By Myrna Trauntvein
TN Correspondent
Juab County does get extra precipitation from cloud seeding and it doesn’t rob those downwind from the seeding. After hearing a presentation by officials from the Utah Water Resources Development Corporation (UWRDC), the State of Utah Department of Natural Resources Division of Water Resources and the North American Weather Consultants, Juab County Commissioners decided that the cloud seeding program they had been participating in was worth continuing participation. “I make the motion that we do participate,” said Clinton Painter, commissioner. Bryce Jackson, president of UWRCD, Jake M. Serago, PE, water resources engineer with the state, and Stephanie Beall, North American Weather Consultants (NAWC) Meteorologist made the presentation. “Juab County has participated in a central/southern Utah winter cloud seeding program most winter seasons since 1974,” said Beall. “Does it work?” asked Byron Woodland, county commission chairman. “NAWC prepares an operations report each summer following the conduct of the central/southern cloud seeding program,” said Beall. “These evaluations have consistently shown increases in precipitation in the intended target areas.” The average increase, she said, in December through March precipitation in the central/southern Utah program, has been 12 percent.” The annual Juab County funding level of the central/southern Utah cloud seeding program is approximately $6,000. This amount is matched by the state. “If the estimated increase in average streamflow, 3,000 acre feet, is divided by Juab County’s annual cost, the cost of the increased streamflow is approximately $1.95 per acre-foot,” said Beall. “This value represents very inexpensive supplemental water for agricultural and culinary uses within the county.” “NAWC looked specifically at the potential impacts of cloud seeding in Juab County,” said Beall. “Since most entities that sponsor winter cloud seeding programs are interested in streamflow for the Salt Creek gauge site, NAWC obtained USGS records of stream flow for Nephi.” An average runoff value of 25,000 acre-feet was calculated for this site by Dr. Norman Stauffer with the Division of Water Resources in a 2000 publication that estimated increases in streamflow in Utah due to cloud seeding. Long-term program evaluations by NAWC have yielded an estimate of 13 percent estimated increase in December through March precipitation due to cloud seeding. The resulting percentage increases for stream flow due to cloud seeding are higher than the percentage increases for seasonal precipitation due to the fact that a relatively fixed amount of winter season precipitation is used to recharge groundwater or for vegetation requirements, evaporation, etc. and the increases in precipitation can be considered an excess since the base recharge requirements have been met. “Applying a 12 percent increase to the average annual runoff value (25,000) yields 3,000 acre-feet of estimated stream flow increase due to seeding in an average year,” said Beall. “This is the only stream that has a stream gauge in Juab County expected to be impacted by the cloud seeding program.” There are other small streams that may be impacted in the county but none of these have established stream gauges therefore the 3,000 acre-feet is a conservative estimate, she said. Another concern of the commission was that cloud seeding may deprive communities downwind of the seeding. “A similar evaluation of precipitation falling in a lower elevation region downwind of the intended target area indicates an average excess of approximately 15 percent,” said Jackson. “They are benefiting from the cloud seeding as well.” One such example, he said, was based on a cloud seeding project that ended up giving snow to Denver. “We had taken all we could get here but there was still enough precipitation left to benefit them.” Utah had a snow-based economy, Serago said. Snow on the mountains was like a reservoir for the valleys and the melted snow turned into water that fed dams and restored ground water reservoirs. Serago said that a cloud seeding program has been conducted in portions of Utah every winter season since the 1973-74 season, except for 1983-84. “The goal of this program has been to augment naturally occurring snowpack in the higher elevation regions,” said Serago. “ The Cloud Seeding to Increase Precipitation Act of 1973, authorized the Utah Board of Water Resources as the policy making body for the Utah Division of Water Resources.” “The UWRCD has contracted with NAWC, with headquarters in Sandy, to conduct these programs and worked with the Division of Water Resources in obtaining the cost share funding,” said Beall. This program has been administered by a non-profit organization known as the Utah Water Resources Development Corporation. “The State of Utah, through the Division of Water Resources, has provided financial cost sharing assistance to the participating counties since the 1975-76 winter season,” said Serago. He said that Juab County would also receive money from the state that was available on a cost-sharing basis. “Beginning in 1976,” said Beall, the State of Utah, began cost sharing with local entities that were contracting for cloud seeding programs. In recent years, this cost sharing has been 50 percent of the program costs.” Beall showed a map that provided the locations of silver iodide generator locations in Juab County. “The target area in Juab County is the higher elevation watersheds on the east side of the county.” Those areas included the Canyon and San Pitch Mountains which produce most of the surface stream flow in the county. “North American Weather Consultants (NAWC) has been the contractor selected to conduct this program by the Utah Water Resources Development Corporation each winter of operation, said Beall. “There is sufficient supercooled water present in storms over Utah to permit seeding material to nucleate and grow additional precipitation,” said Jackson. Seeding material released from ground generators can reach seedable locations in sufficiently dilute but wide-spread concentrations to affect a significant portion of a storm.
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