The devices used by the Montana Department of Transportation to prevent sediment erosion from the Beaver Creek Highway construction project are effective and environmentally friendly, MDT officials say. They're also tasty to cattle.
Called wattles, the biodegradable net-like tubes are packed with straw rice and used during construction and other projects to contain silt and sediment. They are being used on the Beaver Creek reconstruction project to prevent runoff until the ground has a chance to revegetate.
"They're really easy to install, and they do a great job of holding in that silt. They're perfect for us," said MDT district administrator Mick Johnson.
"We were told that they were not attractive to cattle, but we have found that to be untrue in Beaver Creek Park," Johnson said. "They love them. We have even used cayenne pepper to try to stop them from eating it."
Construction crews have been able to repair or refill most of the wattles that have been damaged by hungry cattle. The problem is mostly an inconvenience, Johnson said, but cost is also a factor.
"It's a costly solution if you have to replace it. It is not costly if you don't have to replace it," he said. "Straw wattle is about $7 a linear foot installed. Beaver Creek is a 10- mile job, on both sides of the road. It's a lot of money, and then if you have to replace them a couple times, the cost really goes up."
Wattle has not been placed along the entire highway, said Gary Berg, project manager for the Havre office of MDT. Sections of wattle - which come in 25-foot increments - are installed in places of high runoff, he said.
"It's not continuous. We used them where the main points of drainage are near ditches and culverts," he said.
MDT is required by law to limit environmental impact, a responsibility it takes seriously, Johnson said.
"It's our goal to protect that environment out there. The cost is secondary," he said.
Wattle has been used successfully in many construction projects throughout the state, he said, adding that having them eaten is not an issue that often arises.
"It's a problem unique to Beaver Creek because we do have roaming cattle. On other projects, the cattle are fenced off the roadway, so they're not walking all over them, or even eating them," Johnson said.
"This isn't normally a problem we run into because we don't normally have cattle on our roads," said Berg.
Most state highways are fenced on both sides, but state Highway 234 - also called Beaver Creek Highway - was given a special exemption by the 2001 Legislature. Hill County allows ranchers to graze cattle in the park during certain times of year, when as many as 2,500 animals may use the park at one time.
Despite its attractiveness to the cattle, both Berg and Johnson maintain that straw wattle is the best option. Other erosion-control devices include silt fence - made from black fabric or plastic - and straw blankets.
Silt fences are an eyesore and have to be removed once the ground has revegetated because they are not biodegradable, Johnson said. They are also difficult to maintain, he said.
"With plastic, anytime there's a snowstorm or wind, it tears and falls down," he said.
Berg said the straw blankets are easily trampled by cattle.