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Cloud seeding forum held in Chester

M. Kate West
Chester Editor
6/1/2011

The forum hosted by the Almanor Basin Watershed Advisory Committee (ABWAC) Wednesday, May 25, fielded a panel of six scientists in response to community concerns about cloud seeding in the Lake Almanor Basin.

The issue surfaced when Basin resident Lisa Marcus, at the urging of ABWAC member David Durkin, attended the March 9 committee meeting. During the public comment period she read a summary of her concerns that included questions she wanted answered by Pacific, Gas and Electric Company.

Opening the forum, ABWAC chair Ryan Burnett welcomed guests, provided an overview of the agenda, introduced the panel and facilitated the question and answer period between the audience and the panel.

Panel members included Don A. Griffith, Byron Marler, Charles White, Dan Tormey, Gina Johnston and Arlen Huggins.

Throughout the course of the forum, the audience was exposed to a variety of scientific data about cloud seeding and the breakdown of chemicals in the process.

Emerging data

Mr. Don A. Griffith, of North American Weather Consultants, Sandy, Utah, was the first speaker and provided the following information:

—Cloud seeding has been occurring in Lake Almanor since 1953.

—There are 13 cloud seeding programs in California. PG&E operates two, on the watersheds of Lake Almanor and the upper Mokelumne River. Other program operators include the Desert Research Institute, Sacramento Municipal Utility District, Turlock and Modesto Irrigation District, Southern California Edison, the city of Los Angeles, the North Kern Water Storage District, the Kaweah Delta Water Conservation District and the coastal counties of Los Angeles and Santa Barbara.

—Weather modification programs operate throughout the Western United States in Utah, Nevada, Colorado, New Mexico, North Dakota, Wyoming, Kansas, Oklahoma and Texas.

—Canada and approximately 40 – 50 other countries around the world are currently operating weather modification programs.

Griffith additionally provided historical data on weather modification programs from the mid-1940s experiments to the operational programs of the 1950s and forward.

He said different states used weather modification for different reasons; some participate for precipitation or rainfall augmentation, others snowpack augmentation. In some Midwest states, the process is used for both rainfall augmentation and hail suppression.

Cloud seeding described

Griffith talked about how cloud seeding works and the types of programs that are used.

The type of program used in the Lake Almanor Basin is referred to as a “winter orographic cloud seeding methodology.”

Griffith said orographic means “over the mountains.”

In this method, Griffith explained the four-step process:

—A minute amount of silver iodide is sprayed across a propane flame.

—The silver iodide particles then rise into the clouds.

—The silver iodide causes cloud moisture to freeze and create ice crystals.

—The ice crystals then grow big enough to fall as snow.

“The winter orographic program is designed to increase snowfall,” Griffith said.

He listed other program types and purposes and said winter and summer programs both are designed to increase rainfall.

“Hail mitigation programs are designed to reduce damage from hailstorms. There are also cold fog programs designed to increase visibility at airports,” Griffith added.

Seeding agents and modes

Silver iodide, dry ice and propane are used in cloud seeding operations.

Griffith said there are two seeding (distribution) modes: ground based and airborne.

The ground-based modes include manually operated silver iodide generators, remotely operated silver iodide generators and remotely operated propane dispensers.

Airborne modes include burn-in-place silver iodide flares, droppable silver iodide flares, acetone-silver iodide generators and dry ice.

He said the generators are located on the west side of mountains.

Results and opinion

“There have been a number of studies that examine the potential for the creation of negative environmental impacts associated with the conduct of winter cloud seeding programs. Several of these studies, which involved both office and field work, were supported by the Bureau of Reclamation office in Denver under their ‘Project Skywater’ program,” Griffith said.

After listing a number of lengthy studies completed by different groups between 1975 and 1980, in Utah, Colorado, southern Wyoming and at the American River drainage in California, he said, “These studies concluded that significant environmental effects due to the possible conduct of cloud-seeding programs in these areas were not expected to occur.”

He next read the July 2009 position statement of the Water Modification Association (WMA) on the environmental impact of using silver iodide as a cloud seeding agent.

“The potential environmental impacts of cloud seeding programs using silver iodide have been studied since the 1960s. These studies have all concluded that ice-nucleating agents, specifically silver iodide as used in cloud seeding, represent a negligible environmental hazard.

“In summary, the published scientific literature clearly shows no environmentally harmful effects arising from cloud seeding with silver iodide aerosols have been observed, nor would be expected to occur. Based on this work, the WMA finds that silver iodide is environmental safe as it is currently being used in the conduct of cloud seeding programs.”

Among the references offered by Griffith was the WMA website weathermodification.org.

Seeding specific to Almanor

PG&E Consultant Byron Marler offered the second presentation of the evening and confined his data to the Lake Almanor Basin.

He said there were four goals to the cloud seeding program:

—Augment snowfall in the higher elevations of the target watersheds.

—Increase percolation into aquifers to augment spring fed flows into the Lake Almanor Basin.

—Augment snowpack melt for hydroelectric power production during the spring and summer months and also benefit water supply.

—To have a 3 – 7 percent increase of water in the target watersheds.

Marler described the Lake Almanor cloud-seeding program and said, “The target area is located 500 square miles above Lake Almanor and contains 10 ground-based radio controlled seeding generators.”

He said no airplane seeding is done.

When seeding occurs

Marler said seeding operations happen only during cold, snow producing storms that occur during the months of November through May.

He also said, “Silver iodide is a powerful tool, with a leveraging effect used in 10 – 11 programs each year along the Sierra Nevada. It’s not a new thing; it’s been going on a very long time. These are some of the oldest programs in the world.”

Other seeding facts given by Marler were:

—Suspension criteria are incorporated into the project procedures

—PG&E meteorologists monitor weather over the watersheds and control seeding treatments based on conditions meeting certain temperatures and wind conditions.

—Seeding generators are monitored and controlled by radio signal.

—Each generator emits silver iodide at 21.5 grams per hour during selected storm periods.

—Typically, the Lake Almanor program releases less than 200 pounds per year of seeding materials to the atmosphere.

Properties of silver iodide

In talking about cloud seeding with silver iodide, Marler said, “PG&E seeding units release a plume of hot gases and very small particles. Each particle contains silver iodide.”

He said the “particles are not carcinogenic and … they have extremely low solubility in water.”

He also said the particles remain solid in the air, cloud and precipitation.

“The particles do not ionize to produce Ag+ under ambient environmental conditions,” Marler said.

His presentation reports that silver iodide, as used in cloud seeding, contains extremely small concentrations (measured in the parts per trillion range) and poses no hazard.

He also talked about the three-year Lake Almanor water, sediment and aquatic species tissue study as regards total silver.

During that time, 208 water samples, four sediment samples and the tissues from seven fish and one crayfish were tested.

He said the results from that study reported:

—Total silver concentrations were below the reporting limit for all stations and testing months.

—Lab method detection limits silver in water varied by year with the lowest in 2002-03. All water sample concentrations were below protection guidelines for humans, plants and animals. (Marler referenced Appendix A in the Cardno Entrix report: Geochemistry and impacts of silver iodide use in cloud seeding.)

—Sediments: No detectable levels of silver were found in sediment samples.

—Biological tissues: All concentrations were low.

Marler also talked about studies that have addressed environmental impacts and concerns relating to cloud seeding with silver iodide.

In summary he said, “Environmental impact studies on projects using silver iodide generators similar to those used in PG&E projects resulted in findings of no significant impacts.

“Silver concentration measured in snow, water, soils and lake sediments are far below thresholds of concern for humans, animals, fish, insects and plants and are not shown to affect endangered or threatened species of plants or wildlife or their habitats.

“In summary, my take home, there has been high resolution analysis of water, sediment and biological samples from areas subjected to long-term, 50-plus years cloud seeding programs, specially PG&E programs at Mokelumne and Lake Almanor.”

He said the analysis supported the following:

—The amount of silver iodide released to the atmosphere in cloud seeding is small and even after many years of cloud seeding operations the resulting environmental concentrations are very small to non-detectable.

—Based on the monitoring results of seeding chemicals being extremely low in water and sediments, continued cloud seeding operations would not result in any significant increase in silver concentrations in the watershed.

Marler said benefits derived from cloud seeding include the making of more water; reducing, reversing warming climate impacts on local snowpack; and better grasses and better grazing for livestock and native animals.

More water is available for streams, which, in turn, benefits aquatic life. More water in streams and lakes benefits people and recreation, Marler said.

Q&A and other comment

Marcus, who was in attendance, said she was seeking answers as to whether or not silver iodide in nano particle form is harmful. She said she is pursuing the issue as an advocate on behalf of children that play, drink, eat and breathe on and around the cloud seeded soil and snows of Lake Almanor.

“My first question: Is the silver iodide in nano particle form?” she asked.

Tormey responded and said, “When the embryo forms out of the gaseous state, they grow to a nucleolus. Yes, they are small particles.”

Marcus said she believed the particles were toxic and could be absorbed through the skin and lungs.

Tormey in turn advised Marcus that silver iodide was very different from the nano particle ionic and elemental silver.

He also spoke to the long-time use of silver in consumer products and said the manufacture of nano particles is a relatively new thing; that when you look at the effects in nano size, a nano particle is more charged then a larger scale product of the same compound.

Tormey repeatedly supported the previous statements that silver iodine levels in cloud seeding were not toxic.

Charles Plopper offered the comment that he didn’t believe Torney could say things were not toxic if levels fell below detection level.

Susanville resident Douglas Singer wanted to know if the cloud seeding operation at Lake Almanor was the reason the water at Eagle Lake is low.

“Is this system taking away from the watershed of that area?” he asked.

He also asked, “There are tornadoes that hit the East Coast and today there are a couple of tornadoes in Chico doing damage — are we messing with the atmosphere?”

Griffith responded, “The particles are so diluted they can’t do much more than an hour’s travel from the generator. More formed particles can travel 100 miles.”

He said the cloud seeding during storms and the accompanying wind would likely benefit the area.

Arlen Huggins also responded, “Cloud seeding has no impact on storms, no dynamic effect on large scale weather patterns. Tornados are rare in California but not unknown phenomena.”

“I read that the chemicals are stored on the decks in the woods. Who is mixing the chemicals, a licensed person or an amateur?” asked Margie Strite.

She was advised the chemicals were purchased from a chemical company, that they were premixed, delivered by the drum and pumped directly into the generator.

She questioned the use of acetone in the process.

Marler told her the acetone burns off and does not go up into the atmosphere.

Torney added that the temperature at time of combustion causes a breakdown; that the combustion changes acetone to carbon dioxide and water.

“Pretty much the same as propane,” said Huggins.

Marcus questioned a lack of response from PG&E about her previously submitted questions.

“Your questions that were forwarded to us from both the ABWAC and the Plumas County Board of Supervisors meeting will be answered in full,” PG&E spokesperson Janet Walther said.

She also said, “It’s my hope that many of your questions would be answered during the forum.”

Carol Byers also questioned the effect cloud seeding in the West was having on the rest of the country.

The originations of tornados are well studied and there is no effect on weather patterns Huggins said.

A question was raised as to who regulates cloud seeding in California. The emissions are overseen by local air quality control.

It was also noted that the Northern Sierra Air Management Quality District (NSAMQD) would require an environmental study if the emissions were not below the local threshold.

“All 10 sites have been monitored, the emission is so minute it is no threat,” NSAMQD manager George Ozanich said.

Another guest wanted to know if there was any sort of long-term monitoring in place.

White said ongoing monitoring has been worked into the FERC 2105 Relicensing Agreement signed in 2004.

He said monitoring would take in the North Fork, Belden, Lake Almanor and Butt Valley.

“As soon as we complete the license process monitoring will be done on a regular basis,” White said.

More questions were raised about the properties of silver iodide.

ABWAC member Dick Daniels said, “I’m very curious: Does silver iodide produce free silver or ionic silver?”

“In the studies that have been done, silver iodide is very stable,” Tormey said.

Marcus next showed computer downloads from Airnow.gov that reflected a layering over the Lake Almanor Basin.

“We do have an inversion layer, things do hang around children’s bodies and it’s 10 times more toxic for children; nano technology, it is hanging on us,” she said “You’re dumping a lot on us and you don’t have the right without the studies.”

“Studies of toxicity of silver have never shown any toxic results. Major source of info on humans came from silver nitrate that was used for developing photographs. There’s a large body of studies about high degrees of exposure to silver shows yellowing or bluing of ski,” Tormey said.

He again said silver iodine has no adverse effects to humans.

“I’m hearing little particles of silver iodine are not toxic but the MSDS (Materiel Data Safety Sheet) says it’s highly toxic,” Marcus said.

She then told the panel, “You don’t have enough research and data to say it’s safe. PG&E is the main benefactor of the water.”

“You missed what I said earlier. We seed during storm patterns, which break up inversion layers. Lake Almanor is very clear after storms,” Griffith said.

“Cloud seeding is not regulated by California but we are by EPA. If we are below standards, we are not required to get a permit. PG&E is in compliance with all rules and regulations,” Walther said.

“My point is: Is it safe for children to breathe? There is no data to support whether we should be doing this,” Marcus asked.

Tormey said silver is used in many applications like antimicrobial soaps and tooth fillings.

“The concerns are with the pervasiveness of their use in personal care products,” Tormey replied

“You dumped this stuff directly on us, you are supposed to give us property owners notice — you don’t. Children play outside in fresh snow and get respiratory diseases,” Marcus added.

Torney told Marcus, “You keep coming back to the same thing.”

At this juncture, ABWAC member Aaron Seandel said, “I think we have said all that we can about what we have today. We can’t answer all the questions that have been asked today.”

He also said he hoped the panel members would be available in the future for follow-up questions.

ABWAC Watershed Coordinator Emily Creely tracked all questions that were not answered by the panel.

No next steps or future forum dates were set.


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