Fish enduring man … so far
Conservationists say the value of rivers is incalculable.
Less than one-half of 1 percent of all land in Colorado is riverbed, said Tom Cardamone, director of the Aspen Center for Environmental Studies. Yet 80 percent of all nesting birds nest there and 75 percent of all native wildlife species spend at least part of their life cycle there, he said.
“That one-half of 1 percent is also the most desirable land to build a house and plant bluegrass,” Cardamone observed.
Replacing natural vegetation with bluegrass, boulders and other landscaping elements can destabilize riverbanks, leading to a variety of other problems, including erosion, pollution and floods.
But man usually gets what man wants. The U.S. Environmental Protection Agency estimates that 60,000 acres of wetlands are consumed in the country every year. That rate of loss has slowed since it reached its height in the mid-1950s to mid-1970s, according to the EPA’s Web site.
Colorado is one of 22 states that has lost at least 50 percent of its estimated wetlands since settlement began by white men, according to the EPA.
Delia “Dee” Malone, a biologist and environmental scientist, said rivers and their banks are valuable because they serve as huge filters or sponges that protect water quality in streams. Water rushing down hillsides toward a river settles on the banks and potentially harmful sediments get captured, she said.
In other cases, rising waters from a flooding stream flow onto and over the riverbanks and dump fine sediments there. Willows along rivers even act to slow raging waters and absorb some of the river’s energy, she said.
Leaving a natural barrier between a bluegrass lawn and the river, for example, could also help catch chemical fertilizers, Malone said Cities and towns across the country are establishing ponds or wetlands where storm-water runoff settles before moving on to natural waterways.
Aspen, for instance, uses a pond in two of its local parks to capture street runoff and filter it before it reaches the Roaring Fork. Basalt plans to create a similar pond.
Water quality remains high
It’s easy to get worked up about effluent from worn-out septic systems or golf-course fertilizers, said Alan Czenkusch, an aquatic biologist with the Colorado Division of Wildlife, but fine sediments pose the biggest risk to water quality.
Fine sediments fill the small spaces and tunnels on the stream bottom beneath rocks. Those nooks and crannies are home to stonefly and mayfly larvae – macroinvertebrates that comprise a large part of the diet for trout, Czenkusch said.
Caddis flies, incidentally, tend to live on the tops of rocks.
Left to itself, nature finds a perfect balance – “armoring” the river bottom to hold fast during high runoff, but not filling the nooks and crannies where insect larvae live, Cardamone said. Even during spring runoff, when the rivers resemble chocolate milk, nature won’t line stream bottoms with fine sediments.
But erosion from improperly protected yards and at riverside construction sites can create problems by dumping soil into the stream, said Czenkusch. That’s why the barriers set up at construction sites near waterways are so important. Placed properly, they can prevent loose dirt from spilling into the river.
Czenkusch also said he has seen no evidence that fish populations on the Roaring Fork or Fryingpan rivers are declining, so he’s optimistic that the habitat remains “adequate.” It’s not optimum, however, “because of all of man’s activity,” he said.
“I think from a habitat standpoint, if anything was way out of whack we’d see it,” he said.
The Roaring Fork Conservancy has tested 24 sites along the river for the last five years. It looks for the presence of metals, nitrates and coliform that could pose threats to water quality.
“I think we’ve had good water quality and we continue to have good water quality,” said Rick Lofaro, conservation director and supervisor of the water-quality testing for the Roaring Fork Conservancy.
Malone said the testing she does for the presence of insect larvae in the riverbed also indicates good health.
Czenkusch is somewhat skeptical about the wildlife division’s fish counts because they are just a snapshot in time. He places greater stock in the fact that he hasn’t heard complaints of declining fish populations from the numerous guides that work the rivers.
Tim Heng, general manager of Basalt’s Taylor Creek Fly Shop, said, “We’re catching as many fish today as we were 20 years ago.” He has been a guide since 1981 and has been fishing locally since the early 1970s.
One change, he said, is greater numbers of brown trout and fewer rainbows. Rainbows have a tougher time reproducing because they spawn in the spring, when runoff can scour the river bottom.
The lower section of the Roaring Fork River, from the confluence with the Crystal to the confluence with the Colorado in Glenwood Springs, remains a “Gold Medal” trout fishing stream in the eyes of the division of wildlife. The Fryingpan River below Ruedi Dam also holds that distinction. To earn it, there must be “60 pounds of trout biomass per surface acre” and at least a dozen trout over 14 pounds per surface acre, according to Czenkusch.
“In other words, there have to be a lot of fish and some of them have to be big,” he said.
Cardamone, who is all for letting nature set its own course, doesn’t believe Roaring Fork Valley residents have as much leeway these days if they want to maintain high water quality and premium fish habitat.
“We’ve unsettled things enough,” Cardamone said, “that we have to intervene to stabilize the river system,”