BELLINGHAM - The quality of Lake Whatcom water may have stabilized, but it will likely take decades to get the city's drinking water source back to near-pristine levels.
So says Robin Matthews, lead scientist on the team that conducts an annual study of the lake's water commissioned by the city. Tests of 2013 water samples show that levels of most-watched pollutants have been holding relatively steady for several years.
"It's not better, but it's not getting bad as fast," Matthews said. "That's a good thing."
Matthews is director of the Institute for Watershed Studies at Huxley College of the Environment, Western Washington University. Like most research scientists, she is cautious drawing conclusions from the data she collects. But she acknowledged that stabilization in the lake's pollution levels may reflect efforts by the city, Whatcom County and the Lake Whatcom Water and Sewer District to reverse years of damage caused by phosphorus-laden runoff.
"I can't go so far as to say it's because of any particular thing," she said of the stabilization trend reflected in the last few years of water tests. "It is exactly what I would hope to see, in response to the work that has been going on."
Because algae growth triggered by ongoing phosphorus pollution will be a problem in the lake for many years, she said the city is being prudent in planning construction of a multi-million-dollar prefiltration system to remove algae before lake water gets to the city's existing water treatment plant.
When summer sun and warmth trigger increased algae in the lake, the microscopic plants can clog the city's filtration system, reducing the amount of water available to the city. In the unusually sunny summer of 2009, the problem was serious enough to require emergency measures to reduce household water consumption.
Since then, voluntary conservation measures, such as reduced lawn-watering, have kept the city from crisis, but Matthews agrees with Public Works engineers that a prefiltration system is needed to make sure the city can always provide enough water volume for both household and business use and for fire suppression.
While the prefiltration system is still in an early planning stage, engineers acknowledge it will cost millions of dollars. Would that money perhaps be better spent on cleaning up the lake, instead of filtering out the problem? Matthews said it's not that simple.
"The fact is, they are completely separate issues," she said. "The city has to look at the short-term needs. ... It (the prefiltration plan) does not in any way remove the obligation to clean up Lake Whatcom.
"We could spend millions, and it's still going to take decades to clean up the lake. ... In the meantime, every single summer we hit up against this question: Are we going to have enough water?"
Matthews said she had a chance to test a small, trailer-mounted prefiltration unit last summer. She ran samples of algae-laden lake water through the unit and her tests showed removal of about 90 percent of the algae.
Besides helping to maintain the capacity of the water system, algae removal also makes the water more healthful. When algae combine with disinfectants the city must use, chemical reactions produce small amounts of carcinogenic trihalomethanes that are still in the water when it comes out the tap.
The trihalomethane in Bellingham water is still well below the risky level, Matthews said, but the concentrations have been slowly rising.
The state Department of Ecology has ordered the city and county to come up with a long-range plan for curbing the phosphorus that is a key nutrient for algae growth in the lake. In addition to gumming up the city water plant, the algae become food for bacteria that use up the dissolved oxygen in lake water, making parts of the lake uninhabitable for fish.
While long-range plans are being formulated and much remains to be done, some progress has been made. The city and county have installed systems aimed at removing phosphorus from runoff in some areas, and steps are being taken to reduce the volume of runoff that enters the lake.
Matthews said reducing the runoff volume may be the most sensible approach, because phosphorus is difficult to remove once it gets into runoff water.
The city has also taken a preventive approach by buying land in the lake watershed to keep it from being developed. Since that effort began, the city has purchased close to 1,800 acres, at a cost of $28.5 million. That money comes from surcharges on city water bills.