The Stream, July 19: Heavy Irrigation Causes Land Subsidence, Arsenic Contamination in California’s Central Valley

The Global Rundown

Large-scale irrigation causes California’s Central Valley to sink, as well as polluting drinking water with arsenic. Officials in Bangalore, India, fail to keep “rejuvenated” lakes clean. As private springs run dry, drought-stricken Scotland provides water to citizens not connected to the public supply. Officials fear an algal toxin has tainted drinking water in a southern Iowa community. A sweltering summer and a lack of precipitation in the Arctic Circle prompts an irregular number of wildfires.

“This is definitely the worst year in recent times for forest fires. Whilst we get them every year, 2018 is shaping up to be excessive.” –Mike Peacock, a Swedish university researcher, in reference to the unprecedented number of wildfires raging in the Arctic Circle. High temperatures and minimal precipitation have fueled at least 11 blazes in the northern region. The Guardian

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By The Numbers

4 percent Proportion of Scottish citizens who are not connected to the country’s public water system. Many private springs and wells, however, are running dry in the midst of an unusually warm summer. In response, the government is providing emergency water to affected residents. BBC

20 Lakes that have been rejuvenated in the Hebbal Valley near Bangalore, India. Despite the rejuvenation efforts, a report by the Indian Institute of Sciences showed that only 3 of the lakes are currently in good condition. The remainder have been neglected, filling with sewage, garbage, and other pollutants. The Hindu

In context: Booming Infrastructure Poisons Bangalore’s Lakes, Depletes Groundwater.

Science, Studies, And Reports

Land subsidence and arsenic-polluted water in California’s Central Valley are likely linked, according to a new study by Stanford University. Hundreds of crops are grown in the valley, requiring massive amounts of irrigation. Farmers must draw heavily from underground aquifers, which leads to land subsidence and changes in water pressure. In turn, the changes in pressure can suck arsenic out of clay layers–which then leaches into groundwater and ultimately ends up in the region’s drinking supply. The Guardian

In context: Map: Central Valley’s Arsenic Contamination (2006-2013).

On The Radar

Officials suspect that the drinking water supplies of Greenfield, Iowa, may be tainted by microcystin, an algal toxin. Residents have been warned to avoid tap water while the water is tested for the toxin. U.S. News & World Report

In context: Regulators Will Soon Know A Lot More About Algal Toxins in U.S. Drinking Water.

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