Releases into the Bighorn River from Yellowtail Dam haven't been this high since 1995.

Water is pouring out of Bighorn Lake behind the dam at nearly 13,000 cubic feet per second, inundating one fishing access and swamping some low-lying areas along the banks of the internationally famous trout stream.

Fourteen years ago, outflows into the river reached 14,000 cfs before falling back.

Water levels in the river and in Bighorn Lake behind the dam have been on a steep upward trajectory since early June, when the pace of snowmelt in Wyoming mountains picked up.

"We had a cool spring that kept everything up in the mountains late into the season," said Tim Felchle, Montana reservoir operations chief for the Bureau of Reclamation. "Near the first part of July things are usually over. That leaves us with a narrow window to manage water."

The 70-mile-long lake that straddles the Montana-Wyoming line was slow to fill, but as of Thursday, water levels were 5.6 feet into the lake's 17-foot flood pool. Felchle expects it to rise another foot or foot and a half. The flood pool refers to storage above the full level of a reservoir's conservation pool to hold the excess in high-water years.

Inflows into the lake had fallen back to 16,068 cfs Thursday, down about 500 cfs from earlier in the week. Felchle said river flows are likely to remain high at least until inflows decline to the level of outflows. He said the balance could be achieved sometime late this week or next week.

The Bighorn River system includes Bighorn Lake as well as Boysen and Buffalo Bill reservoirs in Wyoming. "I think we're starting to see a reduction into the upstream reservoirs," Felchle said. "It seems like most of the high-elevation snow is gone. There is still a little above Buffalo Bill."

Inflows at Boysen are still about 3,000 cfs above outflows. The reservoir is 99.4 percent full. Buffalo Bill is about 91 percent full and inflows are about 300 cfs above outflows.

Felchle said that Reclamation has been carefully monitoring the river for signs of trouble. The only problem he has heard about is flooding at the Grant Marsh Fishing Access seven miles north of Hardin.

Montana Fish, Wildlife and Parks closed the access Wednesday after high water washed out part of the entrance road and inundated the interior road, parking lot, latrine and boat launch. It will remain closed until water recedes.