Summary of Findings and Recommendations
This year, four measures are higher than usual: fecal coliforms, phosphorus, colour and turbidity. These changes suggest an increase in dissolved organic substances and material in suspension in the water. These are all associated with a risk for algae blooms. As Notreau found similar increases in the other lakes they tested this year, the change may be weather-related.
Note: Public health norms state that drinking water should have zero coliforms, whether fecal or otherwise. The lake tests measure only fecal coliforms. Household tests provide information about other coliforms. Therefore, it is recommended that lake water be treated by boiling or with a UV filter system before drinking. [This is even truer for people at risk, such as children, the elderly, and the sick. For more information on coliforms in drinking water, see http://www2.gnb.ca/content/dam/gnb/Departments/h-s/pdf/en/HealthyEnvironments/water/Coliforme.pdf ]
We can congratulate ourselves on having a healthy lake in which we can swim safely. We will continue to monitor the health of the lake.
We need to continue to do our share by following these guidelines:
Septic systems need to be cleaned regularly (every two years for frequent residents, every three years for weekenders). They also need to be verified to make sure there are no leaks and leaching fields are functional. [“An important inspection can be made of your septic system when it is emptied. Here are some things to look for or at least ask the operator to examine: Check the baffles for corrosion or breakage; If water flows from the outlet back into the tank it is an indication that your field may be saturated; If water runs continuously into the tank, there is a leak in your plumbing (probably the toilet) and it could saturate your field; Ask the operator to estimate the level of solids. If the level is 60 cm (2 ft) or less, then your system is working very well; if you have a pre-filter installed at the outlet, this is the time to clean it.” Extracted from the Fall 2010 issue of Information Morin Heights (p. 5).]
By regulation, the first 15 m of shore line should be covered in bushes and trees to absorb nutrients. [ The Pépinière Rustique sells indigenous & wild plants (1614 Ch. du Village, St. Adolphe d’Howard, Tel: 819 327 2225, http://www.pepiniererustique.com/francais ).]
Avoid churning up the nutrient-rich sediments lying on the bottom of the lake.
Avoid fertilizers, especially on lawns and steep hills, and anywhere near the lake.
Use only phosphate-free detergents (both for dishwashers and washing machines).
Note on cyanobacteria
Currently, the lake does not seem to have abnormal or dangerous levels of cyanobacteria. We will continue to monitor colonies next season. Mme Tardif said the following changes are worth reporting immediately to Madeleine or Jérôme:
Dead frogs in the lake, because frogs are particularly sensitive to cyanobacteria.
An unusual or rapid increase in algae growth, or cloudy water resembling broccoli or pea soup.
Samples need to be tested by Notreau within 48 hours of collection.
On Sept 8, we were told that, about 10 days before, a green mass was seen floating on part of Drury Bay. We checked for signs of algae colonies in Long Bay and along the north shore of Lake Anne, including Three-Pine Bay, Seale Bay, around Pine-Tree Point, and along the Hugessen and Blachford shorelines. We found concentrations in shallow, calm waters (especially in bays), associated with organic material (see picture below). The highest concentration was in Long Bay, where the water was quite turbid.
On Sept 10, we took a sample from the bay between the Presqu’ile and Pine Tree Point to Notreau. Notreau’s microbiologist Guylaine Tardif found that our sample was mostly cyanobacteria, in a concentration of 3,300 cells/ml. She also gave us the following information:
[See, e.g., http://www.mddelcc.gouv.qc.ca/eau/eco_aqua/cyanobacteries/ ]
It is also normal to encounter concentrations of cyanobacteria in quiet bays with a high content of organic material (as we did). In this case, the cyanobacteria form roughly cylindrical colonies under water and anchor themselves to vegetation or dead trees (See picture above).
Mme Tardif added that there would be cause for concern if the concentration reaches 20,000 cells/ml; at this point, we would want to determine the reasons for the increase. (Cyanobacteria can start producing detectable toxins at 100,000 cells/ml, which is a much more serious situation.)
Currently, the lake does not seem to have abnormal or dangerous levels of cyanobacteria. We will continue to monitor colonies next season. Mme Tardif said the following changes are worth reporting immediately to Madeleine or Jérôme:
Dead frogs in the lake, because frogs are particularly sensitive to cyanobacteria.
An unusual or rapid increase in algae growth, or cloudy water resembling broccoli or pea soup.
UV filters and water systems
UV systems make lake water that contains coliforms potable. However, UV filters do not treat cyanobacteria toxins (if the concentration reaches 100,000 cell/ml, which is currently not the case). Sand filters and UV lights need to be changed regularly for the UV system to be effective. E,g,, UV lights should be changed after 12 months of use. After that, the intensity of UV may be insufficient for disinfection. This year, we were told that if the power is off for more than 3 hours, the pipes may become contaminated; the solution is to purge and treat the pipes and hot water tank with chlorine (household bleach).
Even with a UV system, if you drain your pipes in the winter, pipes and hot water tank need to be disinfected with chlorine when you put the water on in the spring. This year, we learned the following details:
Chlorine should stand in the pipes for a minimum of 5 hours.
After purging and treating the pipes after a non-conforming test, Notreau recommends waiting at least two weeks before retesting tap water, because residual chlorine can stay in the pipes and skew the results.
Water-Testing Details for 2015
Method
Samples were taken on Saturday, Aug 8, between 10 a.m. and noon. Nine sites were tested for fecal coliforms, colour, turbidity, pH, and phosphorus. The samples were taken 10 m from shore. (See map at the end of this report.) The approximate locations are:
Near Hunt’s point
In front of the Drury Estate
In Seale Bay
Near the mouth of Long (a.k.a. Boathouse/Wood’s) Bay
In front of Nancy Savage
In front of Guy Biron
Between Kenneth and Kathleen Hugessen
Between Reed Drury and Sally McDougall
At the end of the bay behind Green Mountain
We also tested three sites far from the shore for chlorophyll-A and dissolved organic compounds, both of which give information about the effect of rotting organic material on water quality. Taken together, levels of chlorophyll-A, dissolved organic compounds, and phosphorus tell us about the amount of nutrients in the lake.
Results
Fecal coliforms
Fecal counts are as high as last year, which was unusually high (This year, the average per sample is 9.3, as opposed to the cumulative average of 3.3 for all years).
At these levels, according to Public Health norms, untreated lake water is not safe to drink. However, it is in the “Excellent” range for swimming.
The following table shows the variation in fecal coliforms from year to year. High coliform counts seem to be associated with rains (sometimes heavy rains) just prior to testing day: e.g., 2003, 2006, 2010, 2013 and 2014. This year had a rainy summer, although there was no rain on Aug 6 or 7. (There was rain on Aug 1 and 2 and showers Aug 3 and 5.)
Phosphorus
Phosphorus concentration measures the amount of nutrients reaching the lake through runoff (This is linked to the risk for algae blooms). Official sources place the threshold for concern at 0.09 mg/l, but Richard Carignan, a U de M limnologist, draws the line at 0.06 mg/l. After four years of low levels, phosphorus concentrations are moderately high this year, though not yet a cause for concern. The diagram shows that we have had two previous spikes, in 2007 and 2009. [Phosphorus was not tested in 2008.]
Chlorophyll A and dissolved organic carbon
The levels of chlorophyll-A and dissolved organic compounds are based on three samples taken far from shore. [A = The opening of the bay past Green Mountain; B = The opening of Long Bay; C = The middle of the lake (approximately the latitude of the northern tip of the Island and the longitude of the eastern tip of the Presqu’île).]
The concentration of chlorophyll-A gives information about the abundance of phytoplankton (microscopic algae) and helps evaluate the level of eutrophication. Phytoplankton is more common if phosphorus levels are high, if the weather is hot, and if water moves slowly. The norms of the Ministry of the Environment indicate that a concentration below 10 µg/l is acceptable. This year, the tests average 1.95 µg/l, which is excellent.
The quantity of dissolved organic carbon is another factor in eutrophication (the process by which lakes gradually age, eventually leading to stagnation and increased algae blooms). This measure it tracks the effects of rotting vegetation and animals. Dissolved organic compounds give a brown colour to water. The average for Lake Anne this year is relatively low at 3.96 mg/l. It has remained unchanged in the last three years.
Colour and Turbidity
Colour can be caused by natural minerals, vegetable matter, or other organic compounds [ For information on measuring colour, see http://www.ceaeq.gouv.qc.ca/methodes/pdf/MA103Col20.pdf ] There was a slow increase in colour until 2008, which then appeared to level off, but, in 2015, it is more than twice as high as last year.
Turbidity continues to be moderately high. Turbidity levels above 5 are not a problem for swimming, but untreated water at sites above the norm may not be potable (even without coliforms). The average turbidity level was 5.66, with 4 sites above the norm. We need to monitor this to see whether the trend is real.
pH
Water is acid below a pH of 7 and alkaline above that number. This year, the pH is 7.4. Overall, there is a trend towards slowly increasing alkalinity, although this year seems to be an exception.
Report by Jérôme Rousseau and Madeleine Palmer
