Lake Union is a brilliant dimple in the heart of Seattle. A leftover from a distant glacial age, it’s now surrounded by a bustling metropolitan area.

People live in homes floating against its shore and in condos and apartments on dry land. Commercial vessels moor there. Crowds come to its parks. Yacht harbors abound. You’ll find a delightful Museum of History and Industry on its south shore and a Center for Wooden Boats on another. Dot Com businesses fill a crowd of new buildings above its southern shore.

Because it is linked to Puget Sound via the Lake Washington Ship Canal and the Ballard Locks, this small lake (580 acres) is busy all the time with marine traffic, particularly on sunny weekends. Sailors race on Tuesday evening and all boaters love to putt-putt along the shoreline to admire the sights or stop at a restaurant.

The lake also boasts an international airport – one served by Beaver and Otter float planes flown by pilots for Kenmore Air, as well as by private planes, all of which land on the water and taxi to terminals on the shore. The problem is obvious: how to keep everyone using the lake safe as the lake becomes more congested.

Now, there’s a move on to create a marked lane on the lake to improve safety by separating air traffic from boats during peak periods. Although there are no recorded accidents involving aircraft and boats, Kenmore Air and the city of Seattle sought and won a state construction grant of $67,000 and are planning to install six buoys marking an aircraft lane 300 feet wide and 3,500 feet long. Installation will begin in October.

If approaching pilots judge the lake too crowded for safety they will use a radio signal to activate flashing lights on the buoys. Boaters, seeing the warning lights, will be required to steer away from the landing lane until the lights switch off. (Similar systems are used by land-based aircraft to switch on landing lights at unattended airports.)

The lake has been important for aircraft since 1916, when the Boeing Co. built its first airplane (a float plane) and launched it from the foot of Roanoke Street on the lake shore.

I lived in a floating home on the east shore of the lake for a decade, a half block from that Boeing launch ramp. On summer days I’d sit on my roof and watch as yellow Kenmore planes appeared in the north and then marvel as the pilots managed to find a clean landing path among scores of boats sailing and motoring on the lake. Sometimes I was out there in my boat and would duck a little as a venerable Beaver soared by overhead.

The city will manage installation of the buoys and Kenmore Air will install cockpit control gear in its aircraft and deal with a related challenge – informing boaters about the boating safety lane and how it will work.

Chuck Perry, Kenmore Air’s senior pilot, recently briefed the board of the Recreational Boaters Association of Washington as part of its educational campaign. The board voted to endorse the vessel safety lane project.

“We think it’s something that’s needed,” Perry told me in an interview. “We will only need it a few times a day . . . for about 10 minutes each.” He said the worst congestion occurs on warm weekend evenings. “Everyone is down there then.”

Perry said Kenmore schedules five flights in and out of its Lake Union terminal daily during the busy summer months. Traffic is lighter the rest of the year.

One of the wildest and most popular boating activities on the lake is the Tuesday night Duck Dodge. In an event that’s been ongoing for decades, hundreds of sailboats race around buoys while crews consume significant quantities of brew. Kenmore Air planes stay away from the lake those evenings, depositing passengers instead at a terminal at the north end of Lake Washington in the community of Kenmore, a Seattle suburb.

Many cruising boaters know Kenmore Air operations well because its float planes fly to the San Juan Islands and to major ports and popular harbors in British Columbia. Traditionally, skippers will greet guests or new crew in places like Friday Harbor, Nanaimo, Port McNeill or Sullivan Bay – and then later put them on a plane to fly home.