 -- California Gov. Edmund G. Brown Jr. announced a set of mandatory water conservation measures today, as the state continues to struggle with a prolonged drought that has lasted for more than four years.

"Today we are standing on dry grass where there should be five feet of snow," Brown said in a statement after visiting a manual snow survey in the Sierra Nevadas. "This historic drought demands unprecedented action."

For the first time in the state's history, the governor has directed the State Water Resources Control Board to implement mandatory water reductions across California, in an effort to reduce water usage by 25 percent. The measures include replacing 50 million square feet of lawns throughout the state with drought-tolerant landscaping, banning the watering of grass on public street medians, requiring agricultural water users to report their water use to state regulators, and requiring large landscapes such as campuses, golf courses and cemeteries to make significant cuts in water use.

The governor’s announcement comes just a few weeks after NASA’s top water scientist, Jay Famiglietti, declared in a Los Angeles Times op-ed that California only had a year's-worth of water supply left in its reservoirs.

The last four years have been the driest in California’s recorded history. As of March 24, more than 98 percent of California is suffering from abnormally dry conditions, with 41.1 percent in an exceptional drought, according the U.S. Drought Monitor, which estimates that more than 37 million Californians have been affected by the drought. The state’s snowpack, which is largely responsible for feeding the state’s reservoirs, has been reduced to 8 percent of its historical average, and in some areas in the Central Valley the land is sinking a foot a year because of over-pumping of groundwater for agriculture.

In January 2014, Brown declared a state of emergency and directed state officials to take all necessary actions to prepare for water shortages. The announcement was quickly followed with the launch of a website, www.SaveOurWater.com, aimed to help Californians make reductions in water use. Tips include everything from reducing shower time to planting drought-resistant trees and plants.

“We are in an unprecedented, very serious situation,” the governor said in his January statement. “At some point, we have to learn to live with nature, we have to get on nature’s side and not abuse the resources that we have.”

Californians use an average of 181 gallons of water each day, according to the U.S. Geological Survey.

The winter wet season was a big disappointment for water conservationists. Half of the state’s annual rainfall usually arrives in December, January and February, and although there were brief stormy periods, California recorded less rain in January than any January before it: less than two inches. In March, the state announced emergency legislation to fast-track more than $1 billion in funding for drought relief and water infrastructure projects, after the State Water Board released a report outlining a steep decline in water conservation during the month of January.

California is not the only state struggling with drought. In Nevada, the Lake Tahoe Basin’s snowpack is reported to be at 3 percent of its normal average, prompting the primary water provider in the Reno-Sparks area to urge customers to cut water use by 10 percent on Tuesday. In Texas, more than half the state is currently suffering under abnormally dry conditions, according to the U.S. Drought Monitor.