ROBSTOWN, Texas — The water district that serves Robstown and some rural residents in Nueces County exceeded state limits for arsenic and total dissolved solids, according to a Texas Commission on Environmental Quality letter dated Oct. 21.
Nueces County Water Control and Improvement District No. 3 Board President Ramiro Alejandro shared the letter on Facebook this week. He noted the test results were seven months old.
What the state found
TCEQ investigated the district's water system on March 10 following a complaint. The agency said it found no violations during that investigation but flagged two issues.
The first was total dissolved solids, or TDS, a measure of salt and minerals in water. Samples taken that day ranged from 1,370 to 1,680 milligrams per liter, above the state's 1,000 mg/L secondary standard. TCEQ said the district's new connection to Corpus Christi's water system could help improve water quality.
The second was arsenic. TCEQ said the district was over the limit of 10 parts per billion and that the problem is being handled in a state enforcement case.
How arsenic violations are measured
Arsenic compliance is not judged by a single test. TCEQ uses a running annual average. At the end of each quarter, the state averages the system's results from the past year. If that average is above 10 parts per billion, the system is over the limit.
The state samples cited in the letter, taken in August, December and January, came back at 11, 13 and 12 parts per billion. All three were above the limit, so the average was too.
Because the average covers a full year, one lower test result does not clear the problem right away. Results have to stay low long enough to pull the yearly average back under the limit.
What the district says
Alejandro wrote that the high TDS comes from groundwater wells Corpus Christi uses, which discharge into the Nueces River. He wrote that the district believes low lake levels may be behind the arsenic, "but we do not know for a fact."
He wrote that the Corpus Christi connection has been in use since May. When the city's wells are running and river TDS is high, the district gets up to 3 million gallons a day from Corpus Christi at no cost to the district, he wrote. He wrote the district's treated water "100% safe to consume."
How we got here
KRIS 6 News first reported the district's arsenic violation in February. Testing from October through December had found arsenic at 13.1 parts per billion. Customers of River Acres Water Supply, which gets its water from the district, were also notified.
In January, Corpus Christi City Council approved a deal to send the district up to 3 million gallons of treated water a day and pay about $1.7 million for the connection. In return, the city can lease up to 5 million gallons a day of the district's water. A Robstown resident objected to that trade.
In March, officials fast-tracked the line. Corpus Christi City Manager Peter Zanoni said the city's wells were not driving the arsenic but acknowledged they were contributing to the high TDS. District leaders later told the Robstown City Council that Corpus Christi is covering the cost of the connection.
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