Lake Whatcom level dropping months ahead of schedule

Bill Evans, water treatment plant chief operator, stands next to a filtration tank at Bellingham’s water treatment plant on Wednesday, July 1. Bellingham draws its water from Lake Whatcom, where the water level is dropping faster than normal, but the city’s water supply isn’t expected to be affected.
Bill Evans, water treatment plant chief operator, stands next to a filtration tank at Bellingham’s water treatment plant on Wednesday, July 1. Bellingham draws its water from Lake Whatcom, where the water level is dropping faster than normal, but the city’s water supply isn’t expected to be affected. The Bellingham Herald

The level of Lake Whatcom is dropping months ahead of schedule and could continue that trend as warm weather remains in the forecast.

While the lake reservoir is not impacted by the nonexistent snowpack that is affecting rivers and streams statewide, hot June weather has caused water to evaporate from the lake faster than average, according to Eric Johnston, Bellingham’s assistant public works director.

As lake level drops, the flow into Whatcom Creek can diminish and start to impact fish habitat; residents around the lake can have problems getting water if the lake drops below their intakes; and boaters can find their docks sitting low in the water, Johnston said.

The lake serves as the drinking-water source for about half of Whatcom County’s residents. It typically drops about 4 inches per month due to evaporation during a typical wet, cool spring and dry summer, Johnston said. This year, the lake has already dropped to the level it typically reaches in September.

“Over the long term, as we get into September and October, we are concerned about the lake level getting lower than it has in years past,” Johnston said.

Bellingham broke or tied four daily high-temperature records during June, according to the National Weather Service. The average high temperature for the month was 73.6 degrees, well above the normal average high of 66.7 degrees.

Rainfall also was well below normal, 0.26 inch for the month, compared to 1.86 inches on average.

“We are keeping a very close eye on the amount of water that flows into the lake, and the reservoir level,” Johnston said.

In winter, the city keeps the lake level around 312 feet, to control flooding on Whatcom Creek, Johnston said. In the spring, the level is raised to about 314.5 feet. The levels are balanced as rainfall fills the reservoir and a dam controls water flowing out of the lake.

The current level is about 313.4 feet.

“There is no lower bound on the lake level, other than the ability to get water into private intakes and for habitat and fish in Whatcom Creek,” Johnston said. “The last time the lake was below 310 feet, we had private properties around the lake that are not city water customers with individual intakes that were no longer submerged, and we ran into recreational problems with boat docks sitting low.”

The lake could get down to about 308 feet before the intake for the city’s water treatment facility at Whatcom Falls Park might see changes in water flow, Johnston said, but Whatcom Creek could dwindle dramatically at that point.

“You get below 309 and we get concerned about Whatcom Creek having any water in it,” he said.

The city is currently editing its drought plan to make sure it balances residential and recreational demand on the lake with the reservoir levels, Johnston said. The city does not yet plan to implement mandatory water restrictions, other than advising customers to be conscious of their water use.

“We encourage people to be very aware of the water supply and encourage conservation measures. Use water in off-peak periods (early mornings, late evenings). If grass is already dead, you probably don’t need to water it,” Johnston said. “Just be aware that water is a precious resource and try to use it conservatively.”

Demand for water up recently, but overall is trending down

On June 25 and 27, Bellingham had its peak demand for water so far this year when city customers used 11.28 million gallons of water each day. On June 25 last year, the city used 10.33 million gallons.

However, those numbers need to be taken with a grain of salt, Johnston said. For example, on Feb. 5, 2014, the city used 14 million gallons.

“We’re up a little over last year, but it’s not out of the ordinary,” he said. “Historically, our demand is declining.”

In the late 1980s through 1995, the city used about 25 million gallons a day, on average, Johnston said. The population was about 58,000 in 1995, compared to about 82,500 now.

Despite the jump in population, the city’s water usage has continued to decline, largely due to changes in building code efficiency requirements and to more efficient appliances, such as toilets and shower heads, Johnston said. The average use has dropped from 100 gallons per person per day to about 60 gallons per person per day.

“Throughout the United States ... even though you’ve got a population increase, it’s pretty typical that the per-person consumption is dropping,” Johnston said.

Algae impacts

More commonly, the city feels negative impacts on the lake from algae blooms, which can clog filters and slow the process of treating water before it goes to customers, Johnston said.

This time last year, a nontoxic type of golden algae affected water for some Bellingham customers, who described the water as tasting or smelling “musty, earthy or dirty.”

The city has had problems in the past with elevated levels of algae, partly caused by phosphorous-laden runoff from developed areas. Algae clogged the city’s filtration system and reduced the water supply. In 2009, algae concentrations were so high the city had to impose mandatory watering restrictions to cope with a potential shortage.

Neither of those types of algae blooms have been a problem so far this year, Johnston said.

“There is always algae in the lake, and it affects our ability to produce water a bit, but to date we have no taste and odor concerns,” he said.

Algae has been growing in different parts of the lake this year, and has not been near the city’s water intake, as it was last season.

The city is in the midst of working on a pretreatment system for the water treatment facility that would help pull organic material, such as algae, out of the water before it reaches the filters. It would do so by using air to float the material to the top and skimmers to help remove it.

The project is estimated to cost $17.8 million, with construction expected to start in spring or summer 2016. To the city’s knowledge, it would be the first system in the state to use the technology to pretreat drinking water, rather than use it to treat wastewater.

Reach Samantha Wohlfeil at 360-715-2274 or samantha.wohlfeil@bellinghamherald.com.