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Monitoring lake quality is ‘best volunteer job in town’
A flat boat pulls away from a dock on Solana Bay at 8:30 a.m. every Wednesday.
“We like to think of it as the best volunteer job in town,” says Brian Faltinson, president of the Osoyoos Lake Water Quality Society (OLWQS).
He’s joined by two other members of the society – Bryan Holgate, the vice president, and John Gates. They are on their weekly mission to monitor the health of Osoyoos Lake at a number of locations that are the same each week.
Each week they report their measurements to the Ministry of Environment where the data is compiled along with statistics from elsewhere in the province. Only in extreme weather do they stay ashore.
Holgate is the captain this week, guiding the boat through the south basin of Osoyoos Lake, between the markers in the channel at Haynes Point and towards the U.S. border.
Volunteers rotate positions each week so they can keep up all their skills.
Gates sits with a binder, ready to record the statistics they gather.
They locate the spot for the first set of measurements by eyeballing landmarks on both shores. To the west is a border marker and the centre of the customs station. To the east a dirt lane delineates the boundary between crops growing in Canada and a field of different crops in the United States.
Using a depth finder, Holgate fine-tunes the position of the boat.
The men do not measure coliform, bacteria or chemical composition of the water, indicators of pollution in the lake.
They do measure temperatures and dissolved oxygen at different depths as well as turbidity (clarity) of the water and pH or acidity. Water is sampled at five different locations and at various depths.
“Oxygen certainly is important for the health of fish in the lake and clarity gives us an idea of whether things are coming into the water and causing it to go unclear,” says Faltinson. “If the water is very turbid, we might inform some other agency to check on why it’s going that way, because if it’s happening suddenly then we want to do something about it.”
All three men and others in the society are committed to the environment. Currently there are about 15 volunteers, but the number fluctuates as members leave periodically for elsewhere.
On a typical outing there are three or four volunteers aboard. The readings are conducted from June to October.
“We make a point of having a few laughs while we’re going between sites,” says Faltinson. “While we’re at the sites we’re quite busy taking readings, but the crews are generally a good-spirited bunch.”
At our first stop on the U.S. border, Holgate lowers an instrument into the water at the end of a spooled rope. This measures temperature and dissolved oxygen.
The readings tell a story that explains the challenges faced by migrating sockeye salmon. At the surface, where there is a lot of oxygen, the temperature is 25 degrees Celsius, which is too warm for the fish.
At a depth of 10 metres, the temperature is a more salmon-friendly 17 degrees, but the oxygen concentration at 1.3 milligrams per litre is far below the 8 to 10 mg/L that the salmon want.
The fish must trade temperature for oxygen as they make their way through the relatively shallow waters of the south basin.
Another striking figure is how much less oxygen there is when you sample two metres lower at a depth of 12 metres. The oxygen drops to less than half at 0.56 mg/L – far too low for any fish to survive.
The measure of turbidity is done with a Secchi disk, a simple device named after its 19th century Italian inventor Angelo Secchi.
It’s a disk marked with black and white pie slices that is lowered into the water.
At a depth of four metres, Faltinson can no longer distinguish the black and white markings, so Gates records this figure.
Faltinson then uses another device that can collect a water sample at a specified depth. A metal ring is dropped along its rope to open the device and take the sample.
Water is collected from the surface and at a depth of 18 metres and Faltinson and Holgate measure its pH level or acidity.
A pH level of seven is considered neutral. Osoyoos Lake typically measures around eight, which is a touch on the alkaline side.
Measurements taken, we return to a second location north of Haynes Point. The process is repeated.
Most of the results are similar, but there are notable differences in dissolved oxygen levels. This, said Gates, could reflect the different currents in the lake.
The men drop off the Osoyoos Times reporter and then continue to their remaining three measurement locations.
They need additional volunteers, Faltinson says, noting that they lose members through attrition.
“I think once the word gets out people like to join because there’s so many people in town who care,” he said. “We tend to lose a few every year so it’s just nice to get a few new faces every year to fill those boots.”
Brian Faltinson can be reached at 250-485-2077.