A combination of record-high heat and record-low rainfall has pushed south and central Texas into the region's deepest drought in a half century, with $3.6 billion of crop and livestock losses piling up during the past nine months.

The heat wave has drastically reduced reservoirs and forced about 230 public water systems to declare mandatory water restrictions. Lower levels in lakes and rivers have been a blow to tourism, too, making summer boating, swimming and fishing activities impossible in some places.

"Summed up in one word: devastating," Texas Agriculture Commissioner Todd Staples said.

Nearly 80 of Texas' 254 counties are in "extreme" or "exceptional" drought, the worst possible levels on the U.S. Department of Agriculture's index.

In late April, the USDA designated 70 Texas counties as primary natural-disaster areas because of drought, above-normal temperatures and associated wildfires.

"If we don't get rain by early September, it could be trouble," said Mr. McAdams, a past president of the National Cattleman's Beef Association.

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