ACWA Members Tour Mount Tam Watershed by Dennis Mayo Sep 7, 2017 Voices on Water ACWA Region 1 and the Marin Municipal Water District hosted a tour of the Mount Tam watershed on August 4. The tour included visits to the San Geronimo Treatment Plant, Lake Lagunitas, the Alpine Reservoir Dam, the west peak of Mount Tam, and attracted nearly 30 participants. The day began at the headquarters for the Marin Municipal Water District in Corte Madera, where members were welcomed by Krishna Kumar, General Manager of MMWD and ACWA President, Kathleen Tiegs. Once the welcome was complete, Lon Peterson, Communications and Outreach Manager, MMWD, took the lead as attendees headed to the San Geronimo Water Treatment Plant. Upon arrival, attendees were led by plant management through the entire water cycle of the facility to include observing large water transfers through their filtration system. On their way to the top of the watershed, attendees also toured Lake Lagunitas. While at Lake Lagunitas, attendees received ACWA updates from ACWA President, Kathleen Tiegs, and Vice President, Brent Hastey. Attendees also had the opportunity to view Lake Lagunitas which is the oldest one of seven reservoirs in the watershed supplying potable water to MMWD, built in 1872 and capable of supplying 350 acre feet. Continuing on the reservoir theme, attendees continued up the watershed to the Alpine Reservoir Dam where MMWD Assistant Engineer Lucy Croy gave a short history of the dam and disclosed that this is the only concrete dam in the watershed, was originally completed in 1918, and has been added onto twice (1924, and 1941) to bring the total dam height to 143 feet and a capacity of almost 9,000 acre feet. The next leg of the tour was touring the west peak of Mount Tam. While there, MMWD Ranger Matt Cerkel spoke of the restoration processes to remedy the leveling of the west peak in the 1950s by the U.S. Air Force to erect the Mill Valley Air Station to guard against a cold war nuclear attack, the removal of remaining infrastructure, and replacement of removed soils. This is a collaborative effort between MMWD and the Tamalpais Lands Collaborative to create a more focused design, restore habitats, and is projected to be implemented in 2020. Wrapping up an information filled day, attendees returned to the MMWD headquarters to conclude the tour. I would like to thank the Marin Municipal Water District for hosting the event, specifically ACWA Region 1 Board Member and MMWD Environmental and Engineering Services Manager Michael Ban and MMWD Communications and Outreach Manager Lon Peterson for arranging the tour of their watershed and guiding us throughout the day – thank you! For upcoming information about ACWA Region 1 activities, please visit www.acwa.com.