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Daddy, What’s a Deciview?

Now comes yet another ginormous regulatory proposal

By Dave Skinner

On April 25, the Environmental Protection Agency issued, yep, another proposed regulation, 93 pages concerning “protection of visibility in mandatory Class I federal areas.”

What the heck is that? Well, be glad you asked.

First, a little background: This all got underway with the Clean Air Act Amendments of 1977, led through the post-Nixon Congress by Democrats Edmund Muskie of Maine and Paul Rogers of Florida, signed into law by President Jimmy Carter.

The larger bill established three basic classes of air quality: Class I (near pristine), Class II (normal) and Class III (safe, but could be better).

A “mandatory” class I area includes national parks, wildlife refuges, wilderness areas, and all international parks in existence as of August 7, 1977. There are 156 of these nationwide. Of course, most are in the West.

Class I areas were allowed almost no increase in particulate matter from “baseline” – the three-hour maximum for sulfur dioxide was allowed to increase 25 micrograms per cubic meter in class I areas, versus 512 mcgcm in Class II and 700 in class III – pretty stringent.

Next was Section 128, second from the bottom, concerning “Visability [sic] Protection.” This original language was two and a half pages, including “prevention of any future, and the remedying of any existing, impairment of visibility” – 13 words that have since spawned countless volumes of new regulations, with entire forests felled for the paper to print them all. EPA was tasked with finding a way to measure visibility, eventually settling on something called a “deciview” – akin to decibels for sound measurement, a linear scale representing a logarithmic function, “the minimal perceptible change in visibility to the human eye.”

Zero deciviews is basically perfect air, visibility of nearly 400 miles. “Normal” air in the high-desert West is 12 deciviews of extinction, about 130 miles, with Montana falling inside the 17 deciview curve, about 65 miles on a normal day. East of the Mississippi, or in the Los Angeles Basin, normal air rates 32 deciviews, about 13 miles.

In a nutshell, Montanans can see four times as far through air with about one-eighth of the guck as back East. No problem, right? Well, EPA’s map linked above makes it clear why Colstrip units 3 and 4, which send much of their power to Puget Sound cities, were built downwind of the seven “mandatory Class I” areas all along the Cascade Mountains crest. That was not a coincidence.

Under EPA’s original 1980 regulations, states were supposed to submit improvement plans by 1987, which mostly didn’t happen. EPA instead began imposing federal plans upon the states. By 1999, at the end of the Clinton Administration, EPA promulgated “regional haze” regulations (61 glorious Federal Register pages) which eventually spawned Montana’s regional haze plan – 57 pages of Acronymese that will either stun you comatose within seconds, or teach you exactly how EPA is using visibility, not public health, to threaten the viability of Colstrip.

Now comes yet another ginormous regulatory proposal that EPA declares will mainly affect “owners and operators of sources that emit particulate matter” less than 10 microns in diameter (PM10) – power plants, mostly.

There is one “positive” item in the proposal: “[C]hange the way in which some days are selected for tracking progress towards natural visibility conditions to account for events such as wildfires;” with the intent of “greatly reducing the trend-distorting effect of wildfires and natural dust storms.” This change is to allow more prescription burning without messing up the progress targets, while ignoring wildfire as “natural.”

But there’s also some major turf-building, to “expand the applicability for reasonably attributable visibility impairment from only states with Class I areas to all states.” Basically, EPA wants to chase “smoke” in the 11 states lacking (and not wanting) mandatory Class I areas, using the relative handful of Eastern “mandatories” as a leverage point.

So, there’s going to be one public hearing, at EPA headquarters in Washington, D.C., where “oral testimony will be limited to 5 minutes.” Nobody, of course, will be testifying about how 13 words written almost 40 years ago brought them there …