Below the Surface

Overview:

Search and rescue teams face some of the most demanding and dangerous conditions imaginable. Advanced tools like side scan sonar help search and rescue teams work more efficiently while reducing risk.

When tragedy strikes, search and rescue teams face some of the most demanding and dangerous conditions imaginable. Whether responding to water rescue emergencies or recovery operations, these specialized units must often navigate dangerous underwater environments.

Search and recovery operations can happen at any time, in any weather. Teams often work with a sense of urgency. One of the bigger challenges for these teams lies in balancing speed with safety during critical operations. Rigorous training and sophisticated equipment facilitate the process under pressure. In water emergencies, advanced tools like side scan sonar help search and rescue teams work more efficiently while reducing risk.

People gather along a river with heavy foliage and a white sign with black lettering reads "Hazard Ahead." — The ongoing search at Dillon Falls has been dangerous and time-consuming. *Courtesy: Deschutes County Sheriff’s Office*

Why water searches are so complex

Search and rescue operations are far more complex in water than most people realize. Along the Deschutes River, swift currents, underwater rocks, low visibility and tough terrain can make searches difficult. The recent search efforts for three people who went over the rapids at Dillon Falls have been particularly challenging; the search is still ongoing for one of the missing persons.

The incident began on July 19 when a group was floating the river and missed their takeout point. Deschutes County Sheriff’s Office Public Information Officer Jason Carr explained: “The investigation remains ongoing, but the detectives have told me they weren’t able to pinpoint exactly where the group got into the water — only that they had been floating for some time before missing the takeout at Dillon Falls Day Use Area. They were not wearing PFDs [personal flotation devices].”

Lt. Nathan Garibay of DCSO Special Services and Emergency Management explained the factors that make Dillon Falls so dangerous.

“Dillon Falls is considered Class IV whitewater or advanced, but I would characterize it as violent Class IV and is over a quarter-mile long and travels through a gorge with vertical sides composed of lava rock. Many areas are virtually inaccessible, with other areas requiring technical rope access and/or hampered by thick brush.”

These circumstances can be dangerous for search and rescue teams. “In addition to risk of entrapment, there is risk of bodily injury to a responder from being washed into logs and lava rocks,” Garibay said. Due to these hazards, local search and rescue teams have proceeded with extreme caution. When California diver Juan Heredia volunteered to assist in the search, the Sheriff’s Office turned him away because “that stretch of the Deschutes River is closed while they are performing their search.”

Search technologies and operations

There are four main investigative techniques used in a water search, explains Alastair Ruffell, research associate in Geoforensics: location, sonar, radar and dogs. Search technologies, like sonar and radar, are invaluable tools but they also have specific limitations.

At Dillon Falls, much of the actual searching involves people working from boats, along the shore, wading into areas or deploying divers underwater. Swiftwater rescue support with specialized training can also get into the water and search or use underwater cameras. But, adds Garibay, “the moving, turbulent and aerated water can make visibility difficult in some areas and the falls are very hazardous.”

Side scan sonar, which is used to locate missing evidence, drowning victims and submerged vehicles, has been used in the recent Dillon Falls incident. It works by generating detailed images of the underwater environment, regardless of water visibility. The system can scan several hundred feet of underwater terrain from the surface. The sonar’s acoustic beam bounces off objects on the bottom, transmitting data to the surface where detailed images are displayed and analyzed.

Although it is sophisticated enough to create detailed images of riverbeds and objects, side-scan sonar cannot penetrate reed beds or vegetation along riverbanks. “Cameras and other equipment have significant limitations in these conditions due the extremely fast and strong current and poor visibility,” Garibay noted about operations at Dillon Falls.

In water with low visibility or along riverbanks, drones with sonar or radar technology assistance can perform searches far more quickly than just a human. In the Dillon Falls search, crews have used high-definition cameras to look for out-of-place objects. In combination, these technologies can improve recovery success rates and reduce the time needed for focused underwater searches by divers, explained Ruffell.

The scale of search and rescue

The amount of time, money, and effort that goes into search operations can be substantial. Costs include equipment, paid staff time, meals and fuel. Since the Dillon Falls case remains active, officials have not yet calculated the total cost. Garibay has pointed out that the community has stepped up to help by donating finances or meals for the responders.

The search has involved people working from boats, along the shore, wading into areas or looking underwater. “As of today, we have had 18 operational periods and over 2,200 hours of personnel time assigned to the search — with the overwhelming majority professional volunteer time,” Garibay said.