BREMERTON — Timing may be everything when it comes to understanding how the waters of Hood Canal can turn deadly.
For years, researchers have understood that nitrogen from various sources triggers the growth of plankton and ultimately the decline of oxygen in the waterway.
Now, experts realize that knowing when nitrogen enters the canal may be as important as knowing the total amount of nitrogen from various sources, according to Jan Newton, lead scientist for the Hood Canal Dissolved Oxygen Program.
For example, researchers have determined that large amounts of nitrogen are produced by alder trees. But that nitrogen flows into Hood Canal mostly in the fall, when fading daylight hours and clouds reduce the production of plankton.
So alder trees appear to be less of a factor in the low-oxygen problem than septic systems, which release nitrogen through their drainfields all year long, Newton said.
A computer model of Hood Canal is up and running, and researchers are beginning to understand how the timing and location of nitrogen flows can make all the difference in the world. Many of the old assumptions about nitrogen sources are no longer valid, she said.
“When people try to figure things out based on incomplete analyses, they may jump to conclusions that are not borne out,” she said.
Researchers know large amounts of nitrogen flow into Hood Canal with seawater. But seawater, which tends to be saltier and heavier, creeps along the bottom of the canal. Without sunlight, the nitrogen in seawater cannot be taken up rapidly by the plankton, so seawater may not be as important as some people think, she said.
Preliminary findings from the computer runs should be ready in about two months, Newton said, and officials are planning for a public announcement in mid-June.
The computer model, under development for nearly three years, simulates all the major physical and biological processes taking place in Hood Canal. Sun, wind and water currents are among the physical factors that can be depicted in the computer model, which also describes the growth of plankton under various conditions.
The growth of plankton is a critical issue, but their decomposition by bacteria in deep water is what consumes the oxygen and turns the waters deadly.
A series of buoys continually monitor water and atmospheric conditions in various parts of Hood Canal. A fish kill in September of 2006 allowed the researchers to diagnose conditions before, during and after the event, which resulted in thousands of dead fish, shrimp and even wolf eels.
Two fish kills in 2003, as well as extremely low oxygen conditions in 2002 and 2004, have painted a picture of how fish can be trapped within an area of deadly, low-oxygen waters. Scientists have learned that winds out of the south bring low-oxygen waters up from the depths, leaving marine animals little or no time to escape.
Preliminary findings to be released in June will undergo peer review by numerous scientists before being finalized. Even then, the work will continue for another year or more as researchers explore various scenarios such as the effect of hypothetically removing every standard septic system in the Hood Canal region.
The amount of nitrogen coming in from the shoreline is far from uniform throughout Hood Canal, Newton said. “We’re finding there is a degree of variability in both time and space.”
The importance of those differences is being tested.
Dan Hannafious of the Hood Canal Salmon Enhancement Group, another scientific leader, said it is rewarding to see all the volunteer monitoring over the past few years put to good use.
“When you go out every week, even in the middle of winter when you are frozen, you wonder sometimes if it is worth it,” he said. “But it is great to see how much value the work has had for the program.”
Hannafious said he does not expect the scientists to make policy recommendations. But the Legislature, as well as state and federal agencies, may choose to take action based on the upcoming findings.
U.S. Rep. Norm Dicks, D-Wash., who has secured ongoing funding for the studies, said seeing the results will be “very satisfying” and should set the stage for work elsewhere in Puget Sound. He stressed that a full-scale scientific review is essential to ensuring the credibility of the program.
“We’re going to have something to talk about,” Dicks said. “We’ll have something on which to base some judgments. I’m hoping that we take what we learn in Hood Canal and … transfer that to other areas of Puget Sound.”
Talk to us
> Give us your news tips.
> Send us a letter to the editor.
> More Herald contact information.
