Water Quality

Water Quality Update by LWCA Director Ian Mackenzie, November 2017

Maintaining the high quality of our Weslemkoon water is the highest priority of the LWCA. Key values being safety for swimming, visual/clarity of water, and the health of fish populations.

LWCA water monitoring program

Various water testing has been done over the years. The current program has been influenced by what we know to be important to swimming, clarity & fish, and within the constraints of our budget (lab testing is expensive). Currently we do two types of tests:

  1. Deep water sampling of temperature and dissolved oxygen (DO). We’ve been monitoring two deep water locations. We take a measurement of temperature and DO every metre. The LWCA aims to expand the number of deep water test locations in the summer of 2018.
  2. Chemistry and Bacteria – we monitor 21 locations around the lake, and we do these tests every three years in order to monitor trends.   Measurements of Nitrogen, Phosphorus, E-Coli and total Coliforms are taken.

Historic Trends

  1. The deep water test results are shown in Figure 1. The dissolved oxygen trends are relatively stable across the 1989-2008-2017 samples. The deepest section of the Otter Lake location actually looks a little better in 2017 than in 2008.
  2. Chemistry test results show a generally worsening water quality trend, particularly in the 4 south end sampling locations. Nitrogen levels are well above the target range at all test locations while Phosphorus levels are within the target range at all locations. E-Coli only appears in any significant level in the south end locations. Total Coliforms are generally above the target level at all locations, and significantly higher at south end location where creeks flow into the lake. To look at the details, read the following document which provides data over 3 years:


Implications and what we can do to Influence

Lake Weslemkoon is classified as a highly sensitive lake trout lake. Tests show dissolved oxygen remains above the survival minimum of 6 mg/litre, but below their preferred range of 9.6-11.7 mg/l.   It’s important to keep our lake trout, and important to keep our ‘highly sensitive lake trout lake’ classification, as the level of further human development on the lake is constrained by having this classification.

Nitrogen and Phosphorus levels influence growth of aquatic plants and algae.   The levels are significantly higher at the south end of the lake due to the higher level of development both on the shore and upstream of the creeks flowing into the lake.

water quality chart
The above chart shows Average data for the four sampling years. Average data is not the best since individual levels vary quite a bit, but the above chart of averages shows a worsening trend.

What can cottagers do to influence improvement to water quality?

  • Have a septic system & be sure it’s working properly (see Septic report for how to get inspected)
  • Minimize water use – where possible take laundry home and avoid use of dishwasher
  • Choose soaps that are environmentally safe (e.g., contain no Phosphates) and don’t wash directly in the lake
  • Don’t use fertilizers and pesticides
  • Reduce erosion effects – maintain trees, shrubs & ground cover in the Riparian Zone by the lake