MINNEAPOLIS — Minnesota closed out 2015 with its highest level of boating fatalities in a decade.

Minnesota had 18 boating-related deaths last year, preliminary figures from the Department of Natural Resources show. That’s the most since 23 people died in 2005 and up from the 14 deaths recorded in 2014.

Officials said it’s an unhappy by-product of beautiful spring, summer and fall weather that drew boaters out in droves.

“We had pretty much the ideal season, weather-wise,” said Stan Linnell, DNR boating and water safety manager. “More people were out boating than some other years.”

Minnesota’s boating fatalities fluctuated in the range of 12-16 from 2006-2014. Most of the deaths in 2015 were the result of drownings. Of the 18 fatalities, 10 were men ages 20 to 60 years old who weren’t wearing life jackets. The primary factor was victims falling overboard or boats capsizing.

October was the deadliest month, with five people killed while boating on Minnesota lakes.

The number of nonfatal boating accidents also went up in 2015, at 76 compared with 36 in 2014 and 65 in 2013. Citations for boating while intoxicated stayed relatively flat at 80, compared to 76 in 2014 and 89 in 2013, the DNR said.

Lt. Jackie Glaser, who supervises conservation officers who patrol west metro area lakes and the Mississippi River, said the numbers indicate that people are more prepared to designate a sober boat driver, but they also indicate that boaters need to wear life jackets.

“We never see enough people wearing life jackets,” said Lt. Adam Block, who supervises conservation officers who patrol the east metro including the St. Croix River. “It’s going to save a life.”

While fatalities reached a 10-year high in 2015, the DNR said the long-term trend is still downward. In the 1960s and 1970s, when the DNR first started keeping count, boating deaths neared 60 in some years, but fell steadily over the next few decades as education and enforcement ramped up.