oxygen. Consequently, there have been years when the bottom waters were anoxic in late summer and fall allowing phosphorus to move from the bottom sediment back into the water column. Kalamalka Lake, in contrast, has a large volume of hypolimnetic water with very little oxygen depletion.

As mentioned above, the theoretical flushing times for the lakes were altered by the Hiram Walker Distillery diversion from 1971 through to approximately 1996 and has now returned to pre-diversion values. During that period, approximately 4.9x10⁶ M³ per annum was diverted from Okanagan Lake into the Kalamalka Wood lake basin by Hiram Walker in Winfield. This transfer approximately restored flows lost upstream of Ellison Lake due to irrigation diversions (Anon. 1974a).

Table 1. Morphological Characteristics of Kalamalka, Wood and Ellison Lakes

1. Anon. 1985. Phosphorus in the Okanagan Main Valley Lake: Sources, Water Quality Objectives and Control Possibilities.
2. Nordin, R. in The Canadian Book of Lakes (Allen et.al. 1994)
3. Okanagan Basin Study (Anon. 1974b)
4. Anon. 1974 Kalamalka-Wood Basin Water Resource Management Study
5 Lower number reflects reduced water residence time during Hiram Walker discharge of Okanagan Lake water into Ellison Lake.
6 Theoretical increase in water residence times forecast by reduction of Hiram Walker diversion flows of 510 m³/hr
7 Water Survey of Canada 1991 records for Vernon Creek at outlets of Ellison and Kalamalka lakes and inlet of Vernon Creek to Wood Lake