A stream runs through it
October 2, 2012
The U.S. Forest Service started construction on Monday, Oct. 1, to replace a culvert located on Little Gravel Mountain Road (FSR 190.1) that will allow Trail Creek to pass under the road with an “open bottom arch” culvert.
The existing culvert, located just past the junction of FSR 190.1 and Stillwater Pass (FSR 123), is referred to as a Perpetual Problem Culvert or PPC.
The culvert will be replaced with an “open bottom arch” culvert that is only the top half of a circular culvert. The shape of the new culverts allows for the creation of a simulated streambed that eliminates all of the problems associated with PPCs.
Trail Creek is the fourth such project undertaken in local forests. Eventually, the Forest Service would like to replace up to 15 culverts in the Sulphur District.
Construction of a bypass for the stream is the first phase of the project, according to Dick Stowers, an engineer for the Sulphur Ranger District.
Concrete footers for the new culvert will sit on top of will be installed after the old culvert has been removed.
Most culverts now are are circular in shape. This circular shape can cause problems not only for the stream and its inhabitants but also for the roads and trails they travel under as the culverts are often not large enough to support the flow of the stream, officials say.
In addition, the bottoms of many circular culverts sit above the streambed, causing a host of problems for the stream ecology: Velocity barriers, meaning the stream travels too fast to allow aquatic organisms to travel through it; jump barriers, where the stream sits too far bellow the bottom of the culvert to allow fish to jump into the culvert; and sediment barriers, where the culvert blocks the passage of sediments downstream.
The main goal behind the open bottom culverts is to make the streambed continuous.
The connectivity of the stream bed is important to allow aquatic organisms passage upstream in order to spawn or to rear their young, said Kelly Larkin-Mckim, a fisheries biologist for the Sulphur Ranger District.
These aquatic organism passage projects are a new and evolving concept that began in Western states to allow salmon populations to move upstream to spawn.
Salmon are not the only species of fish that travel upstream to spawn and to rear their young. Cutthroat trout also travel upstream as do most other species of fish found in the area, Larkin-Mckim said.
Trail creek happens to be the only stream in the Willow Creek Drainage that supports a population of native cutthroat trout, according to Larkin-Mckim.
Other animals will be able to utilize the open bottom culvert as well such as amphibians, insects, and aquatic mammals.
The culvert is designed with extra width to allow creatures to move along its banks without having to cross the road. The extra width also allows the stream to take its own course instead of being forced through a circular culvert.
It has become a region-wide direction that when culverts are replaced they should be replaced with bottomless culverts such as the open bottom arch culvert that is being constructed on Trail Creek.
No travel will be allowed through the closure area during the construction, which is expected to last approximately two weeks. However, ATVs and motorcycles will be able to cross Trail Creek at a ford approximately one-quarter mile downstream.
Another project that recently took place in the area was the “hardening” of a stream bed on North Supply Road.
“Hardening” is improving a stream bed where motor vehicles cross to slow or eliminate the vehicles from kicking up sediment.
This project benefited the clarity of Grand Lake, a hot topic for both the Forest Service and Grand County, as the sediment that was being sent downstream at the crossing eventually flows into Grand Lake.
The county provided equipment, operators, and materials to complete the project at no cost to the Forest Service.