“On the second trip, the water was running over the road. It was probably ankle deep,” Edward Eastland said. By then, water covered the sloping grass between the cabins and the river. Lightning crashed, revealing canoes floating over the soccer field.

Soon it was up to the top of his truck tires, he said.

At that point, Mr. Eastland and his father turned to the cabins of the youngest campers, Bubble Inn and Twins. A video, taken at 3:26 a.m. by one of the workers from a second-floor sleeping area above the commissary, captured deepening water swiftly moving past Twins, while, in the distance, campers were still able to wade through ankle and knee-deep water into the rec hall.

Mr. Juenke ended up in a cabin called Wiggle Inn, where he would ride out the rising water, with the campers and two counselors floating on inflatable mattresses. “We’re going to be OK,” Mr. Juenke recalled telling them.

3:50 a.m.

Dick Eastland parked his S.U.V. by the entrance to Bubble Inn. “He was standing outside of his Tahoe, and the water was rushing all around these cabins at this point, it was probably two or three feet,” his son said. “That’s the last place I saw him.”

Edward Eastland walked around Giggle Box and through waist-high water to the pair of connected cabins known as Twins.

“It feels like rapids at that point,” he said. He saw two counselors calling out for help from the porch. As he got to the cabin, he said he thought to himself, “we cannot get these eight-year-olds out of this cabin in this water.”

Water, he said, had never reached the cabin, not in 100 years. “It was unbelievable,” Edward Eastland recalled.

Inside the first Twins cabin, a dozen 8-year-old girls huddled in the corner together on top of two bunk beds.

“I tell them, I’m here and I’m not leaving you guys, and everything’s gonna be OK,” he said. The 11 girls in the second Twins cabin were also on the top bunks. The water at that point was rushing by the doorways and filling both cabins.

“Water started coming in through the window,” he said. “I yelled to the counselors, does anybody have a screwdriver?” Edward Eastland was thinking of trying to remove a metal vent in the low ceiling to climb through. As he moved between cabins, the counselors were yelling that the water was chest high.

“I remember seeing the waterline and just praying that it would stop going up,” he said. “And it just kept going up.”

Mr. Eastland said he was able to talk to his father on the radio, and he heard him struggling in the water.

“He said, ‘I need help. I can’t move,’” Mr. Eastland recalled. “I said, I can’t.”

Dick Eastland appeared to have been trying to get the eight-year-old girls out of Bubble Inn and into his Tahoe. It was not clear if he loaded all 13 campers and two counselors inside.

“He was right there,” Mr. Eastland recalled, standing outside the Twins cabins on a recent sunny morning, with Bubble Inn just a few steps away. But from inside the cabin that night, Mr. Eastland said he could not see him.

Then his father’s radio seemed to malfunction, Mr. Eastland said.

The water picked up Dick Eastland’s S.U.V., carrying it forcefully over the soccer field, down past the archery range and into a grove by the river, smashing the vehicle against a tall Cypress.

A data report from his vehicle, reviewed by The Times, indicated a crash at 3:51 a.m. His Apple watch showed he went underwater at the same time. He was found dead in the S.U.V., along with three campers from Bubble Inn.

Around that time, Mr. Eastland said he was in the second Twins cabin, the water at his shoulders, when a counselor yelled from the other Twins cabin that the water was carrying girls out the door.

“I’m right here in the doorway, and three girls come out of that door,” Mr. Eastland recalled, his voice shaking. “I catch two of them, and one girl gets away into the darkness.”

As he held the two girls, and gripped the doorway, the water began to rise over his head. Another camper swept from the cabin behind him grabbed onto him.

“I have no idea who it was,” he said. “She put her arms around my neck” and tried to hold on.

Then, he said, the water pushed him and the girls holding onto him from the cabin into the surging river.

Data from his Apple watch, reviewed by The Times, indicated that Mr. Eastland went underwater at 4:09 a.m.

He struggled against the current. “I could feel the pressure, like I was almost to the top,” he said, but the surface, “it just, it wasn’t there.”

The flow of the water carried Mr. Eastland alone past a row of trees along the road where an hour before he had been evacuating campers. Now the water reached the branches, which he tried to seize. But, he said, they kept breaking.

Eventually the water pushed him into the canopy of a pair of large trees, just below the Bug House cabin. He grabbed on.

Several campers and counselors from the Twins cabins were already there, clinging for their lives, Mr. Eastland said. Eight campers and three counselors survived by holding on to the same trees, he said. Another counselor survived in a tree along the road, and another camper also was found alive nearby, he said. Three more campers were later found alive down river.

The scale of the loss became clear only after the water receded, Mr. Eastland said.

Eleven campers from the two Twins cabins died in the flood. All 13 campers and both counselors who were in Bubble Inn died. Another girl was swept away after trying to return to her cabin, Jumble House, for a blanket after evacuating.

The body of one girl from Twins, Cile Steward, 8, has still not been found.

The waterlines in the cabins, measured by The Times, rose well above the heads of the campers.

In one of the Twins cabins, the lines appeared to reach the low, flat ceiling. In the other, the water stopped a few inches from the ceiling.

None of the buildings at the camp, except for the gatehouse and a wing of the commissary used for storage, were destroyed, though many were damaged. In Bubble Inn, the waterline was 6 feet 3 inches from the floor.

The riverwaters eventually surrounded and filled the first floor of the open, two-story recreation hall, where 95 campers and 15 counselors had gathered for safety, according to figures provided by Camp Mystic. They huddled on the narrow second-floor balcony that wrapped around the log-frame structure, watching beneath them the water flow through the building.

The relatives of some of the 25 campers and two counselors who died have filed lawsuits against the camp and the Eastland family, arguing that the camp had been negligent in advance of the flood and that the last-minute rescue efforts were undertaken too late.

“The Camp chose not to evacuate its campers and counselors, even as floodwater reached the cabins, until counselors demanded it,” according to one of the suits. “When it was too late, the Camp made a hopeless ‘rescue’ effort from its self-created disaster.”

In interviews with The Times, Mr. Eastland and his brother Richard, who also works and lives at the camp, said that based on decades of experience living at the camp and running it through previous floods, they believed the cabins were the safest place for the campers.

“In our minds, the cabins were built on high ground,” Richard Eastland said.

The family felt that way even after a 2011 FEMA map placed most of the cabins, including Bubble Inn and Twins, within a 100-year flood zone. The camp hired surveyors who argued there were errors in the topography used for that map; the federal agency in 2013 removed the cabins from the floodplain maps.

But the July 4 flood had changed what high ground was for the camp, Richard Eastland said.

There had been no plan for how to evacuate campers, the Eastlands said. The evacuation was improvised, as the water level rose more rapidly than they had ever seen. The camp is planning to create an evacuation plan for the future, Richard Eastland said.

And, the Eastlands said, the camp will never again use the cabins that flooded to house campers or counselors.

“No, never,” Edward Eastland said.

But next summer they plan to reopen their separate, adjacent camp – Camp Mystic Cypress Lake – that sits higher up a hill and did not flood that holiday weekend.

Some families have welcomed the news, while others, including those whose children died in the flood and the lieutenant governor, Dan Patrick, have criticized the camp for its decision. The Texas Legislature is planning to hold hearings on what took place at the camp though a date has not yet been announced.

Edward Eastland said he has been going to counseling. He has returned many times to the spot where his father died along with several girls from Bubble Inn, at the base of a Cypress tree, by the now-gently flowing river.

“Every morning is horrible,” he said, his voice quavering. “I want to help the families. I don’t know what to do though.”

“We are so sorry,” said his wife, Mary Liz. “I feel like no one thinks that we’re sorry.”