Lake Rosalind Logo
Home News & Bulletins Resources Residents Guide Water Quality Committee Pictures History Contacts Links

2023-09-14 - September 2023 Water Quality Report

Water Quality Committee > 2023-09-14 - September 2023 Water Quality Report

Thanks to Rick Kalte for providing the following information regarding the lake water testing on July 31, 2023.

Algae ID – The Algae Id was the first lab to report on the samples – One from Marl Lake’s first lake (ML-1) and another sample from Rosalind’s second lake (LR-2).

The algae in both these lakes were quite different in type and numbers.

ML-1 -Marl Lakes first lake had 32,453 cells/mL in total for all phytoplankton in the lake.

This total was made up of 74.7% Blue-Green Algae(B-G) and 24.5% of Green Algae.

There was a new B-G Algae genus present that has never been in the lakes before (Aphanocapsa). it came in at a whooping 19,000 cells/mL !!

This new B-G algae type was present in both lakes but was much higher in ML-1. Searching out info on this B-G algae it was found that it is a very small bacteria and not much research has been done to date because of its size. There was some information that noted that Aphanocapsa is on the rise in many lakes and that some species did NOT produce toxins.

LR-2 - Lake Rosalind’s second lake had 14,309 cells/mL in total for all phytoplankton in the lake.

This total was made up of 85.4% B-G Algae and 12.4% of Green Algae.

The new B-G Algae genus was present (5200 cells/mL) but in much lower numbers than in ML-1

Toxin Results- The toxin results came in yesterday and were late due to the lab not sending them out and the new policy of having to wait an extra week if toxin values are greater than 5 μg/L.

All 4 lakes were sampled and the results are given below following the flow of water through the lakes starting with LR-2 (Lake Rosalind’s second lake) and ending with ML-2 (Marl Lake’s second lake)

LR-2 3.95 μg/L

LR-1 6.79 μg/L

ML-1 2.42 μg/L

ML-2 1.66 μg/L

For your reference, the NEW Canadian Recreational Standard for Microcystin Toxin is 10 μg/L (down from 20 μg/L). The Canadian DRINKING Water Standard remains at 1.5 μg/L.

Conclusions, Comments and Opinions- From the results taken on July 31st we can conclude that the new genus of B-G Algae (Aphanocapsa) showing up in our lakes is of a species that is not producing toxins or else the toxin level in ML-1 would have been way higher than LR-2. The reason for LR-2 being slightly higher is that it had higher numbers of the other B-G Algae that are known toxin producers.

The B-G Algae known as Aphanocapsa is very small and is known as a Picoplankton whereas the other B-G Algae (Microcystis, Anaebaena) are known as Microplankton. The prefix “Pico “is one million times smaller than “Micro”.

We know from past years that the use of Biochar bags has brought down the toxins in the lakes. This year on Marl Lake the 12 new bags distributed along with the older bags seems to have been a good choice of location so far looking at this set of toxin results. Lake Rosalind will have to be looked at more closely with respect to Biochar. We know that last year all the lakes were very close with toxin numbers when the number of Biochar bags was raised in Rosalind.

The test results show all lakes were safe for recreation back on July 31 but we know that B-G algae is still present and all residents have to be vigilant about observing their water fronts for B-G Algae scums. These scums are very prevalent along some shores especially after calm nights or during calm days.

The good news is that the most recent mycrocystin tests show that Lake Rosalind 1 went down from the July 31st reading of 6.79 μg/L to 5.01 μg/L on the August 21st sample.