Posts Tagged: water quality

Lake Tahoe clarity not impaired by Angora Fire

The clarity of the Sierra Nevada's largest alpine lake - Lake Tahoe - was not significantly impaired in the aftermath of the 2007 Angora Fire, according to a story in the Reno Gazette-Journal.

Proactive steps taken by the U.S. Forest Service to reseed the land charred by the fire, which burned 254 homes and blackened 3,000 acres, were credited for helping stave off erosion that could have clouded the lake.

The story was prompted by the release in August of the results of an annual survey of Lake Tahoe clarity by the UC Davis Tahoe Environmental Research Center. TERC reported that the lake was clear to an average depth of 68.1 feet in 2009, holding steady for the ninth year in a row. However, the lake is considerably less clear than it was when researchers first began tracking its clarity in 1968, when it was clear to an average depth of 102.4 feet.

"There was concern that erosion from the (Angora) burn area would get into the lake and cause problems," TERC director Geoff Schladow told the Reno paper. "But we found that the impact from the fire was negligible, which was a great relief for us. All we can say is we may have dodged a bullet on that one."

The newspaper also presented other findings from the 2009 TERC report:

• Invasive quagga mussels were found on 10 boats inspected by Tahoe management agencies as they headed for the lake.
• More precipitation fell as rain and less as snow.
• Algae attached to rocks and docks increased along the northeast shoreline.
• The amount of water-clouding particles and nutrients reaching the lake by west-side streams increased as precipitation rose from previous years.

Lake Tahoe clarity holding steady. (Photo by Roy Tennant, freelargephotos.com)

Scientists help clean lake in Guatemala

Armed with decades of knowledge gleaned from research on Lake Tahoe, scientists from UC Davis, University of Nevada-Reno and Arizona State are helping tackle pollution on a remarkably similar body of water in Guatemala, according to a UNR news release.

The water in Lake Atitlan is contaminated with waste water and watershed runoff, spurring algae growth and providing suitable conditions for bacteria and pathogens.

UC Davis wetlands ecologist Eliska Rejmankova initiated the project, aimed at training Guatemalan students to protect the water in what Global Nature Fund in 2009 designated its "Threatened Lake of the Year."

"We want to work with these groups and help train Guatemalan students to develop local capacity to conserve one of the most beautiful highland tropical lakes in the world," Rejmankova was quoted in the release. "We want to work with local scientists to develop alternative strategies, based around the idea that the solution to the algae problem is to address the sources of nutrient loading into the lake, so water going into the lake will be as clean as possible."

The UC Davis members of the team, lead by Rejmankova, conducted near-shore sampling of invertebrates, algae, water, sediments, and plants, the news release said.

The environmental blogs Treehugger and Red Orbit picked up the story.

Researchers and students examine a sediment core sample from the bottom of Lake Atitlan.

Forest Service works with UC to ensure water quality

U.S. Forest Service regional forester Randy Moore said the agency and its collaborators take the quality of high Sierra water seriously, according to an op-ed article that ran in the Sacramento Bee over the weekend.

The op-ed came after a May 1 Sac Bee editorial encouraging the Forest Service to limit grazing to lower elevations.

Moore wrote that the Forest Service is working with the State Water Resources Control Board to develop a water quality management plan for California national forests. The plan will establish best-management practices for controlling non-point source pollution like that produced by grazing cattle.

To develop the practices, Moore said the agencies are looking at a large body of peer-reviewed literature examining the relationship between livestock and water quality. The studies were conducted by respected environmental researchers, he wrote, specifically naming UC Davis Cooperative Extension specialists Ken Tate and Rob Atwill.

UC Davis researchers have offered to work with the Forest Service to design monitoring and research that is scientifically credible and provides information that will ensure the safety and quality of watersheds, the op-ed says.

A lake in the high Sierra. (Photo: Mike Poe.)

High Sierra not the place for cattle, scientists say

A UC Davis emergency room doctor and the director of the UC Davis Tahoe Research Center have launched a publicity campaign calling for cattle grazing to be suspended in the high Sierra, according to a story in Sunday's Sacramento Bee.

The article, billed as a "Bee exclusive" and written by Tom Knudson, said the doctor, an avid backpacker, took hundreds of water samples from pristine streams and lakes in the Sierras. He found that high-elevation water bodies on land managed by the Forest Service had bacterial contamination high enough to sicken hikers with Giardia, E. coli and other diseases. However, at high elevations in Yosemite and Sequoia/Kings Canyon National Parks, where cattle do not graze, the lakes and streams were pollution-free.

Doctor Robert Derlet and Tahoe Research Center director Charles Goldman believe cattle should be moved to lower elevations and that high Sierra areas now managed by the Forest Service should be converted into national parks.

"At one time, cattle were important for developing civilization here," Derlet was quoted in the story. "But now, with 40 million people in California, the Sierra is not for cattle. It's for water. We need water more than Big Macs."

The story also quoted Anne Yose, the regional rangeland program manager for the Forest Service. She said Forest Service studies show that "we can still successfully manage livestock and maintain water quality."

However, she also acknowledged in the story that it is "logistically really, really difficult" for the Forest Service to sample backcountry water.

The article said Derlet devised an insulating nylon kit and procedure for keeping water samples fresh, which includes rushing back to his car, icing the samples in a cooler and driving directly to a UC Davis lab.

Cattle grazing on low lands.

Riverside won't use treated water to irrigate citrus

Reversing course, the City of Riverside has decided it will not supply treated wastewater to irrigate citrus trees in a green belt and on the UC Riverside campus, according to a story that ran over the weekend in the Riverside Press-Enterprise.

The idea was dropped after grower Andy Wilson raised objections to the plan saying the reclaimed water contains trace amounts of boron and sodium, which could accumulate in the soil and eventually kill trees. Instead, the city will sponsor a 10- to 15-year UC Riverside study to learn how boron affects trees and fruit.

According to the article, written by David Danelski, UCR soil chemistry professor Christopher Amrhein said Wilson had good reason to be concerned about the city's plan divert fresh water from the Gage and Riverside canals and replace it with the recycled wastewater from the city's sewage treatment plant.

"We basically told (city officials), 'We can't take your reclaimed water,' " Amrhein was quoted.

The city has used UC Davis agricultural engineering professor Mark Grismer as a consultant to counter arguments by UCR citrus experts that recycled water would harm the trees. The city's recycled water project is still in the works. The reclaimed water will be used to irrigate Martha McLean Anza Narrows Park, Fairmont Park and the future Tequesquite Park, and could also be used to recharge aquifers.

Irrigating citrus.

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