DARRINGTON — Last week a rash of equipment thefts was discovered from stream monitoring sites in three counties.

The thieves targeted stream gauges in Snohomish, Skagit and Whatcom counties. The devices are used to monitor stream flow, water temperature and sedimentation.

The gauges are in locked metal boxes often mounted on or under bridges on creeks and rivers, or sometimes on the banks. At all of the locations hit, the thieves broke the locks on the gauge housings and removed batteries, said Darrin Miller, the chief of the U.S. Geological Survey’s Northwest Field Office.

The thefts were discovered over the past week as one gauge after another went offline, starting at about 6:45 p.m. May 18, on the Sauk River near Darrington.

“What they’ve taken so far is all of our deep-cycle sealed batteries,” Miller said.

The 12-volt batteries are used to power the stations out in the wilderness, and are recharged with solar panels.

More outages followed at 9 p.m. May 18 on Mill Creek near Lake Whatcom, 3 a.m. May 19 on the White Chuck River above Crystal Creek, 9:45 a.m. Saturday on the Cascade River near Marblemount, and at 8 p.m. Sunday on the Sauk River about halfway between Darrington and Concrete.

Miller said the gauges, which are used by local governments and utilities as well as anglers, kayakers and other back-country enthusiasts, should all be back online by the end of the day Thursday.

All of the housings had to have new locks installed, he said, and some of the other equipment was damaged.

When the thieves took out the battery at the Marblemount site, they short-circuited the data logger and radio that transmits to the satellite, Miller said.

“It fried out the whole system,” he said.

The Sauk-Suiattle Indian Tribe, which also operates stream gauges, was hit at two locations, said Scott Morris, the tribe’s water quality coordinator.

“The one thing that’s a big loss is we lost a data logger, which is a spendy piece of equipment, and totally useless to whoever took it,” Morris said.

The thieves took solar panels from the site along the White Chuck River, which also is used by the USGS.

The cost to the tribe is more than $10,000, not including labor, Morris said.

Another stream monitoring site operated by the tribe on the Suiattle River was hit back in January, Morris said.

Miller said the USGS received one tip so far from someone who saw a pair of suspicious people near the Darrington site shortly before it went offline. That tip has been passed along to the Snohomish County Sheriff’s Office.

The Skagit County Sheriff’s Office and the Bellingham Police Department are investigating the incidents that occurred in their jurisdictions, Miller said.

Miller said that anyone who sees anything out of the ordinary near one of the USGS stations should call 911 to report it.

Chris Winters: 425-374-4165; cwinters@heraldnet.com. Twitter: @Chris_At_Herald.