In science news this week: Follow the flow: The state of the San Lorenzo River; Ancient groundwater may not be as clean as once thought; Research suggests climate change likely to cause significant shift in Colorado River vegetation; Mystery of the missing mercury at the Great Salt Lake; Rising water temperatures endanger health of coastal ecosystems, study finds; and Trillions of plastic bits, swept up by the current, are littering arctic waters Follow the flow: The state of the San Lorenzo River: “Flow has long shaped the relationship between Santa Cruz, California, and the San Lorenzo River, which runs through the city. The memorable “Christmas Flood” of 1955 sent 10 feet of water surging through downtown Santa Cruz, and prompted the construction of flood control levees that channelized the river. A spate of heavy winter storms earlier this year put San Lorenzo River flow back on people’s minds, with February flows hitting levels nearly 30 times greater than the long-term average. Fittingly, flow was also the focus of this year’s State of the San Lorenzo River symposium, which FISHBIO’s Santa Cruz staff attended earlier this year. The series of talks highlighted where the San Lorenzo River’s water comes from, the influences of flow on fish, and challenges in the watershed. … ” Read more from FishBio here: Follow the flow: The state of the San Lorenzo River Ancient groundwater may not be as clean as once thought: “Most of the groundwater that is accessible by deep wells is old, but still vulnerable to modern contamination, reports a study published today in Nature Geoscience by researchers from University of Calgary, Stanford, and other institutions. The world’s groundwater provides drinking water and irrigation for billions of people around the world. Some of this groundwater is young and easily affected by pollution and changes in climate. But much more is old groundwater that has been stored beneath the Earth’s surface for thousands of years. Old groundwater is more difficult to…