Environmental advocates led a hike along the San Diego River in Mission Valley on Sunday morning to build awareness about ongoing efforts to remove invasive species from its banks. The San Diego River Park Foundation hosted the hour-long jaunt, showing off a dramatically improved section of the river located in the 52-acre Mission Valley Preserve. About a dozen folks in wide-brimmed hats and toting water bottles listened as Marina Varano, outreach associate with the foundation, educated the crowd about efforts to restore the riparian habitat.