Near San Diego, the nearly $50 million construction of another leg of border fencing between the United States and Mexico appears to be the culprit in some serious sediment runoff. Of note, locals point out, a valley area known as “Smuggler’s Gulch” is being filled in with soil cut for the project. The 150-ft-high berm will support access roads and a stretch of fencing, but in the meantime is simply releasing soil into the water. Construction is not the only problem, though, as the site officials point out. The area is also plagued by sudden, heavy rains and illegal dumping in channels.