The Beall well — Water District 19’s latest effort at water-supply development — is expected to go on line later this month, five years after the district decided to move forward on it and at nearly twice its projected costs.

It also won’t supply as much water as the district had hoped or as the state Department of Ecology allows. At 80 gallons per minute, the well will provide about 11 percent of the district’s summertime capacity, said Jeff Lakin, District 19’s manager. The district’s water right allows it to extract more than twice that amount — or 180 gallons per minute.

The well has proven costlier and more complex than the district had anticipated in large part because the water it produces contains nearly four times the arsenic allowed in domestic drinking supplies, Lakin said. Just recently, ammonia was also discovered in water samples.

As a result, the district is blending the well’s groundwater with water from Beall Creek, a standard approach for diluting arsenic, considered a carcinogen. The district will treat the ammonia with chlorine, Lakin said.

To those who have paid attention to District 19’s ongoing struggle to meet its pressing demand for water, the Beall well stands as a symbol — an example of just how tough and expensive it can be on Vashon to extract the resource for consumption and development.

“In perfect hindsight, it would have been a better outcome to spend the money somewhere else,” said Bob Powell, a commissioner for Water District 19, who came onto the board last year. “But I totally believe that it was the best decision that the people who made it could have made with the information they had at the time. There was no reason … to suspect it would have an arsenic and ammonia issue that would require extensive treatment.”

Frank Jackson, who recently stepped down as a commissioner, agreed. “It was a reasonable pursuit to provide more water, but it’s been almost as unlucky as the other wells in District 19.”

The arsenic has proven particularly troubling for some, who worry that it means District 19’s water quality is diminished by the discovery. The state’s maximum contaminant level for arsenic — a naturally occurring chemical found in many water supplies — is 10 parts per billion (PPB). The Beall well, before dilution, is at 39 PPB; after dilution, it’s at 6 PPB, Lakin said.

Jackson recalls how pleased the district’s commissioners felt after its engineers dug the well — at 560 feet, it’s considered a deep one — and finally hit water. “It would have been nice if it had been good water. The problem is that it’s not,” he said.

The arsenic levels, Jackson added, “are a concern. … I’m hoping that the mixing operation … always works.”

But Powell, who has researched the issue considerably, said he has made peace with the arsenic issue, in large part because the Beall well represents only a fraction of the water district’s overall supply. Some environmental advocates who study arsenic in drinking water supplies are pushing for tougher standards; they’ve been unsuccessful, Powell noted, in large part because the technology for removing arsenic — reverse osmosis — is expensive and uses up large quantities of water.

“It would be a crippling economic burden around much of the country,” he said

The issue, Powell added, is one of balance and cost. “It’s a long-term concern and has to be balanced with everything else,” he said.

Water District 19 is Vashon’s largest water purveyor, providing the resource to all of Vashon town, as well as to residents north of town and as far south as Maury Island. But water extraction has proven difficult for the district, and for more than a decade, the agency has had a moratorium for new water shares in place. The district’s waiting list for new shares now contains some 300 requests.

The Beall well is the district’s fifth and latest. Its development was slated to cost around $250,000, Lakin said, but it’s expected to log in at $400,000. “For 80 gallons per minute, it’s a ton of money,” he said.

From the get-go, the Beall well has been contentious and difficult. The water right for the well came from the Beall Greenhouse Co., which sold the right to Water District 19 more than 20 years ago for a nominal price. When the district decided to use the right to develop a well, some Islanders — concerned about the impact the well could have on Beall Creek — objected, claiming the right was too old to be valid. They formed an organization called Protect Our Water and filed a lawsuit.

Ultimately, the district and the citizens’ group settled in 2005, agreeing that the utility could develop a smaller well than the initial water right allowed, recalled John Arum, a lawyer and Islander who represented Protect Our Water.

The well is now weeks away from going online, Lakin said. All that’s left is for the state Department of Health to sign off on the utility’s operating plan; the agency already approved a pilot study.

Meanwhile, he noted, the utility has achieved some success in its efforts to meet ongoing demand — but not through well development.

Over the last few years, in large part because of the commissioners’ efforts at encouraging conservation measures, Lakin believes, demand for water from District 19 has declined. Peak demand for water has dropped around 10 to 20 million gallons per year over the last seven years, he said, from a high of around 130 million gallons to a low of 110 million.

“There’s definitely a trend downward,” he said.

Had the district invested $400,000 in conservation measures rather than another well, the results may have been more fruitful, Powell added.

“There’s no finger-pointing or perception of blame,” he said. “But I think there is a consensus that the district needs to be extremely selective in choosing future capital projects.”