Mountain rivers grapple with the landscape

Scott Condon
This manicured lawn on the Roaring Fork River near Aspen may look more appealing than the shaggy, natural vegetation in the foreground, but biologists say native grasses and willows provide far better erosion control and make for a healthier river. Aspen Times photo/ Nick Saucier.

It doesn’t require a degree in aquatic biology to realize there is something fishy going on at the confluence of Castle Creek and the Roaring Fork River.Walk upstream just a few steps on Castle Creek and you’ll see some of the most clear, clean, inviting waters in the world. It’s so clean, in fact, that you can imagine the pure white snow melting high above timberline and feeding the stream. Just a bit of green algae covers the rocks on the creek bottom.The Roaring Fork River isn’t exactly a roiling cesspool, either. Before warm temperatures melted enough snow to turn the river murky and turbulent, it was also running clear. But the contrast to Castle Creek was easy to detect, even for an untrained observer. The rocks in the Roaring Fork wear a thicker coat of algae and it is much darker than Castle Creek.John Emetic, an aquatic biologist who taught for 23 years at the Colorado School of Mines in Golden, and Delia “Dee” Malone, a biologist and environmental scientist, have no easy explanation for the difference.Emerick suspects the heavier, darker algae on the Roaring Fork indicates heavy loads of nutrients entering the river, perhaps from lawn fertilizers, street runoff and leaky septic systems.”I see it as a warning sign that we’re probably overloading the river with nutrients,” said Emerick, who, along with Malone, is measuring conditions along the river.If nutrients build to levels the river can’t absorb, then bug and fish populations could drop and the river could lose its intrinsic and economic value as wildlife habitat.Big impact from private land The Roaring Fork Conservancy estimates that 75 percent of the Roaring Fork River’s watershed is public land, where land development doesn’t pose much of an environmental threat.

“The pressure on the remaining 25 percent, however, is enormous,” said the conservancy’s latest newsletter.The conservancy and other environmentalists say major issues facing the river include:• An estimated 15 percent of the water in the Roaring Fork basin is sucked through so-called trans-mountain diversions that send water through the Continental Divide to thirsty Front Range cities like Canon City and Pueblo. The watershed also irrigates 280,600 acres of farmland in the Arkansas River Valley. Sending the water east lowers flows in the Roaring Fork and the Fryingpan.• Ruedi Reservoir (on the Fryingpan) and Grizzly Reservoir (on Lincoln Creek, a Roaring Fork tributary) further control flows on the rivers. The dams provide flood control, but conservationists also lament that the rivers’ “signature” – the seasonal fluctuations, flooding in the spring and drying out in the fall – has disappeared.• Housing development, of varying densities, lines the Roaring Fork River almost continuously from Tagert Lakes, four miles east of Aspen, to Glenwood Springs. Other locations are being developed because of their proximity to the river. One new project, ironically called Roaring Fork Preserve, will actually chew up more land adjacent to the river.• Residential development has brought manicured lawns right down to the river’s edge. Kentucky bluegrass has replaced the natural jumble of biologically-rich riparian areas.. These areas can be year-round wetlands or just flood plain, where traditional spring runoff flowed among willows, tall native grasses and other thick vegetation.• Development and urbanization pose threats to water quality. The riparian areas are natural filters that absorb pollutants, like gas and oil residue from Aspen’s streets, fertilizers and herbicides from lawns and golf courses, and waste leaching from aging septic systems.Emerick said he believes there is evidence that the river has so far been able to absorb the effects of mankind. Many measurements indicate that the Roaring Fork’s water quality is still high. But as the Roaring Fork Valley’s population grows – from 8,000 people in 1950 to about 37,000 in the year 2000 – he questions if the river can continue to dilute what is dumped into it, and if it can support the number and diversity of creatures it does now.’Stay out of its way’The first thing many people do when they buy property next to the river, be it in Aspen, Woody Creek or the Aspen Glen golf club down stream, is tear out the clumps of willow trees, mow down the tall native grasses and forge new access to the water.Nothing could be worse, according to Alan Czenkusch, an aquatic biologist with the Colorado Division of Wildlife. Czenkusch gets the call when people want to stabilize a riverbank the proper way. Even the Aspen Center for Environmental Studies enlisted his help.”The best way to manage a river is to stay out of its way and let it do what it wants to do,” Czenkusch said.He said he also believes in leaving the riverbank alone. Most of the Roaring Fork Valley floor is comprised of mixed soils and cobblestones that lack any cohesion. The roots of willows and native vegetation stabilize the bank and help it resist erosion, Czenkusch said.Along the south side of the Roaring Fork River from its confluence with Castle Creek to Slaughterhouse Bridge are several homes at the river’s edge. A handful of homeowners have left the willows and towering blue spruce, the roots of which also cement the soils. But most homeowners have ripped out the vegetation for riverside patios. In many cases they strategically placed large boulders along the bank to stabilize it and prevent the water from eating away at their lawns.The same pattern is followed along the entire course of the river, according to Malone.She and Emerick helped create Big Country Resource Conservation and Development to assess conditions along the Roaring Fork, Fryingpan and Crystal rivers, and several major tributary streams, 240 stream miles in all. When the inventory is finished next year, Big Country hopes to educate governments on issues facing the river and help them find money for solutions. They also hope to educate homeowners on why wiping out natural vegetation harms the river environment. Emerick said the river will gnaw away at the riprap and the soils behind it – attempting, in its own patient way, to restore a natural setting. Eventually it will succeed.”They might lose half their back yard, but it will repair itself,” he said, eying a property where the homeowners tried to conquer nature.Czenkusch agreed boulders placed on the riverbank represent a short-term delay in the erosion process. A 100-year flood will send the boulders tumbling downstream, he said.Meanwhile, the riprap has a detrimental short-term effect. Man-made barriers that prevent the river from spilling over its banks into the flood plain create a stronger flow in the main channel and allow the river to harness more power. When the river is allowed to spill its banks into lowlands, it dissipates its energy, easing the threat of destructive flooding.In Czenkusch’s words, riprap and other barriers just tend to increase the stream’s “irritability.” That ultimately increases the risk of flooding downstream.

It’s not only homeowners whom conservationists are worried about. The Roaring Fork Conservancy is closely monitoring the town of Basalt’s work on a new riverside park. The Conservancy hopes riverside work there is completed in a way that doesn’t exacerbate flooding problems downvalley.==========================================Roaring Fork facts• The Roaring Fork runs 60 miles from the headwaters near Independence Pass to Glenwood Springs, where it joins the Colorado River.• The overall Roaring Fork watershed is 1,451 square miles, roughly equal to the state of Rhode Island. • The river and its tributaries total 1,962 stream miles.• In an average year, the Roaring Fork basin will pump 307 billion gallons of water into the Colorado River.• Anglers and other tourists who visit the lower 13 miles of the Fryingpan River pump $2.6 million into the area’s economy.• Visitors to Ruedi Reservoir added another $147,000 in direct spending.==========================================

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