Search crews sifting through flood debris from the Memorial Day weekend rains in Texas discovered a man's dead body, they said. The discovery brings the death toll from the May storms to at least 23, CNN reported.

The unidentified man was found Saturday in debris near the Blanco River in San Marcos, Texas, city officials said. Authorities said they had not determined if it's the body of a 42-year-old man who remained among those listed as missing in the flooding.

The body was discovered as federal authorities expanded the disaster declaration for Texas counties affected by torrential rains. The Federal Emergency Management Agency named 20 additional counties to the updated declaration. Homeland Security Secretary Jeh Johnson was expected in the Houston area to tour a school damaged by the flood.

The original May 29 federal assistance request listed only three counties. The declaration makes relief funds available to victims.

The storms caused at least $27 million in infrastructure damage, according to Texas transportation officials. Roadways in 167 of the state's 254 counties suffered storm damage in May, which National Weather Service forecasters estimated as a 150- to 200-year flood event.

Torrential rains caused widespread flooding, inundating businesses and homes with water. The weather event dumped more than 37 trillion gallons of water on the state. That's enough water to cover every part of Texas with ankle-deep water, meteorologists told CNN. The storms also caused destruction and deaths in Oklahoma and Mexico, several media outlets have reported.

Farmers in Texas say they are bracing for the worst during the upcoming harvest season. Crop losses because of the floods are estimated to reach "many millions of dollars," said Gene Hall, spokesperson for the Texas Farm Bureau, according to CNN. Hay farmers may not be able to get into their damaged fields to harvest, and cotton farmers may not be able to plant, Hall said.