The release of water down the Salt River has closed the McKellips Road crossing, near Loop 202, in northwest Mesa.
Salt River Project, the Valley's water/power utility, has been sending the water down the normally dry river because the system of reservoirs is too full to store runoff from recent winter storms.
As of Thursday morning, the four lakes on the Salt River were 99 percent full. The Verde River's two lakes, with far less capacity, were at 57 percent.
SRP began releasing water from its Granite Reef Diversion Dam on Friday.
It took time for the water to reach McKellips because the riverbed, between the dam and the road, has gravel pits that fill first.
Currently, the flow over the dam is 1,100 cubic feet per second.
SRP also sent water down a pair of canals into the Valley.
The Gilbert Road crossing in the Salt River's bed has been closed for more than a year. Last winter's storms necessitated the release of water, which damaged the pavement. The two-lane bridge at Gilbert, which normally handles southbound traffic, now carries vehicles in both directions.
Operations at Tempe Town Lake have not been disrupted by the release of water.
If flows were to exceed 10,000 cubic feet per second, the city would expect some debris to pass although the lake level would be expected to remain constant.
At 30,000 cubic feet per second, the dams would be partially lowered and then adjusted to any increased flow thereafter.