Autumn is generally a good time of the year to explore San Diego County on the hiking trails - the air is crisp, the heat not so relenting, and you might even catch some leaves changing colors. One of the more accessible places for a quick day hike for locals is Mission Trails Regional Park. And within the massive Mission Trails Park, is a hidden gem that also is a genuine part of San Diego's history: the Old Mission Dam.
When Franciscan friars moved Mission San Diego de Alcala from the Presidio to its current location in Mission Valley, the friars scouted out a location about six miles upriver as an ideal spot to construct a dam and basin, but construction wasn't begun until 1809. Indian labor from the mission's population was used to build the dam and flume and it was one of the most ambitious in the California mission chain.