Torrential rains this month washed away at least $1.3 million worth of South Carolina roads, and the bill is expected to rise as more damage surfaces, according to the state Department of Transportation.

“The problem is there is stuff out there that we are going to see over the next several months,” said Michael Black, director of the district maintenance office for the Charleston area.

Black said the situation is the worst in 10 years.

Sinkholes attributed to the rainfall opened up on Interstate 26 near Ridgeville and on Wire Road near Branchville. A sinkhole also occurred on Otranto Road, Black said.

Repairs are ongoing in Colleton County on Black Creek and Carter’s Ford roads. Carter’s Ford was hit with weather-related damage that took out one of the lanes, Black said. Part of Black Creek sank about a foot because of the rains, he added.

Combined, it will cost an estimated $126,000 to fix both Colleton roads, the DOT said.

Colleton sustained another $40,000 in rain-related road damage on secondary roads 24, 88 and 138, the DOT said.

A 60-square-foot hole at least 10 feet deep in the I-26 eastbound fast lane near Ridgeville caused major traffic snarls. It was repaired at a cost of $80,000.

The Wire Road sinkhole in Dorchester County was described as large enough to swallow a car. Crews repaired it at a cost of $10,000. In all, 11 secondary roads in Dorchester were closed because of rain damage, but most of them have reopened, Black said.

Matt Halter, Dorchester County public works director, said nine secondary roads were closed Thursday because of Edisto River flooding. The situation affects a handful of residents, he said, and the roads will re-open either Friday or Monday.

The rain that led to the river rising well beyond its banks is the worst since the late 1990s, he said.

“The river is starting to recede,” he said.

In the wake of the record rains, drainage-pipe failures, washed-out shoulders or pavement and bridges with structural damage were reported statewide. The DOT said 99 roads were damaged by heavy rain, including 48 with pipe failures and 39 with shoulders or pavement washed out. Twelve bridges either had water running over them or structural damage.

The I-26 sinkhole happened because of a leaking 10-foot-by-10-foot, box-shaped drainage culvert 18 feet below the road. The leak washed out soil beneath the culvert, causing it to settle and the sinkhole to form, officials said.

Statewide, most of the rain-damaged roads have been repaired, although more are expected to be identified.

The Upstate had the most costly road repairs attributed to the rains. The biggest tab was $250,000 to replace washed-out fill material on Interstate 385 in Laurens County, followed by $230,000 to fix U.S. 178 in Pickens County.

The National Weather Service reported at its website that rainfall recorded in the Charleston area is more than 15 inches above normal.