HomeMy Public PortalAbout2022_Report Card_Sherbrooke Lake_Water Quality MonitoringCoastal Action l 45 School Street, Suite 403 l Mahone Bay, Nova Scotia l B0J 2E0 l phone (902) 634-9977 l www.coastalaction.org
Sherbrooke Lake STEWARDSHIP Committee
Monitoring of Sherbrooke Lake’s water quality is led by the Sherbrooke
Lake Stewardship Committee (SLSC). This committee is comprised
of citizen representatives appointed by the Municipality of Chester,
and the Municipality of the District of Lunenburg, in addition to
a water quality expert, and officials from both Municipalities. The
group receives technical support from Coastal Action, who have been
monitoring water quality throughout the LaHave River Watershed since
2007. Both municipalities provide funding to support the program,
while trained property-owners around the lake conduct the monitoring
activities with support from Coastal Action.
Sherbrooke Lake Sampling
Water samples are collected from lake and stream sites bimonthly and
tested for total suspended solids, total nitrogen, total phosphorus, E.
coli, and chlorophyll-α. Additionally, seven streams around the lake are
tested after a large rain event to monitor water quality changes related
to high runoff events. Bottom sediment samples are also collected at
three lake sites and one river site, to assess the long-term accumulation
of nutrients and metals which can also influence the lake’s water
chemistry. In 2021, the Municipality of the District of Lunenburg
purchased a Total Algae Probe which was fixed to the YSI sampling
device used to obtain on-site water quality readings. This additional
probe measures Phycocyanin and Chlorophyll-α. Phycocyanin is a
pigment found in cyanobacteria, or blue-green algae, and provides an
estimate of total cyanobacteria production. Chlorophyll-α is a pigment
produced by all types of algae and provides an estimate of total algae
production.
How is Sherbrooke Lake's water quality?
Bacteria
All lake sites are consistently below Health Canada’s 400 CFU/100 mL
recreational limits for E. coli– the highest lake concentration was 2
CFU/100 mL, well below the threshold. Lake sites were consistently
lower than stream sites. Health Canada guidelines were also not
exceeded for stream samples, except one – 550 CFU/100 mL at Peter
Veinot Brook on December 1st, 2022. Associated with this exceedance,
and spikes in bacteria concentrations at other streams, was a large
rainfall event. A spike in bacteria after rainfall is common and was also
observed in last year’s 2021 Sherbrooke Lake data. Although it does not
appear to affect the lake quality, swimming in rivers should be avoided
for 24-hours after a rainfall event. Water from the lake and the rivers
should always be treated prior to consumption (i.e., bathing, washing,
drinking).
Nutrients
During the 2022 sampling season, nitrogen and phosphorus
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Figure 1: 2022 map of Sherbrooke sampling sites.
Sherbrooke Lake Sherbrooke Lake 20222022 Water Quality Report Card Water Quality Report Card
concentrations fell within their respective guidelines
for freshwater rivers and lakes; however, both nutrients
have the potential to spike during rainfall events. The
increase in nutrients comes from rain washing nutrients
into nearby waterbodies from surrounding sources,
including roads, lawns, gardens, manure, fertilizers, etc.
Currently, Sherbrooke Lake’s nutrient status is at the
low end for freshwater lakes. This is encouraging news,
but only through continued vigilance will that situation
continue in the face of increasing development and
alteration of the lake’s shoreline and surrounding
watershed. Nutrient inputs from human activities
should be minimized as much as possible.
Algal Blooms
One algae bloom was reported in 2022 at Sherbrooke
Lake, at the North-East section of the lake, along the
shoreline of Sherbrooke Forest. The bloom dissipated
before volunteers could sample it. All blooms should be
treated with caution. Blooms are caused by a complex
interaction of biological, chemical, atmospheric,
and hydrographic conditions; many of which are
uncontrollable. However, excessive nutrient inputs are
one of the most influential factors in promoting a bloom
and one of the most controllable.
Coastal Action l 45 School Street, Suite 403 l Mahone Bay, Nova Scotia l B0J 2E0 l phone (902) 634-9977 l www.coastalaction.org
22
Overall Lake Health
Overall, the 2022 sampling program indicates that Sherbrooke Lake is healthy but vulnerable to the same pressures as other lakes such
as climate change and development. Activities such as fertilizing lawns, removing shoreline vegetation, and improper management
of septic fields and greywater can all impact the lake’s water quality. A more detailed report on the 2022 sampling program is available
upon request from the Municipality of Chester and the Municipality of the District of Lunenburg.
Algal blooms are a natural part of lake ecology but can be enhanced in size and frequency if pollution sources add extra
nutrients into the environment. In a balanced ecosystem, algae and other organisms’ growth is limited by the availability of
nutrients; however, if nutrients become available in excess (both naturally through fall and spring turnover and sediment
resuspension, or from human-caused pollution), algal blooms can occur. Not all blooms are algae (i.e., pine tree pollen forms a
film on the water’s surface), and not all algae blooms are toxic. Blooms should be treated with caution and should be reported
with a photo to the Nova Scotia Environment Office in Bridgewater (902-543-4685).
Did you know?
Take Charge of your Environment!Limit your footprint with these at-home tips:
Vegetated Buffers
Leave a section of natural vegetation between any lawns and
the lake to filter runoff.
Pick Up Pet Waste
Put pet waste in its place: the garbage bin.
Fenced Livestock
Keep livestock out of the water with fences (provide livestock
with alternate sources of drinking water).
Manure Liners
Line manure piles to prevent bacteria and nutrients from
leaching into adjacent waterways.
Straight Pipes
Replace illegal straight pipes with septic systems and
keep your systems properly maintained.
Fertilizing Before Rain
Avoid fertilizing your lawn before a storm, as excess
nutrients will be washed into nearby waterways.
Dish Soaps With Phosphate
Avoid using dish soaps with phosphates, as the nutrients
can cause harmful algal blooms in the water.
Try this Avoid this
Coastal Action is a charitable organization on the south shore of Nova Scotia that believes in
safeguarding a healthy environment for future generations. For over 25 years, our goal has been to
promote the restoration and conservation of our environment through research, education, action,
and community engagement. We work in five core areas: Watersheds & Water Quality, Species at Risk
& Biodiversity, Climate Change, Environmental Education, and Coastal & Marine.