Home Archived January 13, 2017
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By Frank Scott
Quality of agricultural water is said to be decreasing here
For years, water experts have warned about the depletion of the Alluvial Aquifer in eastern Arkansas because of over-pumping for agricultural use. The southern part of Arkansas County has generally escaped the worst of the damage, due to recharge from the Arkansas and Mississippi rivers and Bayou Meto.

But data being compiled by the United States Geological Society (USGS) shows that while the quantity of water is still high, the quality is deteriorating.

A test of water from the Alluvial Aquifer shows that the level of chlorides (naturally occurring salts) has increased since the USGS last did the test three years ago.

"The water levels in the Alluvial Aquifer are dropping one to three feet a year," said Ralf Montanus, a USGS field agent who has been conducting water level and quality tests of select wells in Arkansas County and around the state this year." Because of this drop, the remaining water contains more chlorides."

Some chlorides can be beneficial for crops, but a too-high level can have detrimental effects.

"High levels of chlorides can be bad for crops because they tend to have a burning effect," said Arkansas County Extension Service agriculture agent Ken Adams. "However, they would have to be pretty high to have an effect."

Adams said that high levels of chlorides have never been a problem in southern Arkansas County. In fact, the Extension Service's normal soil-testing procedure does not include a test for chloride levels.

"We don't have a problem with chlorides right now," Adams said.

However, Adams said that if chloride levels in the Alluvial Aquifer are indeed rising, they could eventually cause problems for local farmers.

"In Chicot County, the level of salt (sodium chloride) got so high, they had to quit raising rice," Adams said. "Rice is really sensitive to salt. If the salt level [in the water used to flood the fields] is very high, the rice gets to about two inches [high], then dies."

If the level of chlorides in the Alluvial Aquifer do continue to rise, Adams said, area farmers may have no choice but to change to other crops.

"I don't know of any treatment" for high chloride levels, Adams said.

While the USGS data on chloride levels in the Alluvial Aquifer will not be available until 2008, they are likely to show increased chloride levels.

Data from the 27 USGS test wells in Arkansas County show that the water level in those wells has decreased an average of about two inches per year since 1982. Some wells, such as one in Almyra, one north of St. Charles and one west of DeWitt have remained stable over that period. The water level in one test well southwest of DeWitt has increased over that period.

However, other test wells show a more precipitous decline. According to USGS data, the water level in a test well northeast of DeWitt has decreased more than 15 feet in the last decade. Another test well in Tichnor has declined about the same amount, and a well east of DeWitt has declined 10 feet in the last five years, after being stable for most of the last 40 years.

The decrease in water levels is "getting worse in some areas of Arkansas County," Montanus said. "And if the water levels continue to decrease, the chloride levels will get higher, and that could be bad for farmers."
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