Dissolved oxygen levels have dropped so significantly in the New River that some fish have been killed. The occurrence has been regularly observed after hurricanes and heavy rain events when low oxygen water from swamps is washed into rivers.
“This is a normal process after a hurricane or a major flood,” said Pat Donovan-Brandenburg, Stormwater Manager for the City of Jacksonville. “Flood waters brought with them an enormous amount of anaerobic swamp waters that robbed the river of oxygen.”
City of Jacksonville Water Quality technicians have found low dissolved oxygen levels in the New River after an investigation was launched when several dead fish were found floating in the river. About two dozen fish were found dead in an upper portion of the river, and more fish were found south of that site.
“Over a period of time, this should clear up,” said Donovan-Brandenburg. “Even hot and sunny weather contributes to these lower levels.”
Several wastewater spills have been reported in the New River as a result of Florence. The City of Jacksonville estimates that about 10 million gallons of untreated wastewater spilled from various points in the City of Jacksonville’s wastewater system during the heavy rain and wind events of Hurricane Florence.
However, as in the case of some other spills, the Jacksonville spills were not concentrated in one location, and occurred over a period of extraordinary heavy rains. That amount of rain significantly diluted the wastewater and lessened its impact. When the main pumping station was operating during the storm, between 11 to 12 million gallons a day was being pumped. On a normal day the City pumps around 5 million gallons of wastewater. Much of what was being pumped, was rainwater that got into the system.
The fish kill came well after the river had crested and many days after the wastewater spills.
The Jacksonville Main Pumping Station lost power during the height of the storm late Saturday, September 15 and the backup generator was malfunctioning. No wastewater pumping took place between late afternoon on Saturday, September 15 to around noon on Sunday, September 16.
The wastewater leaked out of various manholes and pump stations during this period when the Main Pump Station was not working properly. At the same time, the City was still receiving a record 35 inches of rain.
State environmental officials were aware of the issue and the City was in regular contact with environmental officials before, during and now after the storm about City operations. The officials have also been made aware of the levels in the lagoons which help to treat wastewater at the Land Treatment Site. There were no threats of spillage from the City’s lagoons at any time during the storm.
City officials are urging caution around the river as other hazards may exist such as debris. The City’s Water Quality staff is continuing to monitor the river as it does regularly.