Proposed regulations to guide sheep grazing in the Weminuche Wilderness are so weighty that the level of environmental examination of the issues is being ramped up a notch.

The original Environmental Assessment of the plan - for which an unusual second public comment period was opened - has been suspended to allow preparation of a more comprehensive Environmental Impact Statement (EIS).

Kara Chadwick, recently named supervisor of the San Juan National Forest to replace Mark Stiles, broke the news Thursday to Club 20.

Chadwick cited public interest and the complexity of the analysis as the reasons for increasing the intensity of the environmental test.

Public concern about sheep grazing in the Weminuche Wilderness, which has been going on for 100 years, has drawn intense scrutiny since scoping began in February 2012.

Concerns center on the impact of grazing on soil, water and native vegetation, degradation of the recreational experience, the economics of competing interests and, perhaps most importantly, the risk of domestic sheep transmitting diseases to Colorado bighorn sheep arriving in their summer range.

Specifically:

Intertwining sheep trails and ovine grazing, which leave bare soil exposed, encourage the invasion of non-native vegetation and erosion that allows debris to find its way to streams and reservoirs.

Denuded land and sheep droppings with their accompanying flies are the antithesis of what visitors expect to find in wilderness.

Jimbo Buickerood, public lands coordinator at San Juan Citizens Alliance, said he receives complaints about encounters with aggressive guard dogs from hikers and bicyclists.

Grazing fees are low when compared with what hunters pay for a tag and the chance to bag a bighorn.

John Mumma, former head of the Colorado Division of Wildlife (now Colorado Parks and Wildlife), addresses the return on investment for the government in a June 10 comment to the Forest Service.

The $1.35 that sheepmen charge monthly for every five ewes and their offspring is less than the cost of a cup of coffee, Mumma said.

"This year at auction, the Colorado bighorn sheep tag sold for $130,000, and the raffle held in addition to the auction brought $78,200," Mumma wrote.

The risk of bighorns picking up diseases from domestic herds was of concern among commenters.

A grazing-allotment boundary expansion of 3,000 acres proposed in the EA makes contact between domestic sheep and bighorn more likely, said Gary Skiba, a retired Division of Wildlife biologist.

Skiba uses terms such as "questionable data" and "dubious accuracy" in addressing the risk-of-contact ratings used in the EA.

Impacts of grazing management changes on the pika, a rabbit relative that is fleeing from warming temperatures, also should be addressed, Skiba said.

Comments on the EA received by the Forest Service in two 30-day periods totaled 116 from discrete individuals or organizations and 312 form letters from WildEarth Guardian members. The latest comment period ended July 21.

The EA was being conducted under guidelines of the revised San Juan National Forest Land and Resource Management Plan finalized last year.

An EA contains a brief description of a project and the reasons for it, possible alternatives and the environmental impacts of all options. An EIS is a detailed analysis to assure that National Environmental Policy Act goals are met in projects expected to have significant impact.

Under scrutiny in the Weminuche grazing EA were 166,627 acres in La Plata, Hinsdale and San Juan counties. About 162,600 acres of the wilderness are in the national forest.

Grazing would continue to be an appropriate use of public land in a revised plan that meets desired resource conditions or moves them in that direction, the EA says.

There are about 44,500 acres of potential overlap of bighorn and domestic sheep range, with fewer than 1,000 acres in active grazing allotments, the EA says.

The goal is to eliminate overlap and keep domestic sheep away from bighorns. Also, seven vacant allotments would be closed, and five active allotments eventually would be phased out.