The Walton Family Foundation said Monday it will donate $20 million for the restoration and protection of the ever-depleting Colorado River, a move state river basin leaders have called a major step forward for a body of water dangerously close to running dry.

This initial investment represents the first of what the foundation said will amount to more than $100 million by 2020. The foundation has also pledged $15 million to support the restoration of the Mississippi River Delta.

The Colorado River, which serves seven states in the U.S., including drought-torn states like California and Arizona, is drying up. Lake Mead, one of the biggest water suppliers for the river’s lower basin, loses 1.2 million acre feet a year, and Lake Powell, which serves upper basin states like Colorado, isn’t much better, said Matt Rice , director of American Rivers’ Colorado Basin program.

“The Colorado River basin is arguably one of the most important in the country, if not in the world,” Rice said. “And we use more than the river provides. We need to figure out how to do more with less water.”

The $20 million will be allocated toward different groups across the upper and lower river basins, including advocacy organizations such as American Rivers and the National Wildlife Federation.

Ted Kowalski, Colorado River initiative lead for the Walton Family Foundation , said helping sustain the river is crucial to supporting both the environment and the economy.

“If you look at the last 17 years, we’ve seen a remarkable drought,” Kowalski said. “It’s the longest and worst since the turn of the 20th century. It’s one of the worst we’ve ever seen. If we were to see a drought like 2012, the reservoirs would continue to decline.”

For the river basin states, the consequences of the river drying could be major. If Lake Mead drops to below critical water levels, Arizona, considered a lesser priority than other river basin states after passing the Groundwater Act of 1980, would completely lose access to Colorado River water.

While Colorado doesn’t face that danger, Colorado and the other states using the river would face a big economic hit. According to a study from Arizona State University, losing access to the river, a main source of municipal and industrial water in the Southwest, would cost the region $1.4 trillion.

While the region would take a huge economic hit, Kowalski said the environmental cost would be worse, and work in the region should be about preventing these problems rather than combating them head on.

“The environment would be the biggest loser,” Kowalski said. “We want to hold hydrology not in the throes, but in advance of this crisis.”

Trends in supply and water use in the Colorado River Basin