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Water quality questions raised

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Posted: Monday, April 8, 2013 7:22 am

HARLINGEN — As the prolonged drought tightens its grip on the Rio Grande Valley, reservoir levels continue to drop and city water treatment plants will be processing poorer quality raw water from the Rio Grande, say regional, state and local water officials.

News that Mexico is releasing part of the water it owes under a 1944 treaty is good, but lower levels in Falcon and Amistad lakes and the Rio Grande will still result in lower quality water received for treatment, officials said.

Use of chemicals will have to increase as raw water quality drops, but drinking water is monitored daily and quality at the tap will not suffer, city officials said.

David R. Sanchez, water services director for Harlingen WaterWorks System, said Friday that incoming water must be monitored daily and treatment adjusted to deal with increasingly dirty water in the Rio Grande.

Harlingen’s raw water comes directly from the Rio Grande through a canal owned by Harlingen Irrigation District to the city’s two reservoirs, the downtown City Lake and Dixieland Lake, Sanchez said.

“Anytime you have a lake, you have different strata of water and every strata is a different quality,” he said. “With surface water, you have to monitor constantly and the treatment changes with the water quality. … If the city does a good job, you should not be impacted one iota.”

But the quality of the water from the river that divides the United States from Mexico has dropped dramatically over the past 20 years, he said.

“Nuevo Laredo (Mexico) is still the biggest issue,” Sanchez said of that city’s poor record of treating sewage before releasing it into the Rio Grande.

But Harlingen’s water supply has never reached the level of having to issue a “boil water notice” because of measurable levels of fecal coliform, which would indicate possible pollution from human waste, Sanchez.

“I’m proud to say that Harlingen has never had to issue a ‘boil water order,’” Sanchez said.

Sometimes, Harlingen’s drinking water can have a smell like fish, Sanchez said.

“In the summer, when there’s an algae bloom,” he said. “If the (treatment) plant is geared up properly, you should be able to deal with an algae bloom.”

Sometimes the city is criticized when workers are seen releasing large amounts of water from fire hydrants during a drought, Sanchez said. But the releases are necessary if water has remained in the city’s system of water lines too long, he said.

“Water only has a certain ‘shelf life,’” he said. “From the day it leaves the water plant, water begins to degrade. You only have a certain window to use that water.”

Anytime tests don’t yield acceptable results, water lines are flushed until tests give acceptable readings, he said. The water is being released to maintain quality, even if there is a drought.

The Texas Commission on Environmental Quality said the water purification process Harlingen uses, a combination of chemicals called chloramines, is used statewide to disinfect drinking water.

“To produce drinking water quality that does not exceed the allowable concentration level for disinfection byproducts, all surface water treatment plants in Texas use chloramines — a blend of chlorine and ammonia — as a disinfectant within the distribution system,” TCEQ spokeswoman Andrea Morrow said in a Friday statement.

“The dead fish odor and bad taste can occur when the chemical bond between chlorine and ammonia breaks down over time within the distribution,” Morrow said. “In addition this can also occur if a public water system is treating well water with only chlorine and surface water with chloramines and then blending the two within the distribution system.”

But Sanchez said Harlingen’s public water system does not use well water.

Unlike city water systems in Raymondville and Lyford, which draw water through a long canal system from the Rio Grande to Delta Lake in Hidalgo County and then on to Raymondville, Harlingen’s raw water comes directly from the Rio Grande through a much shorter canal, local officials said.

Increasing the use of chemicals is necessary when there are lower water levels in the Rio Grande and in canals, TCEQ said.

“It is normal for chemical and microbiological concentrations to increase when there are lower reservoir water levels and reduced flows in rivers due to the evaporation of water,” TCEQ’s Morrow said.

“Increased concentrations of chemical and microbiological contaminants in surface water do normally require an increase in chemical feed rates and/or a change in the chemical(s) being used.”

Raymondville has instituted strict water restrictions due to the drought. City Manager Eleazar “Yogi” Garcia said there will be not problem providing pure water.

It may become very expensive to get water to treat due to his city’s location at the end of two long canals, he said.

As in Harlingen and elsewhere, Raymondville city water plant workers constantly monitor the quality of raw water being treated, Garcia said.

If more chemicals must be injected into the system to ensure purity, it will be done, but he doesn’t expect quality of water from the Rio Grande to drop severely, he said.

La Feria City Manager Sunny Philip said that, although La Feria gets its water from the same Delta Lake Irrigation District canal as Raymondville and Lyford, La Feria is much closer to the Rio Grande. His city is much less likely to have to purchase extra water in order to get its municipal deliveries.

But keeping drinking water at a high standard will be just as much a concern for La Feria as other Valley cities, he said.

“As the drought continues, the (river) water will be murkier and take more chemicals to process it,” he said.

His city owns about twice as many water rights as its annual needs, Philip said.

If “push water” is needed to bring in water through the canal system, La Feria already owns enough water to take care of that need in addition to the water actually used by the city, he said. But the water received at the city water plant could become harder and harder to purify, he said.


Allen Essex writes for the Valley Morning Star in Harlingen. He can be reached at aessex@valleystar.com.

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