For Capt. Ralph Steiger, launching his 21-foot walleye boat out of Chicago harbors last year had become a precarious affair.

 Lake Michigan had receded to an all-time low, and where water had been, exposed rocks, rebar and driftwood remained. By fall, the lake was so low at Burnham Harbor that Steiger's boat could not safely slide off the ramp.

 This year, however, Steiger's launching luck has changed — buoyed by thick winter snowpacks and heavy spring rains that have raised Lake Michigan by about 21/2 feet from its record low in January 2013, at least temporarily alleviating more than a decade of persistently low lake levels.

 The extra water has slid up shores, helping to replenish wetlands and shoreline habitats, blanketing hazards, cushioning boat launches and boosting cargo ships full of coal, iron ore and limestone.

 “It just makes your life a little easier,” Steiger said.

 Although Lakes Michigan and Huron are not projected to hit any record highs in the coming months, scientists predict that they could approach or exceed their historical long-term averages for the first time in more than a decade.

 Formed by retreating glaciers more than 10,000 years ago, the Great Lakes hold an estimated 6 quadrillion gallons of water. Water from Lake Superior — the headwater of the system — runs down to Lakes Michigan and Huron before flowing into Lake Erie, over Niagara Falls into Lake Ontario and eventually the Atlantic Ocean.

 Lakes Michigan and Huron, which are considered one body of water connected by the Straits of Mackinac, are mostly fed by precipitation and runoff and have drifted beneath their long-term average since the late 1990s.

 In January 2013, the average water levels in Lakes Michigan and Huron dipped to 576 feet, the lowest point since modern record-keeping began in 1918.

 The all-time high of 582.3 feet was set in October 1986, representing a sizable range of about 6 feet.

 The lakes tend to follow yearly cycles, swelling in the spring and summer and shrinking in the fall and winter, but they have never in 95 years of recordings remained below average for so long.

 The last two years of relatively heavy winter and spring precipitation, however, have led to this year's stronger-than-usual seasonal rise, according to Keith Kompoltowicz, chief of watershed hydrology for the Army Corps of Engineers Detroit District.

 “We saw a tremendous amount of snow,” Kompoltowicz said of this winter. “We haven't seen snow like that in a long time.”

 In fact, the snowpack around the Michigan basin this year was 30 percent higher than at any time in the past decade. The past two months have also supplied above-average amounts of rain, quenching parched harbors and popular fishing holes like the Lincoln Park Lagoon.

 “There were actually bass that were up in the 1-foot shallows bedding up (this year),” said Capt. Kevin Bachner, owner and operator of Kingfisher Charters. “Last year, there were just rocks there and they would have needed legs to get there.”

 Westrec Marinas, the company that manages Chicago's harbors, has reopened dozens of slips along the lakefront that were unusable last year because of shallow water, according to Executive Vice President Scott Stevenson.

 “The higher lake levels are definitely benefiting boaters,” Stevenson said.

 Especially those carrying weighty cargo.

 Last month, for instance, the higher water levels meant that one laker leaving from Duluth, Minn., was able to take 2,300 more tons of iron ore onboard than at the same time last year, according to Glen Nekvasil, vice president of the Lake Carriers' Association. Nekvasil estimated that the extra cargo, when turned into steel, would be able to make almost 3,000 more cars.

 “Thank goodness we have more water here, because we really need to make up the cargo we lost,” said Nekvasil, pointing out that record-breaking ice cover this winter also slowed Great Lakes shipping down considerably.

 “We're not home free,” he said.

 Indeed, some scientists have said this year's rise is simply a blip in the context of long-term lake levels that many expect to continue to drop because of climate change. They also point out that given the lakes' tendency to fluctuate, the trend could quickly reverse.

 In 2008 and 2009, for example, Lakes Michigan and Huron also were closing in on average levels, but subsequent dry conditions pushed them back down.

 Given that, Steiger and other users of the Great Lakes said they are appreciating the relatively higher water levels while they last.

 “It can change back to what it was pretty quickly here,” Steiger said. “We'll see what the next couple of years do.”

 cdizikes@tribune.com