Volunteer registration is now open for the 31st Annual River Rally Clean-Up and Environmental Expo scheduled for Saturday, September 19, from 8 to 11 a.m. The Santa Clara River, which runs through the Santa Clarita Valley, is one of the last natural, free-flowing river systems in Southern California. The annual River Rally event brings together approximately 1,200 volunteers yearly to help protect this important resource. The River Rally is a perfect volunteer opportunity for individuals, families, clubs, scout troops and businesses to make a difference in the community. For more information on the 31st Annual River Rally and Environmental Expo or to register, please visit GreenSantaClarita.com or call (661) 286-4098.