By Ruth Longoria

Islander Rita Moore spends much of her time working to improve the conditions for native plant and animal life around her Fern Hollow home. In addition to her duties as watershed steward and forest advisor for the Washington State University extension office and native plant steward for the Washington Native Plant Society, she practices what she preaches through those titles. Moore clears ivy from where it would otherwise choke out trees and plants. And, she adds mulch around plants to prevent soil erosion during frequent rains along the neighbors’ shared ravine. She also spends time educating children and adults about the importance of being good stewards of the land.

So, surrounded by what she has helped create as part of the Island’s most spectacular abundance of organic greenery, she was a bit surprised, and of course saddened, when her cat died last month. The veterinarian told her the animal had ingested some sort of neurotoxin.

A neurotoxin is defined as a toxic agent or substance that inhibits, damages or destroys the tissues of the nervous system. Effects of neurotoxins can include behavior changes, seizures or sometimes death. One example of a neurotoxin is lead. Others include diazinon and carbaryl, commonly used as lawn insecticide, and found in many Northwest streams and waterways, according to the Washington Toxics Coalition in Seattle.

There’s no question that neurotoxins are present in Island waterways. But, what those levels might be and if they are responsible for the deceased feline, are questions that can’t be readily answered. The cat drank regularly at a stream, which flows swiftly over ledges and under culverts and walkways through Moore’s homesite and many of the neighboring properties. But, there have been no other recently reported incidents of neurotoxin poisoning and the vet couldn’t tell Moore which neurotoxin was involved in the cat’s death.

“We don’t really know if the cat died from drinking stream water,” Moore said.

But it is a possibility, a possibility that brings to the forefront Moore’s concern of toxins in Island waters.

Every year, the City of Mercer Island contracts with King County to produce a report on water quality monitoring in five of the Island streams. The five streams monitored alternate each year, as certain streams are selected if there is a capital improvement project scheduled for nearby, said Patrick Yamashita, city engineer.

The tests and recommendations provided help the city conform to Environmental Protection Act standards for water quality, which is based on the water’s short-term effects on aquatic animals. The streams are monitored for chemicals, as well as for sediment, which could be a sign of erosion to the stream, Yamashita said. Although the yearly monitoring program is not required, Island streams are expected to meet the state “AA, Extraordinary” water quality standards, since the water drains into Lake Washington, according to the annual report. The reports take a while to be compiled and the most recent reports currently available through the city are from 2002.

However, Dr. Fran Solomon, senior ecologist for the King County Water and Land Resources Division, recently finished compiling the data for the 2003 reports, which she will share with the city later this month.

Moore has a copy of the 2001 report, which states that some neurotoxin levels — such as that of diazinon, a previously popular lawn insecticide — “exceeded the Environmental Protection Agency’s draft acute freshwater criteria for this insecticide in 10 of 38 samples.” But, beginning in the late 1990s, diazinon was phased out by many retailers because of its human health-risks. Diazinon was replaced in many markets by carbaryl, another toxic chemical, produced by Bayer CropScience, and sold under the label Sevin. Though diazinon has disappeared from store shelves in recent years, sales of carbaryl have eclipsed previous diazinon sales 10 times over, according to information provided by the Washington Toxics Coalition.

Erika Schreder, a staff scientist with Washington Toxics Coalition, said banning use of diazinon and some other toxic chemicals has been a good thing for salmon and people who eat fish, since the chemicals have been linked to cancer. But there are still concerns with other toxic chemicals, such as carboryl, replacing the banned ones. The Environmental Protection Agency completed a comment period in May and is currently looking at carbaryl as to whether or not it also should be banned, Shreder said.

The levels of diazinon are significantly reduced in the 2003 study, so much so that the chemical was only listed as above EPA standards in one of the five streams, on one of the three testing days. However, Solomon said, diazinon’s replacement, carbaryl is not one of the 17 herbicides and pesticide checked for in the 2003 study.

“Carbaryl is a different class of pesticide. There’s one test that can be run for all 17 of the other kinds,” she said. To test carbaryl would cost more money, but that test might be added in the future, if the city and the budget allow, she added.

Also present in Island streams, according to the 2001 annual report, was chlorpyrifos, which is allowed to be used in home termite applications through 2005. Solomon said that chlorpyrifos was not present in any of the Mercer Island streams or drainage basins tested in 2003. This supports popular opinion that levels of certain toxins dissipate from streams within a few years of being removed from public usage.

Yamashita said he’s not overly concerned about toxins in Mercer Island streams.

“The results we’ve had are fairly typical of urban storm water runoff,” he said. “There are some pollutants, but to date we haven’t found anything significantly higher than what is typical.”

If a high level of a chemical pollutant is found, efforts are made to identify the source of the contaminant in order to educate people and stop or reduce the chemical infiltration into the water. However, that can be difficult since many of the pollutants identified are those found in landscaping supplies, he said.

“If the source is common, you may never find it.”