DENVER (AP) — The U.S. and Mexico have agreed to expand a far-reaching conservation agreement that governs how they manage the overused Colorado River, which supplies water to millions of people and farms in both nations.

U.S. water district officials say the agreement to be signed Wednesday calls for the United States to invest $31.5 million to improve Mexico's water infrastructure and reduce waste. The water saved would be shared by users in both nations and by environmental projects.

The officials also say Mexico will develop plans for reducing consumption in the event of a river water shortage. That would happen after major U.S. river users finish their own shortage plan.

The International Boundary and Water Commission declined to release a copy of the agreement before Wednesday's signing in New Mexico.