Water levels in Lake Ontario are about a foot below normal, and 1½ feet lower than they were a year ago, portending a potentially troublesome summer for boaters.

Some problems already are cropping up, but the concern is more for what lies ahead.

Lake levels typically decline a foot between June and September, due to normal seasonal fluctuations, and could be even lower if the summer is a dry one.

“It’s looking like fall water now. So what’s the water going to be like in the fall?” said Bruce Butcher, manager of Sandy Creek Marina in Hamlin.

Very low levels in the late summer or fall could make it difficult for boat owners to pass through channels linking marinas and the lake, or force them to remove their craft from the water earlier than normal.

At present, local marina operators and others are reporting that channels are open to traffic. “We can get boats in and out, but there’s not a lot to spare,” said Frank Ardino, manager of Braddock Bay Marina, which has a notoriously shallow channel linking the bay to Lake Ontario.

Butcher offered a similar report from Sandy Creek, and Al Jaehn, dockmaster at Mayer’s Marina on Irondequoit Bay, said “I’ve seen shallower water. The channel works.”

Butcher noted some problems launching boats, and he and others noted the sizable gap between docks and boats floating next to them, making it harder to get in and out of vessels.

“Some of our older boaters have moved out and come down to the (Genesee) river because they and their spouses find it difficult to navigate from the boats to the dock,” said Ardino, who also manages two facilities on the Genesee. One of them has floating docks, which make for easier boat access.

Dan Barletta, a Greece shoreline resident who served on an international panel that studied lake-level regulation, said residents who hoist boats down to the water from shore may be having trouble, too.

But he also noted the upside — shallower water means wider beaches and makes it easier for shoreline residents to do maintenance work on their breakwaters.

Barletta said the reason for the low water is clear — “We had (comparatively) no snow and no rain. And the upper lakes are down, too.”

Indeed, snow cover in the Lake Ontario basin was relatively light last winter, and it melted early. Rainfall this spring has been below average; Rochester, for instance, measured almost 25 percent less rain than normal in March, April and May.

About 85 percent of Lake Ontario’s water, though, comes not from local rain or snow but from the other Great Lakes. And all four of them are suffering with below-average water levels themselves.

The International St. Lawrence River Board of Control, which oversees lake-level regulation, can sometimes hold back on water released to the St. Lawrence in order to prop up levels in Lake Ontario. That doesn’t seem likely now, as the river at Montreal is 6 feet below average already.