UPDATE 2:35 pm, Thurs Aug 8, 2019: Risk advisory for Sandy Lake lifted
“When an algae bloom is observed, a risk advisory is issued and initial testing is done to determine whether the algae bloom is toxin producing. If the algae bloom is not toxin producing, the risk advisory will be lifted and no further testing is required.
“If the algae bloom is toxin producing, further testing will be carried out and the risk advisory will remain in effect until blooms have disappeared and post-bloom test results indicate water is within safe limits.”
and earlier, from info forwarded by Councillor Tim Outhit, received from Cemeron Deacoff (Water Resources Specialist, Planning and Decelopment, HRM):
We received the lab results late yesterday afternoon that the specimens identified in the lab were principally diatoms (a form of algae), with trace amounts of one species of cyanobacteria that does not produce any toxins. Correspondingly, staff (i.e., P&D Acting Director Eric Lucic) has approved lifting the PSA. Corporate Communications is now drafting that PSA…
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Original post (Aug 6, 2019)
Received this afternoon:
Public Service Announcement
Risk advisory in effect for Sandy Lake due to possible blue-green algae bloom
Wednesday, Aug. 7, 2019 (Halifax, NS) – The Halifax Regional Municipality is advising residents that due to the presence of a possible blue-green algae bloom, a risk advisory is in effect for Sandy Lake in Bedford. Residents are encouraged to avoid swimming in the lake until further notice.
Sandy Lake Beach, which is a supervised beach, will also be closed to swimming until further notice.
Blue-green algae (cyanobacteria) is naturally occurring in freshwater environments and may become visible when weather conditions are calm. These organisms can multiply rapidly during the summer, leading to extensive growth called a bloom. Some types of blue-green algae produce toxins during blooms and when these blooms decay, the toxins may be released into the water, posing a risk to people and pets.
Lake users are encouraged to take the following precautions:
· Avoid water contact. If contact occurs, wash with tap water as soon as possible.
· Do not swim or wade (or allow your pets to swim or wade) in any areas where blue-green algae is visible or in areas where a risk advisory has been issued.
· Avoid consuming water from this lake.
· Avoid consuming fish that has come from this lake.
People who come in contact with blue-green algae or who ingest water containing blue-green algae may experience skin irritation, rash, sore throat, sore red eyes, swollen lips, fever, nausea and vomiting and/or diarrhea. Children and immune-compromised individuals are at a higher risk. If you have these symptoms, you are advised to seek medical assistance.
Risk advisories are based on a number of factors, including test results as well as information regarding the current life-cycle phase of algae blooms. As algae blooms die and decay, toxins are released. Unsafe toxin levels can remain in the water even after the bloom is gone.
Once blooms have disappeared and post-bloom test results have been received, an update will be provided. If test results indicate water is within safe limits and no blooms can be visually observed, the risk advisory will be lifted.
To learn more about algae blooms, visit https://www.halifax.ca/about-halifax/energy-environment/harmful-algae-blooms.
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If it is due to BGA (blue green algae, cyanobacteria), it may indeed have been related to the rapidly falling water levels – that needs to be investigated.
It would also be helpful to see the evidence that this particular problem is due to blue-green algae (cyanobacteria).
If the evidence is not firm, what other steps are being taken to ID the cause?