Listed below are the local agencies that are members of the UMRWA Joint Powers Authority.

• Alpine County
• Alpine Couty Water Agency
• Amador County
• Amador Water Agency
• Calaveras County
• Calaveras County Water District
• Calaveras Public Utility District
• East Bay Municipal Utility District
• Jackson Valley Irrigation District

UMRWA Affiliate Organizations include the following. 

• Alpine Watershed Group
• Amador Calaveras Consensus Group
• Foothill Conservancy
• Motherlode Land Trust
• Mule Deer Foundation
• Stewardship Through Education