Abstracted Research Summaries
 
State of the Lake Environment Report; White Lake, 2007
 

In general the water quality in White Lake is good. There are three sampling stations: Sunset Bay, Three Mile Bay and Pickeral Bay (Bennett Bay) which were sampled three times in 2007. The mean secchi depth for 2007 was 4.1 metres indicating that White Lake is a moderately enriched (some nutrients) or a mesotrophic lake. Directly related to water clarity is the amount of nutrients, in particular phosphorus, entering the lake. The Provincial Water Quality Objective for Total Phosphorus for White Lake is 20 micrograms/litre (ug/L).The mean for euphotic zone (penetration of light) for 2007 was 12,8ug/L indicating a moderately enriched (some nutrients) or a mesotrophic lake. The mean for the sample taken one metre off the bottom was 10.7 ug/L, indicating an un-enriched (few nutrients) or oligotrophic lake.

 

Chlorophyll a is a measure of the algal density in the lake. The average chlorophyll a densities for White Lake in 2007 was 4.6 micrograms/litre, indicating a high algal density. It is not all good news, plants and animals are a direct reflection of their environment. The most critical time of year for conducting dissolved oxygen and temperature profiles is after August 31. Profiles are generally conducted at this time of year and at the deepest point in the lake. Aquatic vegetation and algae that has grown over the summer, has died off and settled on the bottom, using the available oxygen necessary to sustain aquatic life in the lower portion of the lake or the hypolimnion. The dissolved oxygen and temperature profiles were measured at all three sampling stations throughout the summer. The profiles indicate by late summer warm water fish species, such as bass, are still able to inhabit the majority of the water column with the exception of Pickeral Bay whose oxygen concentrations are poor by September. However, with White Lake's shallow depth, residents and users cannot afford to be complacent. Every effort should be made to reduce nutrient loading into the lake from land use activities.

 

White Lake was also tested for invasive species in 2007, in particular, for zebra mussels and spiny water flea, in partnership with the Ontario Federation of Anglers and Hunters. White Lake did not have spiny water flea or zebra mussel veligers (larvae) present in the samples collected. Residents and property owners need to ensure that all access points to the lake have posted signs indicating the precautions they can take to avoid the spread of invasive species into White Lake.

Residents and users of White Lake should continue a stewardship approach to limit the amount of nutrients entering the lake. There are useful tips throughout this report to help reduce your impact on White Lake. Continued Monitoring over time is essential to determine long term trends and changes. We all have a responsibility to preserve this precious natural resource for future generations.

 

 

 

Chemical Characteristics

 

Due to the relatively shallow lake basin and heavy wind action, thermal stratification does not usually occur. Summer water temperatures are usually in the 24-26C range. Alkalinity and pH values suggest that White Lake is well buffered and not particularly sensitive to acidic precipitation. In terms of trophic status, White Lake was considered as mildly eutrophic as early as 1969 (Ellah 1969). Eutrophic lakes are rich, biologically productive and have secchi disk readings of less than 3 metres and chlorophyll a values of greater than 6 ugl"'. Chlorophyll a values are indicative of high algal crops and algal blooms often occur during the summer. The diary of Peter's Point Fishing Club (see 'The Fishery') suggests that algae blooms occurred at least as early as 1940.

 

White Lake's shallow, "dish-shaped" basin and its low flushing rate make this system very productive from a biological basis. The nutrients and sediments which fuels the rich biological productivity in White Lake are thought to come from land runoff (45%), the atmosphere (42%), and shoreline development (13%) (Ferris 1985). The secchi disc measurements taken over time in White Lake show no clear trend (Figure 3). Chlorophyll 'a' values have fluctuated widely over time, but appear to have declined over the past 25 years. The amount of dissolved oxygen in the water column is a critical factor in determining the survival of many fish species. White Lake has sufficient dissolved oxygen to support warm-water fisheries. However, some surveys have shown that at water depths greater than 6 metres oxygen levels can fall below 5 ppm, a critical level for many fish (Ferris, 1985).

 

Several fisheries management issues have been identified on White Lake over the years. These include:

 

Water Levels - Controversy over the management of water levels has undoubtedly been the most prevalent issue on White Lake. Ministry of Natural Resources files include letters expressing concern about water level management dated in the early 1960's. Boaters and shoreline property owners prefer stable water levels during the summer and early fall. However, summer water level stabilization further reduces the natural flushing rate of the lake resulting in stagnant waters where silt and algae cover spawning shoals, resulting in water quality and fisheries concerns.

 

Accelerated eutrophication - White Lake has been considered to be moderately eutrophic for several years. Due to the shallow nature of this impoundment, its low flushing rate and the addition of nutrients from heavy shoreline development this process has been accelerated (Ferris 1985). Hamilton (1981) concluded that if nutrient loading was not significantly reduced, there would be the decline and loss of several species including walleye and possibly smallmouth bass.

 

Siltation of spawning shoals - Observations during 1959 and 1969 netting projects did not reveal any problems with siltation of shoals used by spawning walleye and smallmouth bass. In fact, Littkemann (1959) identified the presence of "numerous stony-rocky shores and shoals in different dimensions which provided good spawning grounds for walleye." The problem was first documented by Thomas (1975) and Bond (1977) concluded that encrustation of calcareous blue-green algae reduced the quality of walleye spawning shoals.

 

Impaired water quality - Ferris (1985) identified some water quality problems which included dissolved oxygen deficits in deeper (>6m) waters as well as some bacteriological contamination. The re-suspension of sediments from the lake-bottom by wind and wave action or by motor boat propellers has also been identified as an issue.

 

Shoreline development - Hamilton (1981) reviewed the dramatic increase in shoreline development from 1959-1980 and concluded this was a major cause in the accelerated rate of eutrophication. He believed that White Lake was an example of how unregulated cottage and shoreline development on a lake could have serious consequences on the fishery. Shoreline development was also identified as a problem by Ferris (1985) and vonRosen and McLeod (1985). Ferris recommended that backshore development be developed as an alternative to further lakeshore development in the future. There had also been previous recommendations to delay further lakeshore development until water quality and fisheries habitat issues had been resolved.

 

Shifts in fish community structure - Alteration of fish habitat and changes in lake trophic status have resulted in a shift in the resident fish community from species such as walleye and smallmouth bass which prefer mesotrophic conditions to those such as northern pike, panfish and largemouth bass which are more suited to eutrophic conditions. Walleye historically were the most highly sought species and were the mainstay of the local tourist industry at one time.

 

Conflicting resource uses- There are several conflicting resource uses on White Lake. These include anglers, boaters, shoreline property owners, the local tourist industries and hydro considerations. Ferris (1985) reported that 32% of lake use was from boaters while 68% was from anglers. Nowhere is the conflict more evident than with water level regulation and fish habitat protection.

 

Overexploitation - Overexploitation of highly sought sport fish stocks, particularly walleye, has been identified as a concern by vonRosen and McLeod (1985), vonRosen (1989) and Ferris (1985) Excessive algae and aquatic vegetation - Excessive mats of algae and aquatic vegetation have been identified as a summer problem by lake residents on several occasions.

 

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