"At Capacity" — What Does It Mean?
When a lake is determined to be "at capacity" in a biological sense, it means that any development which has the potential to add additional phosphorous or other nutrients, directly or indirectly,into the lake will not permitted within 300 metres of the lake.
How is a Lake Determined to be "At Capacity"?
There is science behind this designation based upon lake trout biology and life history patterns. Lake trout are a very
temperature and oxygen sensitive species. In addition, juvenile lake trout need to be able to escape their parents
or else end up on the menu. To do this, the juveniles inhabit the deeper, colder waters of a lake, generally below 28 metres whereas the adults inhabit the upper levels, typically with water in a temperature range from 8 to 12°C.. When nutrients increase in a lake, plant and algae production increases. The decomposition of plants and algae uses up oxygen and thus places significant stresses on lake trout particularly in late summer and beyond. It has been determined that the average oxygen level of water below the thermocline (see definition below) should be above 7 parts per million (ppm) in order for lake trout to adequately carry out their life processes.
To determine oxygen levels, the lake is sampled in early September. A temperature/oxygen profile is taken for the entire depth of the lake and the average oxygen level is determined for the waters below the thermocline. The capacity designation is then based upon whether the oxygen level is above or below 7 ppm. Some lakes have oxygen levels that are very close to 7 ppm, either slightly above or below. These lakes are sampled more frequently to try to determine exactly where they might lie as there may be small discrepancies in oxygen levels due to the weather of that year or the sampling equipment. A few lakes show wide fluctuations — one year being way above and the next time way below the 7 ppm threshold. These lakes are also sampled more frequently to determine a more accurate level. The MOE (Ministry of Environment) does the calculations and would normally make the call. But sometimes MNR can do it as well.
What are the implications for future development on the lake?
If a lake has a reading consistently above 7 ppm, then new development can occur. If a lake is consistently below 7 ppm, then no new development can take place as described above. However, in some instances, there may be existing approved lots that have not yet been developed.
Haliburton County lakes listed "At Capacity"
Art, Basshaunt, Beech, Bitter, Davis, Delphis, Devil's, Eagle, Eels, Fletcher, Glamor, Havelock, Hudson,Kabakwa, Klaxon, Kushog, Little Boshkung, Livingstone, Long, Maple, Marsden,Monmouth, Moore, Mountain, Nunikani, Pusey, Silent, South Anson, Stormy, Twelve Mile, Two Islands, Wilbermere
Thermocline - The mid layer of a lake in which there is the most rapid decrease in water temperature. This is characterized by at least a 2 degree centigrade drop per metre.
Author — Gerry Moraal — MNR Minden
What is a Dead Zone?
It is an area devoid of fish or any aquatic life. The cause is little or no oxygen to support life. In a dead zone, nothing at all can live effecting wildlife such as loons that depend on the fish, frogs etc. Oxygen depletion is caused by poorly maintained septic systems, fertilizer runoff, inappropriate development and the loss of natural shorelines and wetlands with their essential filtering effect.The fact that one fairly large Haliburton lake has identified several dead zones in their lake should be an indication that the threat we pose to our lakes health must be taken seriously.
What About the Redstone Chain of Lakes?
According to a recent report Haliburton has developed and de-naturalized more shoreline than almost anywhere else in Ontario including Muskoka. Difficult to believe given the expanse of natural shoreline on our chain of lakes. We are asking to have that claim verified and will let all know. While Redstone may be an exception to other lakes in Haliburton we continue to see shorelines change. Natural shorelines are cleared and replaced with rock walls, high waters denigrate natural shorelines of logs, only to be used as firewood by owners clearing their beaches of unattractive wood.