2009 restoration project clears wood waste from nearshore area on Blakely Island
Before it was restored to the coastal beauty it is today, Thatcher Bay was once polluted with so much wood waste that it was dubbed “Sawdust Beach” by visitors and locals on Blakely Island of the San Juan Islands.
This nickname came from the wood waste that engulfed the bay from the old sawmill that sat over Thatcher Bay on a pier from 1879 to 1942. Over the course of decades, the sawdust collected formed a four-foot-thick layer on the bottom of the vein in the intertidal area. This layer of contaminated sediment became toxic enough to be uninhabitable and lethal for marine organisms.
Wood waste cannot decompose in saltwater, and the types of fungi needed to break it down wood cannot survive there. Thus, the wood waste pollution in Thatcher Bay would never resolve itself naturally.
This unfortunate circumstance was noticed in 2009 by Joel Breems, a then-graduate student from the University of Washington, who was seeking a restoration project for his graduate thesis in marine biology.
Breems writes in his thesis, “Wood-waste in Thatcher Bay [contributed] to elevated levels of total organic composition (TOC) of the sediment. Increased TOC favors anaerobic respiration in marine sediments and sulfide, a toxic by-product of this process, was found at levels as high as 17.5 mg L-1 in Thatcher Bay. The Thatcher Bay sulfide levels are several orders of magnitude higher than those known to impact benthic invertebrates.”
The nearshore habitats of the San Juan Islands are necessary for terrestrial and marine organisms, and the degradation of the area surrounding Thatcher Bay convinced Breems that a restoration and conservation effort was of paramount importance.
To accomplish this, Breems approached Dr. Sandy Wyllie-Echeverria, a research scientist at the University of Washington (since 1991) stationed at the Friday Harbor Laboratories in the San Juan Islands (since 2005) for help and guidance in setting up and conducting the project.
“Joel got in touch with me and said he wanted to do his master’s degree,” Wyllie-Echeverria said. “We decided on the project [and] my role was to encourage him to use certain techniques and methods to get some idea of how much wood waste there was and what would be the best way to dispose of it. It was a discussion as to whether it needed to be disposed at sea or on land.”
Dr. Tim Nelson, a biology professor Breems studied under at Seattle Pacific University, recalled that Breems worked for the Skagit Fisheries Enhancement Group during this time. While working with SFEG, Breems began organizing the project and secured its funding from the Salmon Recovery Funding Board.
“[Breems] went off to work in the Peace Corps for a couple of years, came back and worked for [SFEG] and got them interested in trying to do a restoration of the bay,” Nelson said. “They were set up with funding from state and federal agencies, so they came in and dredged out as much of the sawdust as they could and then brought in clean fill to bury whatever else was left.”
One of the companies contracted by SFEG to assist in the restoration was Anchor QEA, which offers environmental and ecological services for businesses. In this case, Anchor dispatched a field team led by Dr. David Gillingham, a kelp biologist, to monitor the turbidity (clarity or haziness caused by individual particles), pH (acidity or basicity) and dissolved oxygen (DO) levels of the bay’s ocean water.
“There’s a linear requirement that you can’t exceed the turbidity, pH or dissolved oxygen within an area designated when you do a project,” Gillingham said. “We had instrumentation that measured turbidity and pH and that measured everything compared to certain levels. If it exceeded them, we had to slow the operation down or stop the operation until the measurements came back in compliance.”
The purpose for these measurements came with the method of restoration Breems suggested: removing the approximate 11,600 cubic yards of wood waste and replacing it with layers of clean sand. Depositing large amounts of cap material (clean sediment, sand or gravel) can negatively impact coastal areas if improperly monitored.
To preserve the nearshore habitat and ensure their efforts resulted in healthier water, the conditions of the ocean water could not exceed a certain threshold measurement of pH, turbidity or DO.
“The remedy chosen was to place a layer of clean cap material to contain the contaminated sediment so it wasn’t available to the animals that lived in the habitat,” Gillingham said. “Ocean water itself has its normal pH, turbidity and DO and [at about] five parts per million, so if we go in there and measure 20 parts per million before they start, then their effect has to be less than five parts per million over that background.”
Gillingham explained his role was most important to confirm the safety of the bay’s marine life.
“One of the reasons why you don’t want the turbidity to go up is it makes that dissolved oxygen in water unavailable to animals,” Gillingham said. “Thatcher Bay is a nursery environment for small fish, and if they can’t breathe in the water that they’re living in, they won’t reproduce there.”
Thatcher Bay would remain under study for another five years before the removal and replacement of contaminated sediment began in November of 2014. The restoration was completed in December of 2014.
A 2015 post-project monitoring report sent to SFEG by the University of Washington’s Thomas Peterson found that the bay was slowly healing and becoming more hospitable to marine life.
“Analysis of grain size results show that sediment obtained from the project site, 10 months after completion of the work, are predominantly sand at 99.2%,” Peterson wrote. “Previous results from 2009 sampling data indicated that the sediment that was to be dredged was predominantly silt at 83.7% overall. Total volatile solids were also lowered from 12.9% in 2009 samples to 5.4%.”
Although no evidence of forage fish spawning was found at the time, these results meant that the bay was within the parameters to host forage fish spawning, set by the Washington Department of Fish and Wildlife.
“The results demonstrate that the sediment at the site went from mostly silt to predominantly gravel and sand. The [WDFW] states that the preferred sediment attributes for surf smelt spawning are a sand and gravel mix where most of the sediment is between 1-7 mm in size,” Peterson wrote. “The restoration site may continue to provide suitable habitat for future spawning events, [fulfilling] one of the project’s objectives to improve forage fish habitat.”
Most importantly, Peterson’s report called for continued monitoring to certify the long-term progress and success of the restoration.
“Monitoring is a vital component of any comprehensive restoration project,” Peterson wrote. “The success of restoration work hinges on [whether] ecosystems can be altered to a desired condition, and whether … the alterations have produced the desired condition. The scientific uncertainties are what monitoring efforts try to better understand so that [future] endeavors can be improved upon.”
Nelson’s recent visits to Blakely Island show the success of this project, as he and others observe the quality of life and water in Thatcher Bay. According to Nelson, the water is significantly better than he had known before.
“We’ve seen seaweed starting to grow again. [Some] folks have a little oyster farm established out there now,” Nelson said. “In April, when I was up with a class, a crab fisherman said a buddy of theirs pulled 10,000 pounds of crab out of the bay. We didn’t see crab in Thatcher Bay before the restoration, so they definitely improved the water quality.”