Flooding that has hit parts of the Midwest hard has nearly paralyzed an American Indian reservation in southern South Dakota, swamping roads, trapping people in homes and cutting off water supplies to thousands.

The situation on the sprawling Pine Ridge Reservation was improving Tuesday, but two weeks of severe flooding could put the Oglala Sioux tribe in recovery mode for months, if not longer, and deal a serious blow to its economy, President Julian Bear Runner said.

“This is going to have a devastating effect on us, I feel,” he said. “The tribe is utilizing any and all of its resources to try to help the communities that have been impacted.”

The prairie reservation is roughly the size of Delaware and Rhode Island combined and is home to nearly 20,000 people, about half living in poverty, according to U.S. Census Bureau statistics. Heavy snowfall and a rapid melt this month led to overland flooding, swollen creeks and rivers, swamped roads and broken water lines.

“Pine Ridge is like a desert when it comes to resources,” said Peri Pourier, a tribal member and state representative. “We’re using horses to get out to communities that are away from the main roads. We have elders out there that are just isolated.”

Bear Runner, 33, said it’s the worst flooding he has seen and that some tribal elders say they haven’t seen so much water since they were children. He said the tribe was still on the “borderline” of emergency Tuesday with floodwaters receding, but many tribal members still don’t have easy access “to pharmacies, medication, grocery stores, anything to help sustain themselves.”

The tribe estimates as many as 8,000 people have had water supplies disrupted and another 2,000 have been hampered or trapped by floodwaters. Three people who suffered medical problems died before ambulances slowed by floodwaters could get to them, the tribe said, though it released no other details.