British Columbia's dry summer is creating alarmingly low river levels throughout the province, a problem that could endanger fish populations in some regions, the provincial government warned Tuesday.
The Ministry of Environment is encouraging British Columbians to conserve water and create drought-management plans to mitigate the record low water levels in streams across B.C.
According to its website, the Peace, Liard and Skeena regions have been classified as Drought Level 3, which would indicate "concern for fish and water supplies, unless significant rainfall occurs." Some areas in those regions only received a quarter of the amount of rainfall expected for this time of year.
The Lower Mainland also received only two-thirds of its usual rainfall. This could put salmon at risk, according to Diana Allen, a professor of earth sciences at Simon Fraser University. "The whole province is really suffering quite significantly from this dry spell," Dr. Allen said.
In late summer, rivers in the province go through "low flow" periods after the snow pack has completely melted and glacier water stops running. Salmon spawn during this period.
Dry periods could affect salmon spawning in two ways: by creating water levels that are too low for fish to swim in, or by heating waters up, which deteriorates fish habitat.
"It's the heat that is actually more critical sometimes than the low flows," Dr. Allen said. Salmon are a greater concern than other species of fish. "I don' t want to say they're picky, but it's a very narrow range they're comfortable in," she said.
"We are on the edge of the temperature at which salmon can get into real trouble," said John Reynolds, a professor of ecology at Simon Fraser. So far this year, salmon have been counted in numbers higher than originally forecasted - a positive sign, Dr. Reynolds said. But the lower, warmer rivers, especially the Fraser, may negatively offset those gains.
"Climate change is happening, and I'm afraid that the future of the Fraser is a much warmer one," he said.
The upper and middle Fraser River areas are at Drought Level 2, and expected to stay that way for the rest of the summer unless significant rainfall occurs. The ministry website is urging "voluntary conservation, as well as planning at the local level using tools such as drought management plans."
In the northeastern part of the province, species other than salmon are a concern. There, "we have many species of freshwater fish that are found nowhere else in British Columbia," Dr. Reynolds said.
On Vancouver Island, most river levels are at or slightly below average, exceptions for the Tsolum River, which is well below average, and Tofino Creek, which is slightly below average, the ministry reported.