The Salt River is seasonal. It can get to the point of causing flooding (e.g. winter '77-'78). Tempe Town Lake was done in the 1990s, mainly for recreation and filled with water from the Colorado River, but I wonder if it also recharges the local aquifer and might be available to give some "cushion" during a very rainy winter. One of the street bridges over it was built in the 1930s, and another in the 1990s to increase traffic capacity. In winter '77-'78 the 1930s bridge was one of just two that were open the whole time of the flooding (Central Avenue in Phoenix was intact but intermittent). The parks, streets, and trails and near the lake are sometimes used for running events (not this time of the year, obviously!).