While much of the world, including the U.S. West, struggles over how to maintain a sustainable supply of water, communities across Clark County on Friday received a reassuring message: Your access to that crucial and finite resource is guaranteed for decades.

That was the upshot of an announcement by the Washington state Department of Ecology that it has approved a major new water right for Clark Public Utilities, as well as a smaller, but no less important, one for the city of Ridgefield.

The permit for the right to tap an underground water source will enable Clark Public Utilities to at least double its capacity to provide water to residential and business customers in unincorporated areas, including everywhere from Hazel Dell and Salmon Creek to Brush Prairie and La Center. The utility currently provides water to about 30,000 homes and businesses.

In the works since 2001, the utility’s new water permit — granted by the Ecology department under state laws dating back to 1917 — is the largest one in recent state history. “Based on my institutional knowledge, there aren’t many water rights in the, say, last 10 years that have been this large,” said Mike Gallagher, regional water resources manager for the Ecology department.

The utility’s permit is tied to a complex deal involving state and utility officials, a large toxic cleanup project by the Port of Vancouver, and years of planning and water testing by watershed experts.