State officials mailed letters to 200 Vashon property owners last week seeking permission to sample their soils — another step in the state’s ambitious effort to clean up yards and gardens tainted by Tacoma’s copper smelter decades ago.

The letters went to property owners on Maury Island and the southern half of Vashon Island, areas officials believe could have been affected by the smelter’s arsenic- and lead-laced plume. The first 50 property owners to respond will get their soil sampled.

The state’s goal is to use residential sampling to provide more information about the extent and location of contamination, so as to refine and improve a map it created last year showing the general outlines of the plume.

All of Maury, the southern third of Vashon, Burton and the Burton Peninsula are currently within what the state considers the “high zone.” But that high zone for contamination will likely look different, said Hannah Aoyagi, a project planner with the Department of Ecology’s Tacoma Smelter Plume project, once the state creates a more detailed and refined map, taking into account topography, proximity to the smelter and the many soil tests the state hopes to conduct within the high zone.

“We’re planning to use this (new) map to get a much better sense of where we might have to clean up,” she said.

The current map, she added, “is a rough estimate.” The new one, developed by a geo-statistician using various factors and considerably more data, “will show the highest probabilities for contamination,” she said.

The state announced plans last fall to undertake a far-reaching sampling and remediation program in neighborhoods that scientists believe were most affected by Asarco, a Ruston-based copper smelter that produced a toxic plume some 1,000 square miles in size before it closed in 1986. Highest on the list are neighborhoods in Ruston, north Tacoma, University Place, Maury Island and southern Vashon Island.

State funding for the massive cleanup comes from a settlement Asarco made when it filed for bankruptcy in 2005. The state received $188 million in settlement funds and expects to spend about $64 million of that on its yard cleanup program, the centerpiece of its Tacoma Smelter Plume project.

The state is targeting only those properties where tests show that arsenic levels are 100 parts per million (ppm), or five times what the state considers a level in need of cleanup, and lead levels are 500 ppm. “We’re not talking about insignificant amounts of contamination,” Aoyagi said.

In June, the state completed its final action plan for the Tacoma Smelter Plume program, targeting residential cleanup within the plume’s high zone as one of its key strategies, along with ongoing outreach and education and a soil safety program.

But some elements of the residential cleanup plan are still being determined. And once the new map is finalized and details of the residential cleanup program are in place, state officials will return to Vashon for another round of public comment.

“It’s an iterative process,” Aoyagi said.

On Vashon, meanwhile, some who received the state’s letter last week, asking for permission to come onto their property to sample the soil, quickly filled out the forms and sent them back to the state.

“We don’t have anything to hide, and we might have something to gain,” said Sue Gardner, who lives with her husband Jim on southern Vashon Island, near Camp Sealth.

“I’ve always been curious to know the level of arsenic here,” she said, adding, “It seemed like a fairly benign request.”

Hilary Emmer, who lives on Maury, agreed. “I already sent in the form. I think we should know what is really in our soil.”

But others said they don’t want state officials to come onto their property and test their soils, even if it’s only to refine a map.

Lou Engels, who lives just north of Portage and received a request from the state, said he won’t give officials the green light. He’s lived at his home on Highland Avenue for nearly 40 years, he said.

“It’s not creating a problem,” he said of any potential arsenic in the soil. “Why turn it into one? I just really think there’s nothing to worry about.”

Jean Bosch, a real estate agent, said some on Vashon are worried about what the state’s cleanup program could mean for their homes’ resale values, as well as their obligations for disclosure when they decide to sell.

“We’re painting some people’s property orange (high zone) and some green on these maps, and it’s scary to people,” she said.

Bosch, like others, said she doesn’t know what high levels mean, nor has she seen any evidence that indicates high levels can harm someone, unless that person actually ingests a lot of dirt. If arsenic in the soil is truly a problem, “It seems sort of crass to be thinking about resale values,” she added. “But is it harmful? I don’t think we know.”

But Aoyagi said longterm or repeated exposure to soil laced with arsenic and lead are considered health hazards; children are most at risk because of their propensity to put dirty hands or objects in their mouths.

“Statistically, we know there’s a risk” from arsenic and lead exposure, she said. “Thousands of studies show that arsenic and lead are toxic to the human body, to animals and to the environment.”

The state has set the bar for contamination high — at 100 ppm for arsenic — because “at 100 parts per million, we feel that there’s a much more serious threat to human health,” she said.

State officials, she added, know that some people won’t want to get their soil tested this fall or participate in the cleanup program once the high zone is delineated because they don’t see a problem at their homes.

And indeed, the program is voluntary, she added. “Individuals can opt out,” she said.

But she hopes homeowners will consider the long-term implications of arsenic-laced soil, especially for future families who might live there.

“It’s not a health emergency,” she said. “But we are concerned about low-level exposure over time, especially for children.”