Saturday 29 October 2016
Plants That Invade Our Waterbodies
The following is the text of a handout from the CRE Laurentides, kindness of Bryan.
A plant is considered exotic when it is found outside of its natural range. The newly colonized environment is often devoid of predators of this foreign plant. This factor, combined with other advantages linked to growth and reprodution, makes exotic plants feroicous competitors of indigenous plants, to the point where they become invasive.
Aquatic exotic invasive plants (AEIP) can represent a serious threat to the environment. They alter the compostiion of natural ecosystems and disturb local biodiversity. Their proliferation has negative repercussions on the economy and on society, mainly by reducing tourism and the development of cottages. Recreatonal activities such as fishing, canoeing and swimming can be limited by an infestation of AEIP. The multiplication of AEIP can also negatively affect the value of lakeshore properties.
Controlling and managing AEIP is difficult. Once in place, it is almost impossible to limit their propagation. That is why it is crucial to insure that they do not enter our lakes.
In Quebec, many species of AEIP are present and established at varying levels. These include:
European frog bit (Hydrocharis morsus-ranae)
yellow floating heart (Nymphoides peltata)
water chestnut (Trapa natans)
curly-leaf pondweed (Potamogeton crispus)
Eurasian water milfoil (Myriophyllum spicatum)
Further information can be found on the Web at: www.crelaurentides.org
Water Testing Results, 2016 (Summary)
The following is a summary of the extensive report compiled by Jerome Rousseau and Madeleine Palmer. The full report will be available soon on the lake Web site at www.lakeanneclub.com
Samples were collected on Saturday, August 13, 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.
Three sites far from shore were tested 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.
Furthermore, three sites were tested for cyanobacteria.
Fecal Coliforms
Fecal counts are 50% higher than 2014-2015, which were unusually high (This year, the average per sample is 13.8, as opposed to the cumulative average of 3.91 for all years).
High coliform counts can be associated with rains (sometimes heavy rains) just prior to testing day: 2016 was a rainy summer. Records indicate 29 mm of rain from 11 to 13 August, but the reason for the increase remains to be established.
According to Public Health norms, untreated lake water is not safe to drink. However, it is still in the “Excellent” range for swimming. Public health norms state that drinking water should have zero coliforms, whether fecal or otherwise. Our lake tests measure only fecal coliforms.
Household tests provide information about other coliforms. It is recommended that lake water be treated by boiling or with a UV filter system before drinking.
Phosphorus
Phosphorus concentration indicates the amount of nutrients reaching the lake through runoff (This is linked to the risk for algae blooms). After four years of low levels, phosphorus concentrations were moderately high last year, and again this year. If this persists, it will be a cause for concern.
Chlorophyll A and Dissolved Organic Carbon
The levels of chlorophyll-A and dissolved organic compounds are based on three samples taken far from shore. The concentration of chlorophyll-A indicates the abundance of phytoplankton (microscopic plants) which are more common if phosphorus levels are high, if the weather is hot, and if water moves slowly. This year, the tests average 2.52 µg/l, which is excellent (but higher than the cumulative average by 40%).
The quantity of dissolved organic carbon 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 3.8 mg/l. It has remained unchanged in the last four years.
Colour and Turbidity
Colour can be caused by natural minerals, vegetable matter, or other organic compounds. There was a slow increase in colour until 2008, when it appeared to level off. There was a spike in 2015, when it was more than twice as high as the previous years. This year, with a level of 29.4, it is higher than the cumulative average (24.2), but less than last year (41.3).
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). Last year, the average turbidity level was 5.66, with 4 sites above the norm. This year, it has gone down to 3.86, with no site above the norm.
pH
Water is acid below a pH of 7 and alkaline above that number. This year, the pH is 7.25. Overall, there is a trend towards slowly increasing alkalinity, except for the last two years.
Cyanobacteria
There were 3200, 1998, and 2111 cyanobacteria/ml at the three sites tested. These sites were chosen because they experience less water movement than the lake as a whole, therefore they are the kinds of areas in which cyanobacteria can proliferate. Results showed a low count that is not a cause for concern.
As mentioned previously, we took these samples in order to measure trends. The presence of cyanobacteria in a lake is normal. Problems arise when their density is too high, at which point they produce algae blooms.
The microbiologist said that said the following changes are worth reporting immediately (to Madeleine or Jérôme):
Conclusion
This year, three measures are higher than average: fecal coliforms, phosphorus, and colour. 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. It is too soon to say whether this is a trend, but, if these measures stay at these levels, this will be a cause for concern.
We have a healthy lake where we can swim safely. We will continue to monitor the health of the lake, so that we can be proactive.
What we can do to keep Lake Anne healthy
We can help maintain the health of our lake by following these guidelines:
Samples were collected on Saturday, August 13, 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.
Three sites far from shore were tested 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.
Furthermore, three sites were tested for cyanobacteria.
SUMMARY OF 2016 RESULTS
Fecal Coliforms
Fecal counts are 50% higher than 2014-2015, which were unusually high (This year, the average per sample is 13.8, as opposed to the cumulative average of 3.91 for all years).
High coliform counts can be associated with rains (sometimes heavy rains) just prior to testing day: 2016 was a rainy summer. Records indicate 29 mm of rain from 11 to 13 August, but the reason for the increase remains to be established.
According to Public Health norms, untreated lake water is not safe to drink. However, it is still in the “Excellent” range for swimming. Public health norms state that drinking water should have zero coliforms, whether fecal or otherwise. Our lake tests measure only fecal coliforms.
Household tests provide information about other coliforms. It is recommended that lake water be treated by boiling or with a UV filter system before drinking.
Phosphorus
Phosphorus concentration indicates the amount of nutrients reaching the lake through runoff (This is linked to the risk for algae blooms). After four years of low levels, phosphorus concentrations were moderately high last year, and again this year. If this persists, it will be a cause for concern.
Chlorophyll A and Dissolved Organic Carbon
The levels of chlorophyll-A and dissolved organic compounds are based on three samples taken far from shore. The concentration of chlorophyll-A indicates the abundance of phytoplankton (microscopic plants) which are more common if phosphorus levels are high, if the weather is hot, and if water moves slowly. This year, the tests average 2.52 µg/l, which is excellent (but higher than the cumulative average by 40%).
The quantity of dissolved organic carbon 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 3.8 mg/l. It has remained unchanged in the last four years.
Colour and Turbidity
Colour can be caused by natural minerals, vegetable matter, or other organic compounds. There was a slow increase in colour until 2008, when it appeared to level off. There was a spike in 2015, when it was more than twice as high as the previous years. This year, with a level of 29.4, it is higher than the cumulative average (24.2), but less than last year (41.3).
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). Last year, the average turbidity level was 5.66, with 4 sites above the norm. This year, it has gone down to 3.86, with no site above the norm.
pH
Water is acid below a pH of 7 and alkaline above that number. This year, the pH is 7.25. Overall, there is a trend towards slowly increasing alkalinity, except for the last two years.
Cyanobacteria
There were 3200, 1998, and 2111 cyanobacteria/ml at the three sites tested. These sites were chosen because they experience less water movement than the lake as a whole, therefore they are the kinds of areas in which cyanobacteria can proliferate. Results showed a low count that is not a cause for concern.
As mentioned previously, we took these samples in order to measure trends. The presence of cyanobacteria in a lake is normal. Problems arise when their density is too high, at which point they produce algae blooms.
The microbiologist said that 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 of cloudy water resembling broccoli or pea soup.
Conclusion
This year, three measures are higher than average: fecal coliforms, phosphorus, and colour. 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. It is too soon to say whether this is a trend, but, if these measures stay at these levels, this will be a cause for concern.
We have a healthy lake where we can swim safely. We will continue to monitor the health of the lake, so that we can be proactive.
What we can do to keep Lake Anne healthy
We can help maintain the health of our lake 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.
- By regulation, the first 15 m of shore line should be covered in bushes and trees to absorb nutrients. Lawns promote run-off which adds to the phosphate load in the lake. 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).
Lake Anne Club Web Site Now Live
William Wankly announces the following:
The Lake Anne Web site is open for use and comments. The URL is www.lakeanneclub.com
The site is protected by username and password, and accommodates different user roles such as:
The site is protected by username and password, and accommodates different user roles such as:
- general public
- authorised user
- family
- property owner
- shareholder
- author
- director
- administrator
Access to content is controlled on the basis of role.
In order to gain access, you will need to set up a site account with your chosen username and password. Access will be blocked until the administrator has vetted your account application. A number of people have attmepted to gain access since the site's inception, hence the need for administrator oversight of accounts.
Once the administrator has vetted the account setup and allocated the appropriate roles, you will be able to tour the site. It is pretty sparse at this stage, with test stuff scattered around, but it's a start.
Minutes, both draft (for directors only), and approved (for the rest of us), are displayed either under the Home menu item or the Books (Minute Book) menu item.
The Lake Anne Blog is referenced from the site and may eventually be included through an RSS feed.
Those with the Author role will be able to create books. Jill Johnson is working on a history of the lake. Jerome Rousseau's history, based upon the minutes of directors' meetings, is already on the site.
Andrew Martin-Hugessen has agreed to assist me in the administrator's role. This is a full-on volunteer project, so please bear this in mind when looking through what's there.
There is a forum section and comments can be made everywhere, so don't be shy. If you want to blog, there is a basic blogging function anyone can use.
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