State of the Rivers – the Gallatin, Madison and Upper Yellowstone

By Taylor Anderson 

This year’s heavy winter snowfall and wet spring coated the high peaks with lavish snow. Chilly, early spring weather may indicate a long runoff until the higher temperatures of summer hit. This will give Montana’s rivers with nice spring flush—benefitting these ecosystems with the cleaner river bottoms and new habitat that come with higher flows.

GALLATIN RIVER

Locals sometimes take the drive along Highway 191 from Bozeman to Big Sky through the Gallatin River Canyon for granted. For miles, high peaks hover over its narrow valley, clear to Wyoming, paralleled by the path of the winding Gallatin River.

The area saw an abundance of snowfall last winter, and the Gallatin River Basin gathered 26 percent more precipitation than the 30-year average, 43 percent higher than the same time in 2010. In mid-April the Gallatin was discharging at 309 cubic feet per second, down from its 368 cfs average, and received a late two feet of snow.

According to Mike Vaughn, a Madison and Gallatin area fisheries biologist with Montana Fish, Wildlife and Parks, trout flourish at the higher stretches of the Gallatin, but numbers are biggest in the Canyon.

The higher stretches of the Gallatin has, “something on the order of 2,000 fish per mile that are greater than six inches,” Vaughn said. “Down in the Canyon it’s even higher, we run about 5,000 fish per mile. Mostly rainbows.”

They’re not hogs, averaging about eight to 14”. The cold water isn’t ideal for trout movement or growth. Warmer temperatures bring more bugs, and the Gallatin streams generally have lots of bugs during the late spring, Vaughn said.

The fourth-highest Gallatin river crest in history occurred in February 1996, when 10.18’ of water in the river overwhelmed banks, fit for around six or seven feet before flooding. The Gallatin can get very low at stretches during the late, dry summer months, and prolonged runoff is preferred.

Higher waters recycle riverbed sediments. Although toxic sediments don’t plague these rivers like they do water near mines and dams like the Clark Fork, (the Milltown Dam Reservoir contained 6.6 million cubic yards of sediment before being declared a Superfund Site), the Gallatin benefits when water washes silt and other fine sediments downstream.

When peak spring runoff will hit is anyone’s guess. The average date for the Gallatin before runoff tapers is June 6, at 5,193 cubic feet per second, but the earliest peak spring runoff date was in May of 1934. Peak runoff has come as late as the fourth of July, in 1975, so pinpointing this year’s date is nearly impossible.

UPPER YELLOWSTONE RIVER

From Gardiner, this river’s enormous power winds north through treacherous mountain terrain until it reaches Livingston, where it turns and heads eastward.

The Upper Yellowstone River Basin received 123 percent of the 30-year average precipitation through April, and the river flowed at 1,910 cfs, well above a 1,429 cfs average for April, but hardly comparing to the 30,000 cfs flows that pounded the region east of Livingston in 1996 and 1997.

Water will wash from icy peaks when temperatures warm in Southwest Montana, and river channels that have been parched for years may be quenched. Channels fill and create new places for younger fish to live and grow, away from bigger predators in the main channel.

The Upper Yellowstone’s relatively enormous size means the riverbed isn’t made of the fine sediment seen in the Gallatin. The limestone rocks and gravel bars are shuffled around and dispersed downstream, and pieces of driftwood and petrified wood scatter its rocky banks.

Trout numbers on the river are steady, and the population last year from Yellowstone Park to Livingston was an estimated 218 brown trout per mile, 525 rainbow trout and 296 Yellowstone cutthroat trout, according to Scott Opitz, the Upper Yellowstone Fisheries Biologist with Fish, Wildlife and Parks.

Opitz said his stretch of water stays fairly cool because of the Park’s high elevations. The river has been closed to anglers only once in his seven years with the service—in 2007, due to warm water.

Trout are temperamental about temperature change. If the river is too cold, they don’t eat. When the rivers are big, the fish tend to hunker down at the bottom of the cool streams and rest. Most fish are caught when it’s warmer, but this can be dangerous for fish health, and guides shy away from fishing warmer streams.

Big water also causes erosion that benefits fish. It digs deep holes that provide some cooler water during late summer months when rivers slow down and have lost spring water. The Yellowstone’s gravel limestone rocks are oxygenated and sent downstream, where they land at shallower stretches to create habitat in fast-moving waters.

The lifelike interplay between the flowing river and its inhabitants is always changing. “The system is made to move around a bit,” Vaughn said.

MADISON RIVER

The Upper Madison meanders a shallow 60 miles of riffled river from the western boundaries of Yellowstone National Park through Hebgen and Quake lakes, then heads north through a beautiful agricultural stretch near Ennis. Its Lower Madison counterpart starts in Ennis Lake and quickly makes its way through narrow canyons toward its final destination in Three Forks, where it meets the mighty Missouri.

Differing from the Gallatin and Upper Yellowstone, man-made dams monitor and control the Madison. There are good and bad aspects to having a controlled flow, Vaughn said. The Hebgen Lake dam assures high flows year round, but the river doesn’t benefit from the high flowing runoffs that clean rivers in early summer.

In mid-April, the upper reaches of the Madison were running at 1,000 cfs, and had 12 percent more than average total precipitation. The Madison below Ennis Lake was right around the average of 1,560 cfs.

Both stretches of the Madison have held steady numbers of fish since recovering from a whirling disease breakout that devastated trout populations for much of the 1990s. Upper Madison fish numbers are around 2,500 rainbows per mile and 2,000 brown trout per mile. Lower Madison levels are about 1,500 rainbows and 1,000 brown.

“We may not have the numbers we had before whirling disease,” Vaughn said, “but the numbers are now fairly strong.”

Bob Merryman is in his 21st year of guiding with the Gallatin River Guides in Big Sky. He said a high quantity of water doesn’t always indicate a healthy stream, and that the right water and air temperature make happy fish.

Merryman said anglers should be careful to know their impact on fish populations during late summer, during high temperature days. The warmer waters of the Lower Madison can be stressful habitat for trout, and catching them during warm water situations often times means hurting the fish.

“If they’re doing catch and release (on warmer days), they should probably just keep them because they’ll probably kill them anyways,” he said.

Explore this three weeks from now on Big Sky, Montana\’s weekly news outlet, the Big Sky Weekly.

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