The U.S. and Canada said Thursday they have agreed to update a six-decade-old treaty that governs the use of one of North America’s largest rivers, the Columbia, with provisions that officials said would provide for effective flood control, irrigation, and hydropower generation and sharing between the countries.

The “agreement in principle,” reached after six years of talks, provides a framework for updating the Columbia River Treaty. It calls for the U.S. to keep more of the power generated by its dams while improving cooperation between the Bonneville Power Administration, which markets power from dams in the northwestern U.S., and Canadian utilities, to help avoid blackouts.