Durham, N.C. — The Bull City tightened water restrictions Monday.

City officials agreed last week to move to Stage 4 severe mandatory conservation measures, which calls on businesses to reduce their usage by 50 percent. Managers must document their efforts to reach that goal.

The city's water-supply notice on its Web site said Monday that the system has 59 days of easily accessible water in its two primary sources and 57 days of water that is harder to pump because it is below intake pipes.

In about two weeks, the city plans to install a tap at Teer Quarry, which officialssaid holds about 25 days of water.