Project spotlight
An aerial drone and an underwater drone for MIPD’s Marine Patrol. Both would help officers find people faster on Lake Washington, on the surface and in the deep water below it. This goal would give the Marine Patrol its first drones, for work its officers already do.
What it is
MIPD’s Marine Patrol covers the waters of Mercer Island, Bellevue, Renton, Medina, Hunts Point, and Yarrow Point. Its officers answer boating accidents, swimmers in trouble, and people missing on the water. When someone goes under, the first minutes matter most, and the lake is deep and dark below the surface. These two drones give the patrol eyes in both places.
Above the water
Launched from the patrol boat or the shore, it searches a wide area in minutes and sees body heat in the dark, in rain, and in glare off the water. It can drop a flotation device that inflates on contact, so a person in trouble has something to hold while the boat closes the distance. It also helps officers check shorelines and docks when a child or an older adult is reported missing near the water.
Below the water
A remotely operated vehicle, or ROV, goes down on a cable while the officer stays safely in the boat. Its camera and lights show the bottom at depths where divers face serious risk, and its grabber arm can secure a person so they can be brought to the surface.
The challenge
The lake averages about 108 feet deep and reaches 214 feet at its deepest point. Under the I-90 floating bridges, the water runs about 150 to 200 feet deep.
Recreational diving usually stops at about 130 feet. Deeper than that, divers need technical training, special gas mixtures, and long decompression stops on the way up. At the bottom of Lake Washington, the water is cold, visibility is close to zero, and the bridge’s anchor cables add another hazard.
In a recent search near the I-90 bridge, partner agencies flew thermal drones over the water, and the deep-water work relied on side-scan sonar and an underwater drone brought in from outside the department. With its own equipment, the Marine Patrol could begin that work on the first day.
The map shows the middle of the lake. The deepest channel runs west of Mercer Island, under and just north of the I-90 floating bridges, where the bottom drops past 200 feet. The East Channel, between Mercer Island and Bellevue, is far shallower, mostly under 70 feet. Marine Patrol officers say many of their boating calls come from the west side of the lake, near the bridges.
An underwater drone rated past 214 feet can reach every part of this map. In the deep water west of the Island, it works where a recreational diver cannot. In the East Channel and along the shore, it still matters: it can search at night, stay down longer than a diver, and run a search pattern the Marine Patrol can review later.
The aerial drone helps anywhere on the surface, deep or shallow. It can find a person quickly, drop a flotation device while the boat is still closing in, and guide the Marine Patrol boat straight to them.
On the water
Each of these is work the Marine Patrol already does. The drones help officers do it faster and with less risk.
A person who falls from a boat or tires while swimming may have only minutes. An aerial drone can be over the scene before the boat arrives, find the person by body heat, and drop a flotation device that holds them up until officers reach them.
When a search moves to the bottom, the underwater drone goes first. It can work at any depth in the lake, for as long as its battery lasts, without putting a diver at risk. Divers still go in when it is safe, with the drone showing them exactly where to go.
Sometimes the work ends in a recovery. For a family, every day of waiting is hard. Having the equipment on the boat, instead of waiting for outside help, can shorten a search from weeks to days or hours.
Photographs show the MIPD Marine Patrol at work.
Limits
These drones are for search, rescue, recovery, and water safety. The chapter is not funding drones for routine patrol or for watching residents, and neither drone will carry anything other than cameras, lights, a grabber arm, and a flotation device. MIPD sets the rules for when and how the drones are used, and the chapter will ask that those rules be shared with the public. Every flight and dive follows MIPD policy and FAA rules. Chapter gifts buy equipment and training. They do not pay for positions, overtime, or upkeep beyond the first kit, and the chapter will report back on what was bought. A drone does not replace an officer or a diver. It helps them get to the right place sooner and more safely.
Already working nearby
The Pierce County Sheriff’s Office uses an underwater drone with video, sonar, and a robotic arm to find people in water deeper than 100 feet, and it can be in the water in about five minutes. In 2023, its Metro Dive Team, which serves Pierce County, Tacoma, and Lakewood, received federal funding to replace a 20-year-old ROV with a new one that has a grabber and sonar.
Bellevue runs a Drone as First Responder program for police and fire calls and lists search and rescue among its drone uses. During a recent search near the I-90 bridge, the Clyde Hill Police drone unit helped MIPD search the water.
At Lake Tahoe, a local resident donated an underwater drone to the Douglas County Sheriff’s Office, and marine deputies used it to help recover a drowning victim. In Wisconsin, La Crosse Police drones now drop flotation devices to people in trouble on the river.
Making gifts go further
A full search and recovery setup, with an underwater drone, sonar, and a thermal aerial drone, can cost $100,000 or more. Many public-safety grants require the department to put up part of the cost, often about 25 percent, before the grant pays the rest. If MIPD pursues one of these grants, chapter gifts can serve as that local share.
Washington State Parks passes federal boating safety money to police and sheriff’s marine units with approved programs. Agencies that receive it typically pay a 25 percent match.
Federal programs such as the Byrne Justice Assistance Grant help local departments buy equipment. Pierce County’s new underwater drone, described above, was paid for with federal funding secured for the Metro Dive Team.
Some foundations fund water rescue directly. In Nevada, a private foundation paid for the Washoe County Sheriff’s Office’s side-scan sonar and its first underwater drone.
Grants are competitive. MIPD would decide which grants to pursue and would apply for them. The chapter’s role is to have the local share ready, so the department can move when an opportunity opens.
Cost
The first priority is a compact underwater drone rated past the lake’s deepest point, with a camera, lights, and a grabber arm, along with flotation devices and operator training. If funds allow, the goal is to also purchase a thermal aerial drone that can drop a flotation device. Public-safety thermal drones from U.S. makers run about $7,000 to $21,000 before batteries, cases, and a drop kit.
Sonar is not part of this goal. A larger underwater package with built-in sonar costs more; Placer County, California, paid about $73,000 for one in 2025. MIPD will choose the models, and the Foundation’s Board of Directors approves the expense. The operators remain MIPD employees, and the chapter does not fund positions.
Facts from the City of Mercer Island, the Washington Department of Ecology, the University of Washington, the Pierce County Sheriff’s Office, the City of Bellevue, Placer County, and news reports.
