The State Department of Ecology is assuring customers of the Sammamish Plateau Water and Sewer District that an infiltration of storm water is a common practice where groundwater is the drinking source. The information, in a June 13 letter, notes that the practice is used in Redmond and Spokane  in addition to Issaquah and Sammamish.

“Issaquah withdraws water from this same aquifer and also needs to protect its use as a water supply,” the letter states. “Issaquah previously operated the infiltration system, known as the Lower Reid Infiltration Gallery (LRIG), from 2002 to 2008. In 2007 the district, Issaquah, and Ecology met over the district’s concerns about the LRIG. In 2008, Issaquah agreed to stop discharge into the infiltration pipe and direct the treated storm water to the North Fork of Issaquah Creek while they completed water quality testing and a well assessment.”

The letter goes on to say that the system is and will be under tighter scrutiny than any other rainfall infiltration system in the state.

Ecology is still developing a proposed permit.

Larry Altose, media spokesman for the department, said the hot-button nature of the issue will mean a public hearing will be held in the future with the public given plenty of advance notice.

The controversy surrounds not only possible contaminants in the storm water, but the fact that the infiltration area is only 600-feet from the district’s well No. 9. The well hasn’t been used since 2009.

However, Jay Krauss with the district said previously that the water district plans to activate well No. 9 from Nov. 1 through April 30 because it has to shut down wells seven and eight for service.

Gerald Shervey, industrial unit supervisor with the Department of Ecology, said that the district’s statement that a majority of the customers’ water comes from its wells is “not exactly accurate.” The permit, if issued, will be a state waste discharge permit, rather than an “industrial” permit, which the district called it in its letter.

“State waste discharge permits reflect our state’s authority over all water disposal, including storm water into the ground. Ecology required Issaquah to apply for permit coverage on the application with title, ‘Industrial Discharge to Ground’ because it was the closest match for this unique situation,” the letter states. “Ecology has no standard application for municipal storm water discharge to ground by underground pipes because permits are normally not required.”

Shervey said it is Ecology’s job to protect groundwater regardless of proximity to a well.

When asked about the potential of 1,200 new units in the property owned by Lakeside Development, he said the developer is responsible for storm water runoff during construction and whoever controls the development must adhere to King County surface water design standards.

Before the Issaquah Highlands was developed, Shervey said, it was all trees. One of the agreements when the Highlands was built was that an infiltration system be installed to replace the natural infiltration the trees provided.

“The aquifer is very important to the health of Issaquah Creek, the North Fork especially,” Shervey said. “So it’s very important the water be clean before it flows into the North Fork.”

He said by allowing injection, they expect to see a greater protection of water quality, which will be monitored. A surge from a storm, directly into the North Fork of Issaquah Creek would be worse.

He said it was beyond the scope of the Department of Ecology to comment on any perceived political issues between the district and the city of Issaquah.