The Po River is Italy's largest reservoir of freshwater and much of it is used by farmers.

Italy's rich northern Lombardy region prepared to declare a state of emergency Thursday over a record drought which is threatening crops and has forced towns in the Po Valley to ration water.

"It's an extremely delicate situation," regional chief Attilio Fontana told reporters as the valley, which stretches across the north and houses a crucial agricultural sector, suffered its worst drought in 70 years.

Fontana said a state of emergency was likely to be declared for Lombardy, home to Milan, as well as three other neighboring regions: Piedmont, the Veneto and Emilia Romagna.

The Po River is Italy's largest reservoir of freshwater and much of it is used by farmers. Some areas have been without rain for over 110 days, according to the Po River observatory.

With no rain forecast, councils have begun installing water tankers and imposing hosepipe pans.

Utilitalia, a federation of water companies, has asked mayors in 100 towns in Piedmont and 25 in Lombardy to suspend nighttime drinking water supplies to replenish reservoir levels.

The drought is putting over 30 percent of national agricultural production and half of livestock farming in the valley at risk, Italy's largest agricultural association, Coldiretti, said Thursday.

The low level of the Po is also leading to salt seawater infiltration into low-lying agricultural areas, compounding farmers' problems, it said.