This is the deepest look Thinkwalks offers into the waterways that once coursed through the Mission District. Do you love thinking about local creeks, wells, puddles and ponds? We’ll discuss their meandering locations and ecology, their implications for the growth of SF, their spring sources and controversial origins. This is a long tour that attracts water history zealots of the best kind. Meet at Adobe Books 3166 16th Street at Guerrero. We’ll end at Clayton and Corbett near bus lines 33 and 37. Steep hills involved. Snacks provided. 3 & 1/2 hours.