|Sacramento Valley Fall
Project Leader Don Schrukraft, Weathernews, Inc., Chico
|The 2001 Sacramento Valley Fall Burn was down considerably over
previous years. The program ran from September 17 through November 12 and saw several
weather fronts create favorable conditions for burning. A forest fire in Butte County,
however, hampered air quality and illustrated the complexities involved in managing the
air quality of the Sacramento Valley.
Fall Burn in Review
The official start of the fall burn program was Sept. 17, under weather typical for early fall in the Sacramento Valleysunny, dry and very warm. Burning began slowly under stable weather conditions until the first of three rainstorms swept through the region only a week later. As a cold front approached on Sept. 24, program managers sought to take advantage of this change favorable for burning and allocated 3,500 acres, 2,137 acres of which were successfully burned before a half inch of rain slowed the burning process for the next several days.
October began very warm, cooled in the middle of the month, and ended on a rainy note. Record high temperatures were set during the first week. High pressure kept the atmosphere very stable much of the month, making for poor atmospheric dispersion of smoke. Strong north winds limited burning Oct. 1213. On Oct. 24. a forest fire in southeastern Butte County added to the smoke and particulate matter in the air basin. Very poor air quality, primarily from this forest fire, resulted in a no burn day Oct. 26. Smoke from this wildfire contributed significantly to local air pollution on the east side of the Valley.
Citizen complaints were recorded in Yuba County and the Northern Sierra Air Quality Management District region on Oct. 25 and 26. The forest fire to the north during this period most likely contributed to these complaints.
A welcome change in the weather took place Oct. 27 that allowed three successive days of active rice field burning. From October 27 through October 29 a total of 16,600 acres were allocated for burning and 14, 584 acres were actually burned. The largest burn day of the fall was Oct. 29 when 6,064 acres were burned.
The second rainy period arrived in the Valley Oct. 30. With nearly an inch of rain falling in two days, rice fields were left fairly soggy and little straw burned until Nov. 5. Poor air quality shut things down again on Nov 89. Burning resumed Nov. 10 but only for a short period. The rain brought a halt to the organized portion of the program on Nov. 12.
It was common last year for considerably less acreage to be burned than was allocated. For the entire season, an average of 2,331 acres were allocated but only 1,014 acres, on average, were burned each day. Total rice acreage burned in the fall burn program was 43,680 acres, the lowest amount in many years. Other agricultural burning totaled 15,009 acres.
About the Fall Burn Program
An agricultural burning programthe Sacramento Valley Agricultural Burn Planhas been in place in the Sacramento Valley since 1981. It has done an outstanding job of minimizing air quality impacts by managing the burning activities based on weather conditions and existing air quality on a specific day. When the atmosphere can disperse the smoke from fires efficiently, burning activity is increased. Conversely, when the atmosphere cannot disperse smoke efficiently and/or the air quality is too marginal, burning is limited or halted altogether. Existing law limits burning to the lesser of 25 percent of each growers planted acreage or a total of 125,000 acres throughout the Sacramento Valley. As of last year only burning for disease control is allowed up to these limits.
The Basinwide Air Pollution Control Council, made up of an elected official from the board of directors of each of the nine air pollution control districts in the air basin, develops the Sacramento Valley Agricultural Burn Plan, which is reviewed by the state Air Resources Board (ARB). Under the plan, the ARB allocates a specific number of acres that can be burned on a given day based on the air quality and Valley weather conditions. A central computer operator then allocates acreage for each county to distribute to local growers.
Once again the program functioned admirably in 2001. Other factors, such as forest fires, automobile traffic and residential burning can and do impact the air quality of the Sacramento Valley more significantly than agricultural burning.