Despite those tensions, several people on the reservation said they would have liked to see a more robust National Guard and state government presence during the storm response. As members of the tribe volunteered to cook meals and unload food delivery trucks on Friday, and as people checked on older neighbors who lived far from the highway, some of the biggest needs remained unmet.

“We just need the technical skills,” said Mary Tobacco, who was helping lead recovery efforts, but who became stranded herself on Friday as rising water made it impossible to leave her home on a butte. (The water was moving too fast, she said, to make it out in her kayak.)

Tribal officials were still working to determine whether as many as four more deaths in the past two weeks could be attributed to the storm, including some involving patients who needed medical help and could not be reached by ambulance. The tribe’s police chief, Robert Ecoffey, said on Friday that it was not known whether those people would have survived if an ambulance had reached them.

In the meantime, some on Pine Ridge were hunkering down for what could be weeks more with little or no access to the outside world.

Bernadine Rowland, stranded since March 12, said Saturday that she and her grandchildren had remained in good spirits and had passed the days by watching Netflix and YouTube videos. But her pantry had started to get bare — only two bags of beans left, plus some oatmeal and rice — and an attempted food delivery by horseback had to be aborted Friday afternoon because a creek that had to be crossed was running too high.

Just before sunset Friday night, the horseback riders came back, this time by canoe, carrying big plastic bags full of macaroni and cheese, toilet paper, Hamburger Helper and canned pasta.

“It was a relief,” Ms. Rowland said. “We’ll have something to last us for a while.”