Cici Williams Steward told a panel of Texas legislators on Wednesday of the moment she shared the news with her 5-year-old daughter just days before kindergarten was to start: her big sister, 8-year-old Cile, was not coming back from Camp Mystic.

“She needed to hear the unbearable truth from us, not from kids on the playground,” said Ms. Steward, the mother of the last camper still missing from a children’s sleep-away retreat devastated by the July 4 floods in Texas Hill Country.

“We are forced to pray for the day when our child’s body is found, and to call that good news,” she told committee members considering a new state law to strengthen safety protocols in camp sites and other flood prone areas. “My baby girl is still missing.”

Ms. Steward’s testimony marked the first time parents of the campers testified in a public forum since the floods that ravaged the Texas Hill Country, known for its summer camps, vacation homes, campsites and RV parks. And they offered lawmakers an emotional assessment of the region’s preparations for such a catastrophic flood.

“Training should prepare staff and campers to act, not to wait,” said Matthew Childress, whose camp-counselor daughter, Chloe, 18, died trying to protect young girls under her care. “There needs to be better coordination with local first responders, because in an emergency, confusion kills, and we saw that on July 4.”

Nearly all of Camp Mystic’s victims were confined to two cabins near the Guadalupe River, and many of the more than a dozen parents of the victims recounted the moments they had to enter a morgue to identify their children’s bodies. They pleaded with members of a State Senate committee to approve legislation that would improve flood warning systems, bolster internet communication, improve training and supply rescue equipment such as ladders.

Kerr County, at the heart of the region, suffered the brunt of the casualties, with 116 known deaths, including at least 28 counselors and campers from Camp Mystic. Most of the casualties came from a cabin known as Bubble Inn, where no one survived, and another one known as Twins. Dick Eastland, the camp’s longtime director, died trying to rescue children from those cabins, reserved for the youngest campers.

Kerr County officials and camp coordinators have faced questions about their lack of action amid increasingly worrying weather alerts in the early hours of the Fourth of July, as well as the county’s failure to secure funding for a flood warning system.

Meantime, Texas leaders have avoided blaming one another for oversights and inaction that may have contributed to the flooding’s death toll and infrastructure collapse. Gov. Greg Abbott has said that those looking for people to blame were “losers.”

Leading up to the hearing, some families of the victims had been meeting with state elected officials behind closed doors to lobby for the changes.

The legislators said that they expect the legislation to pass.

The hearing at the State Capitol in Austin came days after Mr. Abbott called for a second special session to address the flooding, and to consider new congressional maps to benefit Republicans in next year’s midterm elections.

Many of the parents had strong words for those responsible for security measures at Camp Mystic. Michael McCown, whose daughter Linnie was 8 when she died during the floods, told the state lawmakers that miscommunication only made his uncertainty more wrenching in the hours after the flood.

Mr. McCown recalled receiving an email from the camp telling him that if he had not been personally contacted, his daughter was “accounted for.” Days later, he provided a DNA sample and was given the news that he had been dreading.

“We trusted Camp Mystic with her precious life, but that trust was broken in the most devastating way,” he testified.

A day after the floods, he said, he stared at the wreckage of the camp, where he hoped his daughter got to live some of her happiest moments.

“How could these girls vanish into the night without anyone having eyes on them?” he said.

State Senator Lois Kolkhorst, a Republican from Brenham, Texas, tried to reassure the parents as her voice broke.

“I want you to know you’re being heard; you are impacting lives,” Ms. Kolkhorst said, “because of the lives of these precious children, we will never unhear their stories.”

Mr. Childress told legislators that the people who ran the camp were not prepared. Many of the cabins lay within the river’s flood zones, including the structures where the youngest campers slept. Teenage counselors were left to communicate with flashlights and screams as the waters swept through the camp. Camp Mystic was not accredited by the American Camp Association, a national body that maintains standards on camp safety and emergency preparedness, a break from other summer camps along that stretch of the river.

Some of the mothers who spoke also recounted how Camp Mystic became a rite of passage for the female members of their family. Ms. Steward said Cile was the third generation of her family to attend the camp.

“This year it was finally Cile’s turn,” she said. “She was 8 years old, going for the very first time, her heart full of excitement, to join the tradition.”

Other parents took the opportunity to share with the world a glimpse of their daughters’ short but artistic lives. Lars Hollis played a musical piece his 8-year-old daughter, Virginia, composed before she died.

“I’d like to leave you by sharing a treasure Virginia left for us,” Mr. Hollis said.

And for a few minutes, he lifted his phone up and held the room’s attention with the sounds of a little girl’s piano melody.