pascagoula — The Mississippi Department of Environmental Quality (DEQ) has scheduled a public hearing at 7:30 p.m. May 28 at the LaFont Inn to take comments on a proposed new low-flow standard for the Pascagoula River.
Currently, a statistical model called 7Q10 is used to determine how low water in state streams can get before no more water withdrawals are allowed in order to protect aquatic life. Charles Branch, head of the DEQ’s Office of Land and Water Resources, said a new standard is being proposed for the Pascagoula River that takes into account water quality and the biological conditions of the river.
“7Q10 is strictly a statistical analysis,” Branch said. “A shortcoming of using any statistic basis is it doesn’t take into account biological factors.”
The 7Q10 standard, which has been in effect in the state since 1956, was questionable being applied to a river like the Pascagoula whose water levels are affected by the tide and winds as well as rainfall, Branch said.
“The final conclusion after talking with various public and private sector experts was the 7Q10 standards couldn’t be applied to the Pascagoula River at Combust Bluff because this wasn’t a steady-state, balanced hydrological regime,” Branch said.
Water is withdrawn at Combust Bluff and transported by pipeline for use by Jackson County industries. Chevron Pascagoula Refinery uses large amounts of water from the Pascagoula River for its operations.
Steve Renfroe, public affairs manager for Chevron in Mississippi, said the refinery can’t operate without the surface water. Several times in the past 30 years the level of the Pascagoula River has fallen to the point where it nearly reached the level where water withdrawals would have been stopped.
Renfroe said that while the refinery never had to shut down because of the water supply, it came close several times. The new low flow limit would allow more water withdrawal than under the current standard.
“The 7Q10 level was based on a general standard, and was not site specific,” Renfroe said. “We felt like it would make more sense for low flow to be a site-specific standard which meant some scientific research would have to be done. That was done, and used to developed the new standard. We support this scientific approach to establishing low flow.”
Chevron Pascagoula Refinery processes 295,000 barrels of crude oil per day, producing about 5.5 million gallons of gasoline per day.