LAKE SURVEY UPDATE

by · September 6, 2013

The water was very clear and the weed growth was prolific, but not problematic.

Dr. Neil Hutchinson, Ph.D.
President, Principal Aquatic Scientist
Hutchinson Environmental Sciences Ltd.

On Thursday August 29, HESL scientists Dr, Neil Hutchinson and Dr. Tammy Karst-Riddoch completed the next routine water quality survey for Musslemans Lake.

We collected 3 sets of water samples:

1. a composite of the water column at the east end of the lake

2. a composite of the upper water column at the west end of the lake over the deep portion

3. a sample from 0.5m above the bottomalysis pof the at the same location at the west end.

We also collected profiles of temperature and oxygen at the east and west ends.

At this time of year the lake is strongly thermally stratified into an upper warm layer and a bottom cooler layer. The bottom layer has lost all of its oxygen – there is no oxygen in those parts of the lake that are deeper than 5m. This is a natural process for a kettle lake. It is not a great problem for fish as they simply stay in the upper water layers but the lack of oxygen causes the lake sediments to release phosphorus, a process known as “internal loading” that can cause algal blooms. We took samples to check for phosphorus in the deep section at the west end of the lake and took surface samples for taxonomic analysis of the algal community to see what the late summer community looks like.

Annual Pattern of Mixing  Young, M. (2004). Thermal Stratification in Lakes. Baylor College of Medicine, Center For Educational Outreach.

Annual Pattern of Mixing
Young, M. (2004). Thermal Stratification in Lakes. Baylor College of Medicine, Center For Educational Outreach.

As autumn progresses the lake will begin to cool and the thermal stratification will weaken until Gordon Lightfoot’s “gales of November” cause the lake to thoroughly mix, restoring oxygen to the bottom waters.We talked with a lake resident on her dock on August 29, and she told us that the water quality this year had been better than usual, with less weed growth than usual and the water remaining clear over the summer. Our own observations confirmed that the water was very clear and that the weed growth was prolific, but not problematic. We confirmed that Eurasian milfoil, a problematic invading species, was a dominant component of the aquatic plant community.HESL expects to visit the lake twice more, and prepare a report by the end of October.We thank Geranium Corporation for their support of this study.

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