After four years of a crushing drought, Californians are hoping El Niño storms bring relief this winter.

But whether they replenish the state’s reservoirs and rebuild its crucial snowpack remains to be seen, with many experts cautioning that the state’s water deficit is too severe to be resolved in one rainy year.

So 2016 promises to be another critical year in California water policy centering on politically charged discussions of whether Gov. Jerry Brown (D) will extend urban conservation mandates and succeed in dramatically reshaping Northern California’s water infrastructure with the construction of two 30-mile-long tunnels under the Sacramento-San Joaquin Bay Delta.

The Scripps Institution of Oceanography in La Jolla, California has long been a leader in studying the weather phenomenon known as El Niño. In a recent Scripps video a handful of scientists recount the story of El Niño forecasting by remembering that the strong El Niño of 1982-83was a complete surprise, catching unaware not just the scientists but also the state’s emergency services. Never again, they said, and when they saw a strong El Niño taking shape in 1997-98, they sounded the alarm early.

The current El Niño is already the strongest since 1950 in many areas of California, including the fertile San Joaquin Valley, where many of the country’s fruits and vegetables are grown. Fresno has seen 6.61 inches of rain since October 1; the historical average is 4.64 inches, according to the Fresno Bee.

There is more rain on the way: the National Weather Service forecasts two new storm systems will move into the area on Monday and Tuesday, dropping rain in the Valley and snow in the Sierra Nevada.

Farmers in California’s fertile San Joaquin Valley are bracing to receive no irrigation water from the federal government for a third consecutive year.

They’re hoping for El Nino-driven storms to produce the very wet winter they need. Reservoirs and groundwater supplies are critically low after four drought years.