The findings of an independent study of water and soil around the Mayflower oil spill reveal one remaining area of concern previously thought to be clear, but do confirm what previous tests have indicated — the majority of Lake Conway contains safe lake water and livable conditions.
Researchers from Arkansas State University recently finished several weeks worth of ecotoxicology tests, underwritten by the Log Cabin Democrat, on samples from Lake Conway and the Mayflower community following the ExxonMobil oil spill.
In the months since the Pegasus Pipeline ruptured, spilling more than 3,500 barrels of oil into the Northwoods subdivision of Mayflower, official testing done around Mayflower has shown healthy air and water. Independent testing should ease some concerns, but some environmental issues may remain in the cove where intense work subsided recently.
Early one summer morning 10 weeks after the Mayflower oil spill, two researchers got in a boat and launched off a dock into Lake Conway. The lake is known for its fishing, but the women on the boat were not fishing for bass or catfish; they were fishing for answers.
Black oil seeped out of its confines into a quiet Mayflower neighborhood March 29, running down the street and threatening Lake Conway. Homes were evacuated, the cove next to I-40 was dredged and health concerns surfaced among the citizens of Mayflower.
Six sets of samples were gathered by the researchers the morning of June 7. Three came from the lake, one came from the cove, one came from the drainage ditch across from the Northwoods subdivision and the last came from the ditch next to a Subway restaurant off of AR-365 S.
After a morning of gathering water and sediment samples from the lake, the cove and the community, Dr. Jennifer Bouldin and Molly Kennon traveled back to Jonesboro, eager to start their research.
Bouldin serves as the director of the Ecotoxicology Research Facility and associate professor of environmental studies at Arkansas State University. Kennon is a graduate student under Bouldin.
What the testing means for Mayflower
With two out of the three tests indicating anomalies with samples taken from the cove, Bouldin said contaminants in the area are not acutely toxic, but it would be wise to keep an eye on the site.
"I think that would be something worth looking at again at a later date," she said. "There’s definitely still a little something left at the site."
The cove, which was dredged as part of the Unified Command’s cleanup effort, has already moved from emergency response to remediation. At that point, control of the site is transferred from the Unified Command directly to the Arkansas Department of Environmental Quality.
The remediation of the cove included a hydromarsh recommended by the Arkansas Game and Fish Commission that put flowers and grasses back in the dredged area.
Bouldin noted the area may remediate itself and that — according to their testing — the contaminants are mostly contained to the cove area.
As for the lake itself, Bouldin said the Ecotoxicology Research Facility’s findings did not raise concern with her. The test results could be attributed to dilution of the water.
"I think it was so diluted by the time it got to the lake that it got a lot of it dredged out of there," she said. "I don’t think the water’s that bad in the lake."
The WET Testing
The Ecotoxicology Research Facility is an Environmental Protection Agency certified facility that offers several services including Whole Effluent Toxicity — or WET — testing.
WET tests are generally used to measure wastewater’s effects on organisms’ ability to survive, grow and reproduce. Bouldin and Kennon used two of these tests used to indicate chronic toxicity to see if the organisms would survive and flourish in the water collected from Mayflower.
Bouldin and Kennon used two independent seven-day EPA-recommended WET methods to test the water. One involved Ceriodaphnia dubia, a small freshwater organism that is a species of water flea. During the seven day test, researchers compared the survival and reproduction of the C. dubia in water from each of the six sites to the survival and reproduction of a control water.
The other test involved Pimephales promelas, or fathead minnows, cultivated in the lab. Instead of measuring survival and reproduction as they were doing with the C. dubia, the researchers measured survival and growth in the fathead minnows. Again, fathead minnows in the water from the six sites were compared to fathead minnows in a control water.
After the seven days, Bouldin reported the only significant difference in the tests was with the reproduction in C. dubia tested in water from the cove. Reproduction was lower than the control in those samples.
There were no significant differences between the site water and the control with the fathead minnows.
"The C. dubia and the fathead minnows are sensitive to different things," Bouldin said. "With these types of contaminants, the C. dubia would be the more sensitive species. You always do both just in case there’s something else there as well."
The sediment toxicity testing
Bouldin and Kennon also tested sediment from each of the six sites. These tests involved EPA-recognized Chironomid, or bloodworms, that ingest the sediment. The sediment tests took 21 days instead of seven days.
Like with the fathead minnows, researchers compared the survival and growth of the worms from each sample of Mayflower sediment to the survival and growth of the worms in a control sediment.
"If there is any contaminants in the sediment, it will either impair their survival or their growth depending on how bad it is," Bouldin said.
Results for the sediment tests showed similar results to the C. dubia — survival of the organisms was normal, but the worms in the sediment from the cove did have significant decrease in growth, Bouldin said.
In response to news that independent researchers have expressed concern about the cove, ExxonMobil spokesman Aaron Stryk emailed this statement:
"We’re not able to comment on these test results because we have not had the opportunity to review them. That said, the Unified Command has stated before that it is willing to review credible data from independent parties should that data be made available to ADEQ.
"Please note that all of our data is available for review on the ADEQ website, including that taken and analyzed by ADEQ. We will continue to remediate the affected areas under the direction of the ADEQ."