water

Since 1968, researchers have been continuously measuring Lake Tahoe’s famous water clarity and tracking how much it degrades. The degradation of water clarity is caused by runoff and development along the shores of the lake and researchers use it to gauge how healthy the lake is.

New data from UC Davis scientists show that the rate of clarity loss has significantly slowed since 2001, giving residents and scientists interested in the lake cautious optimism that almost $500 million dollars in runoff prevention and treatment may be having a positive effect on the lake.

Image Credit: wmchu on flickr.

Schladow cautioned that the data do not pinpoint a specific cause for the recent improvements, but noted that new modeling results show that runoff of fine particles from both urbanized areas and roadways around the lake are the primary factors that influence clarity levels. Fine particles scatter light and limit how far into the lake we can see.

In addition, Schladow and his UC Davis colleagues cautioned that it is difficult to use data from a small number of years (2001 to 2007) to draw conclusions about when the trend might change from a slowdown in clarity decline to an improvement in clarity. “Only with the commitment to long-term monitoring can we truly evaluate environmental changes over time,” he said.

[Via Physorg]

Arguably Earth’s most dire resource, but only recently receiving any major discussion, is water. As a previous post pointed out the American Southwest is projected to become a drier climate while funding for monitoring and mitigation continues to decrease.

Over the past few years the plight of the Southeast has received a fair bit of press, but overshadowed by Atlanta’s water woes is the brilliance of Clayton County. In the 1980’s the Clayton County Water Authority built a series of wetlands to replace the last step of the water reclamation process. Water entering the sewers continue on to the reclamation facility and pass through the standard filtration systems designed to remove large debris, sediment and any other solids. The purification process is completed by feeding the water into their wetland systems where organisms, from single-celled bacteria to water lilies, do the rest. After the water is gravity-fed through a series of four wetland pools, the water enters their reservoir and is available for reuse. According to a recent story on NPR, of the 26 million gallons used a day in Clayton County, the wetland reclamation process returns 10 million gallons of potable water for future use. Not only are they getting 40% of their water back but the wetlands have created 4,000 acres of green space.

Source: Clayton County Water Authority.

Constructed wetlands are proving to be more efficient, more cost effective, and more environmentally sensitive than comparable secondary treatment methods. The wetlands allow the CCWA to increase its wastewater treatment capacity, while dropping the costs incurred in the process. The cost to build wastewater facilities using constructed wetlands is $4.73 a gallon, compared to nearly $10 a gallon using the more conventional methods.

The Authority’s LAS fields and constructed wetlands are included among the over 4,000 acres of protected green space that will never fall prey to residential or commercial development. This acreage provides for hearty forests and wildlife, not to mention incredible recreational opportunities located in such a close proximity to a major metropolitan city.

In addition to money saved, there have been no complaints about odor and unlike neighboring Atlanta, the residents of Clayton County were never in danger of running out of water during the recent drought.

The National Academy of Sciences released a report today on the impact desalination could have on the United States’ water supplies. The report states that recent technological advances have made desalination a viable option for increasing water supplies and will likely play a role in augmenting our water resource. However, more research into the environmental impacts of desalination are needed.

Desalination plant in Israel. Source: water-technology.net.

Substantial uncertainties remain about the environmental impacts of desalination, the report says. Limited studies suggest that desalination may be less environmentally harmful than many other ways to supplement water — such as diverting freshwater from sensitive ecosystems — but definitive conclusions cannot be made without further research.

Researchers should investigate the extent to which fish and other creatures get trapped in saltwater intake systems in various settings, and seek ways to mitigate this and other impacts. Studies also should examine the long-term ecological effects of disposing of the salt concentrate that remains after desalination in rivers or the sea, a common practice. In addition, environmental evaluations of new desalination plants should be conducted, including ecological monitoring before and after the plant starts operating. The results should be synthesized with existing data in a national assessment that can guide future decision making, the report says.

Desalination also has raised concerns about greenhouse gases because it uses large amounts of energy. Seawater reverse osmosis uses about 10 times more energy than traditional treatment of surface water, for example, and in most cases uses more energy than other ways of augmenting water supplies. Researchers should investigate ways to integrate alternative energy sources — such as the sun, wind, or tides — in order to lower emissions from desalination, the report says.

[Via Eurekalert]

Fresh on the heels of our post yesterday comes this press release from the National Research Council about the prospect of desalination as a potential source to bolster our nation’s water supplies.

As some U.S. regions face water shortages and growing contention over freshwater supplies, some communities are considering adding water through desalination — removing salt either from seawater or the brackish groundwater that underlies large parts of the country.

DESALINATION: A NATIONAL PERSPECTIVE, new from the National Research Council, discusses desalination’s potential for bolstering U.S. water supplies and the advantages and drawbacks of various methods and technologies. The report also identifies existing barriers to desalination’s wider use and outlines research that could help overcome these problems.

The official report will be released tomorrow.

[Via Eurekalert]

During a discussion at lunch on climate change, the Colorado River and the impact on water resources in the Southwest, one of my colleagues reminded me of this article published in the NY Times Magazine in October of 2007. It’s a fascinating (and rather grim) look on the future of water resources in the United States.

Climatologists seem to agree that global warming means the earth will, on average, get wetter. According to Richard Seager, a scientist at Columbia University’s Lamont Doherty Earth Observatory who published a study on the Southwest last spring, more rain and snow will fall in those regions closer to the poles and more precipitation is likely to fall during sporadic, intense storms rather than from smaller, more frequent storms. But many subtropical regions closer to the equator will dry out. The models analyzed by Seager, which focus on regional climate rather than Colorado River flows, show that the Southwest will ultimately be subject to significant atmospheric and weather alterations. More alarming, perhaps, is that the models do not only concern the coming decades; they also address the present. “You know, it’s like, O.K., there’s trouble in the future, but how near in the future does it set in?” he told me. “In this case, it appears that it’s happening right now.” When I asked if the drought in his models would be permanent, he pondered the question for a moment, then replied: “You can’t call it a drought anymore, because it’s going over to a drier climate. No one says the Sahara is in drought.”

I figure this article is apropos, especially because of the recent news of the future of the Colorado River that we posted about last week.

[Via NY Times Magazine]