Arizona has determined that there is not enough groundwater for all of the future housing construction that has already been approved in the Phoenix area, and will stop developers from building some new subdivisions, a sign of looming trouble in the West and other places where overuse, drought and climate change are straining water supplies.

The decision by state officials marks the beginning of the end to the explosive development that has made the Phoenix metropolitan region the fastest growing in the country.

Arizona, California and Nevada have agreed to take less water from the drought-strained Colorado River, a breakthrough agreement that, for now, keeps the river from falling so low that it would jeopardize water supplies for major Western cities like Phoenix and Los Angeles as well as for some of America’s most productive farmland.

Seven U.S. states that depend on the overused Colorado River on Monday reached agreement to cut consumption from a river that provides drinking water for 40 million people and irrigation for some of the country's most bountiful farmland.

In the agreement with the Biden administration, announced by the U.S. Department of the Interior, Arizona, California and Nevada will take 3 million acre-feet (3.7 billion cubic meters) less from the river through the end of 2026, an amount equal to 13% their allotment.

The Biden administration reached consensus Monday on a historic Colorado River Basin conservation deal after securing agreement from California, Arizona, and Nevada.

The agreement with the three states, which together make up the river's Lower Basin, is slated to last through the end of 2026, the Interior Department said in a statement on Monday. It will also conserve at least 3 million acre-feet of water.

Drought in a southern Central Texas county is so severe that cows are grazing in the middle of a dried-up lake.

Much of the western United States has recently assuaged its drought after an excessively wet winter on the west coast alleviated nearly all of California's drought struggles. The weather impacted states further inland as well, supplementing reservoirs in Utah and all but eliminating drought in the west.

As pollution, engineering, population growth and climate change pose challenges to freshwater quality and quantity in America, the safety and amount of water in parts of the U.S. is in question.

Environmental experts told ABC News about the future of water in America and problems the country is facing now.

Where is America's water crisis?

Even a winter packed with rain and snow could not bring the Colorado River crisis to an end. The river is still drying out. And on Tuesday, government officials announced two historic proposals to prevent the system and the some 40 million people it sustains from crashing.

The Biden administration proposed actions Tuesday that would significantly reduce water supplies in seven western states amid severe drought conditions that stretch back decades.

The Department of the Interior (DOI) released a draft proposal that highlighted two potential actions it could take to combat the Colorado River Basin's deteriorating water levels. The two proposals would each consist of federally-mandated supply reductions for states that are dependent on the river system which provides water for more than 40 million Americans and is vital for western states' economies.

The Colorado River is in a dire state. The river, which provides water for 40 million people, is drying up rapidly due to the ongoing megadrought in the southwest. Over the last century, the river's flow has dropped by 20 percent, according to data from the U.S. Geological Survey.

Experts have long feared what it will mean for life in the Southwest as we know it, if the situation were to worsen.

But now, we have a glimpse into what life could be like if the crisis worsens to the point where drastic measures need to be taken.

The United Nations water conference starts tomorrow. Co-hosted by the Netherlands and Tajikistan, the three-day event will take place at UN headquarters in New York and will be the first such event in nearly half a century. During that time, a rising number of people around the world have gained access to safe water and sanitation (see ‘A tale of two halves’) — except in sub-Saharan Africa (see ‘The neglect of Africa’), where the numbers without safe drinking-water services are greater than they were in 2000.