Summer is right around the corner, and if you're a recreational boater you know what that means: Navigating the Delta is about to make the morning commute on Interstate 680 look easy.

This is the time of year when the greatest number of watercraft, often helmed by inexperienced operators and/or traveling at unsafe speeds, turn Contra Costa County's major waterway into a wet-and-wild beehive of activity.

The county's boating accident total for the last five years is 105, according to the state Department of Boating and Waterways, resulting in 63 injuries and nine fatalities. The pursuit of fun and recreation has too often ended in tragedy.

In this photo taken Monday, Sept. 23, 2013, a boat cruises down the Delta Cross Channel between the Sacramento River and Snodgrass Slough near Walnut
In this photo taken Monday, Sept. 23, 2013, a boat cruises down the Delta Cross Channel between the Sacramento River and Snodgrass Slough near Walnut Grove, Calif. In an effort to stabilize the Sacramento-Sacramento River Delta's fisheries and water supply, The Bay Delta Conservation plan proposes building a tunnel to transfer water from the Sacramento River near Clarksburg to the Clifton Court Forebay near Tracy. (AP Photo/Rich Pedroncelli) (Rich Pedroncelli)

"The No. 1 cause of accidents is operator inattention or excessive speed," said Capt. William Duke of the Contra Costa Sheriff's Office. "Right after that is alcohol impairment and the bad decision-making that goes along with it."

Duke, special operations division commander of the sheriff's Marine Services unit, said lack of boating education also factors into those bad decisions.

"We're one of the few states in the nation that does not have a requirement to pass some kind of test or be licensed before you can operate a boat," he said. "Anybody can get a boat and go out on the water without even knowing the rules."

Right-of-way procedures, equipment needs and safety precautions are only a mouse click away, at the Department of Boating and Waterways website (www.dbw.ca.gov/pubs/ABC/). So is information about boating safety classes.

But Duke says too few people take the time to prepare for the water.

"It comes down to making good decisions," he said. "It could be a crossing situation where two boats are coming together and just knowing how to clear a turn. One of the reasons you see more accidents in the Delta than other waterways is the narrowness of the channels -- sometimes only 100 yards wide.

"And there are stresses that make things worse. You're out on the water all day, it's hot and you're fatigued from the pounding your body takes. The glare of the sun takes it out of you. It all contributes to bad decisions."

The Delta also is a challenge because of the dangers lurking just below the surface. That makes caution the best choice in unfamiliar waters, where one mistake can be your last. The latest fatality Duke worked, only a month ago, came when a power boat operated by two fishermen was ripped apart after hitting a submerged piling near the Old River Bridge, about two miles from Discovery Bay.

Add to all of those concerns another peculiar aspect of California boating: Open containers are permissible on recreational boats -- and their operators are allowed to drink. Only if an operator's blood-alcohol level measures .08 percent or higher can an arrest be made. (Yes, the sheriff's deputies administer sobriety tests.)

Finally, as if one further worry is needed, there are virtually no speed limits on the Delta. The rare exceptions are near docks and in harbors. Otherwise, Duke said, it's "as fast as you can go safely," which means vastly different things to different boaters.

"The big thing to remember," he said, "is when you're driving a vehicle on the streets, all the other drivers have to study up, learn the rules of the road and pass a test before they get a license. There's no such requirement for boaters."

If you're going out on the Delta, be smart. The next three months are not only the busiest of the year but the most dangerous.

Contact Tom Barnidge at tbarnidge@bayareanewsgroup.com