Environmental Assessment

AFFECTED ENVIRONMENT & ENVIRONMENTAL CONSEQUENCES CHAPTER 3
For comparison purposes, and using the above figures, including the estimated 195 tons per acre of PM10
generated by a wildfire, the 1,644 tons generated under Alternative 2 and the 1,324 tons generated under
Alternative 3 correspond to a wildfire of approximately 8.4 and 6.8 acres respectively. Given that fuel
reduction treatments are proposed on approximately 26,830 acres under Alternative 2 and 23,990 acres
under Alternative 3, a wildfire of comparable acreage would generate an estimated 5,231,850 tons of
PM10 under Alternative 2 and approximately 4,678,050 tons of PM10 under Alternative 3.
In addition to lower production of PM10, both action alternatives would also spread the emission of
PM10 out over a period of years, with only a relatively small portion occurring at any one time or during
any given year. This is in strong contrast to a wildfire which would produce the entire quantity within a
relatively short time period, days or weeks at most.
Prescribe fire activities are also implemented during periods of specified weather conditions which
control the rate and quantity of material consumed, the amount of smoke generated, and the direction in
which the smoke travels. This allows smoke to be directed away from populated areas such as the City of
Bend or away from the Observatory. In the case of the observatory, it also helps to minimize the period
of time that particles are suspended in the atmosphere and potentially impacting astronomic observations.
Under wildfire conditions, managers have no control on any of those or any of the other factors that
determine the quantity or direction of smoke and PM10 and smaller materials.
All burning would be conducted in compliance with the National Ambient Air Quality Standards and
Oregon Department of Forestry Smoke Management regulations and restrictions. Burning would only
occur during favorable existing and forecasted weather conditions to assure smoke dispersion away from
the community of Bend. Burning would also be coordinated with the staff at the Pine Mountain
Observatory to minimize impacts and disruptions to both people and research.
Cumulative Effects - Implementation of Alternative 1 would have no cumulative effect on slash disposal
activities within the air-shed in which the Opine planning area is located. No slash disposal work would
be necessary under this alternative. Alternatives 2 and 3 do have cumulative impacts slash disposal
activities within the air-shed. The amount of particulate matter permitted to be entered into the
atmosphere is determined by the State of Oregon through smoke management regulations administered by
the Oregon Department of Forestry. Slash disposal activities are given permits to burn on a first come,
first served basis. Once the daily limit or quota is reach, subsequent projects are rejected and required to
apply for following days. This has the potential to extend the time necessary to treat all the slash and
hazardous fuel loadings that need to be treated and increasing the risk for those areas which are not or
cannot be treated due to smoke management requirements and limitations.
A concern voiced by the Observatory is the effect dust has on not only the ability to view the night skies,
but also its effect on sensitive equipment. Fire, both prescribe and wildfire, produce particulate that
contribute material to the atmosphere that affect not only clarity of the night sky but also potentially the
sensitive equipment used. Under Alternative 1, the primary local sources of particulate pollution would
remain dust generated by vehicle traffic. Wildfires would become the predominant source if and when
they occur. In contrast to dust from local roads and trails generated by vehicles which tends to be
relatively short in duration and localized in extent, particulate associated with burning tends to be long
lived and more extensive in area. Wildfires, especially uncharacteristic ones, can greatly reduce both the
clarity of the sky and affect the workings and sensitivity of the equipment for extended periods of time by
significantly increasing the volume of material present in the atmosphere.
In contrast, Alternatives 2 and 3, because of the limitations imposed by smoke management rules and
burning prescriptions, produce less particulate matter and result in lower levels of atmospheric
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