Contamination concerns taint future for Overdale water supply

December 8, 2009

By Warren Kagarise

Overdale Park residents — concerned for years about arsenic contamination in a well drilled to serve the community — are worried about how water will be supplied to the northwest Issaquah neighborhood in the future.

The problem: Contaminated and inadequate wells cause Overdale residents to rely on the Sammamish Plateau Water and Sewer District for service. Overdale has a private water system, but the Sammamish district supplies water to the community.

A well near East Lake Sammamish Parkway Southeast is contaminated with arsenic and manganese. The well cannot be used to supply drinking water unless the neighborhood water association installs a pricey treatment system to remove the metals.

Environmental Protection Agency arsenic standards prevent the water association from tapping into the supply from the well.

Residents said iron and manganese in the water cause unpleasant odor and taste. The metals also stain clothing and appliances. Many residents installed water softeners to combat the hard water.

A second well at another site in the neighborhood is no longer adequate to meet demand.

The private system supplies water to 139 households, both Overdale residents and nearby homeowners.

Overdale has relied on the water district to supply the neighborhood since late 2005. The association pays the Sammamish district about $30,000 per year for water.

But the Overdale customers exhausted the emergency need for water defined in the agreement with the water district. Now, homeowners face difficult decisions about where water will come from when customers turn on taps in the future.

Residents weighed several options — with tough choices and big price tags attached — last week. Overdale customers raised questions Dec. 3, when representatives from most of the 139 households supplied by the Overdale system flooded a standing-room-only Overdale Park Water Association meeting.

The gathering was rife with questions about contamination and what residents would do if emergencies plagued the system.

“I’m concerned if we have a major well break at 2 o’clock in the morning, where do we go? Who do we call?” longtime neighborhood resident Lynn Chambers said at a forum before the Dec. 3 water district meeting.

Options carry costs, risks

Overdale customers face several possible scenarios.

Residents could install a water treatment system and work to counteract the contamination in the lower well, in order to meet drinking water standards. Overdale customers could blend water from the wells with water from the Sammamish district to reach drinking water standards. Crews could drill the lower well deeper to search for better quality water.

Overdale could be absorbed into the Sammamish district, or the neighborhood could extend the existing arrangement. Questions linger about whether residents would be able to afford the existing arrangement in the future, or if the other options would prove viable.

Sammamish district official Ron Little suggested for residents to hire engineers to help make the decisions. Overdale customers have “a whole plateful of options,” Little said.

The private water system was installed in the 1950s when a developer broke ground on the neighborhood. The community remained part of unincorporated King County until voters approved the annexation of the neighborhood into Issaquah a decade ago.

Many customers near Overdale are Sammamish district customers. The district serves about 16,300 water customers and 10,100 sewer customers in parts of Issaquah, Sammamish and unincorporated King County.

Construction of the most recent lower well strained the association. Costs rose after the water association drilled a new well in 2004 to replace the original well. The initial well, drilled to 140 feet, was completed in 1963. The wells are located near the Overlake Center retail complex.

Cost could be deciding factor

After the association sunk more than $170,000 into the project, it discovered the arsenic level was too high to meet federal standards for drinking water. The manganese level was high, too, but manganese does not pose a health risk.

Arsenic, however, presents a long-term health risk. The poisonous element occurs naturally in the ground near the well. Arsenic-contaminated ground water has been connected to various cancers and other health problems.

EPA regulations for arsenic in drinking water allow 10 parts per billion; the arsenic level in the newest Overdale well is 11.64 parts per billion.

The water association could blend water from the contaminated well with water provided by the Sammamish district in order to produce drinking water with acceptable arsenic levels. The blending option would cost about $58,000 — cheaper than constructing a water treatment plant.

But how to lower the arsenic level in water drawn from the lower well poses another challenge. Chambers referenced the expense when she discussed available options. A breakdown of available options notes how the cost of a treatment system — about $200,000 — would be prohibitive.

“The economics of that study are: it’s expensive,” Chambers said.

Another well, known as the upper well, was completed about five decades ago. The well, along Southeast 53rd Street, is inadequate to serve modern-day demand. Residents said water from the 510-foot-deep upper well also smells and tastes unpleasant.

Although customers could sometimes be unaware of manganese in the water supply, other conditions provide distasteful reminders.

Bob James, northwest region manager for the Office of Drinking Water, part of the state Department of Health, illustrated the problem. Manganese emerges through faucets “when you have high velocity of water through the pipe, it can slough off and then, all of the sudden, you fill your glass, and it’s black,” James said.

Warren Kagarise: 392-6434, ext. 234, or Comment at

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