Water Quality 2010
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On July 14th, 2010 Ministry of Environment Impact Assessment Biologist Chris Swan, her nine year old son Justin (getting a science lesson during the summer break) and our 12 year water testing veteran Karl Schmitz went out on the lake to do some in-depth evaluation of Bridge Lake's water quality. They anchored their boat for several hours at one of the lake's deepest spots, right in the middle between Grassy Island and Long Island.  Temperature and Oxygen Levels
On a long cable a probe was slowly lowered down to the bottom of the lake, recording at every meter various water quality data like pH, temperature, electrical conductivity, oxygen level and turbidity. A provisional look at the data suggested an excellent water quality: the oxygen levels stayed in the ‘green zone’ right down to the bottom of the lake. “The fish must be really happy in this lake”, remarked Chris. While Karl recorded the data, Chris programmed, calibrated and tested a smaller device that ‘only’ measures temperature and oxygen levels (right). This device will remain here with Karl and he will go out every week for the rest of the season and repeat these tests, collecting valuable long term data for Bridge Lake. The results of Karl's weekly measurements can be found here. Another contributing factor to the well-being of our stocked fish is the pH of the water. Both kokanee and rainbow trout prefer slightly alkaline water, so the measured value of about 8.5 is just what they like! Kokanee food
In the mean time, Justin had readied the funnel like net to collect zooplankton samples. Lowered to the lake bottom and slowly retrieved, the usually not noticeable zooplankton (tiny aquatic animals the size of a pinprick) remained highly concentrated in the collector jar attached to the bottom of the net. This sample (left) shows mainly red copepods and green-brown transparent daphnia (water fleas), both species a major part of the kokanee diet. Once the final data of this outing are available, we will of course report them right here. A great day on the lake, Thank you Chris (and Justin)! |
