A 15-year water supply agreement between agencies in Sonoma and Marin counties has received final approval. Under the agreement, the Marin Municipal Water District will pay $12.5 million to the Sonoma County Water Agency to boost regional drought resiliency. The agreement replaces previous contracts and establishes the terms for how Russian River water is delivered to Marin County through 2040. Marin Municipal Water District officials approved the contract at a meeting in August. The board governing the Sonoma County agency solidified the agreement on Tuesday.