A Saltwater Wedge Is Moving Up The Mississippi RiverAs the Mississippi River drops to one of its lowest levels in recent history, the U.S. Army Corps of Engineers said salt water from the Gulf of Mexico could threaten drinking water as far north as New Orleans’ French Quarter if no action is taken.On Friday, the Corps announced plans to avoid that scenario by building upon an existing underwater barrier that has been in place to block the progression of salt water from intruding farther upriver since July. At its current height, the Corps expects the salt water creeping up the bottom of the Mississippi River to overtop the barrier later this week, sometime around Sept. 22.If that were to happen, the salt water would begin affecting drinking water in Belle Chasse by early October.To read more, visit sciencefriday.com.Kenya’s Geothermal Boom Could Help Power AfricaBeneath Kenya, the African tectonic plate is splitting in two. That cleave creates hydrothermal vents, ripe for harnessing geothermal energy. This is a renewable source of energy derived from hot water that bubbles up from deep underground. When it comes to the surface, it turns into steam. That steam can be used to spin a turbine connected to a generator, and voilá: electricity.Kenya began to tap into this natural supply in the 1950s, and now the East African nation is the seventh largest geothermal energy producer in the world. The Kenyan government has said that the country’s untapped resources are enough to meet its peak energy demands five times over. That’s a big deal on a continent where more than 40% of people lack electricity.Joining guest host Flora Lichtman to talk about this is Geoffrey Kamadi, a freelance science journalist based in Nairobi, Kenya.  To stay updated on all-things-science, sign up for Science Friday's newsletters.Transcripts for each segment will be available the week after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.