“Early Thursday morning,” Murfreesboro Environmental Engineer Sam Huddleston said, City staff was notified of a fish kill at the Gateway Island Reception Center pond.

“City personnel from the departments of Parks and Recreation (MPRD), Murfreesboro Water and Sewer (MWSD) and Engineering were sent to investigate,” he continued. “When we arrived, an estimated 2,000 pounds of dead fish were discovered on the lower or western pond.”

Since then, some living fish have been discovered in the lower pond and no dead fish were found in the upper pond, he said.

“As with most fish kills in closed pond systems,” he said, “we suspected the culprit was an overnight transient water quality episode involving dissolved oxygen.

“Other contributing factors considered included temperature, chlorine content, and possible failure of pond water circulation equipment,” he continued. “City staff and contractors checked and reset these systems on Thursday.”

To speed up the process, dead fish were removed by a local environmental response company and city staff and will be disposed of in accordance with local and state requirements for waste management, Huddleston said. A visual check of West Fork Stones River between General Bragg Trailhead and Northwest Broad Street did not indicate any adverse impacts along this reach of the river. 

As a courtesy, City staff also notified Tennessee Division of Water Pollution Control and Division of Solid Waste Management, he explained. Since Gateway pond is a private pond similar to a farm pond or landscape pond, it is not subject to state requirements.

“City staff will monitor the conditions of the Gateway pond over the next several days to determine if this event resulted from an issue with the water quality of the pond,” the engineer said. “MWSD performed field tests of the pond’s water quality, including chlorine residual, dissolved oxygen, pH, temperature and conductivity and found levels in all were well within acceptable limits.

Other parameters were within normal ranges for the pond’s water quality, he said.

“At the current pond temperature of approximately 80 degrees Fahrenheit,”  he said, “pond water would be expected to contain less than 10 p.p.m. of dissolved oxygen. Surface water quality criteria levels for dissolved oxygen indicate that a minimum level of 5 p.p.m. is necessary for healthy waters for game fish such as bass.

The Gateway Island pond, featuring a 1.5-acre upper pond and six acre lower pond, was initially constructed as one of the first storm water management projects on property the city owned along the north side of Medical Center Parkway.  It was enhanced to serve as a landscaped water feature for the island.

Water level is maintained by storm water runoff and is supplemented by MWSD reuse water. Water quality is managed by a system of recirculation pumps, fountains, water falls, simulated stream features and a sonic algae control device and no chemical treatment is utilized.

Re-use water added to the pond does contain a state-required level of chlorine as it is discharged into the pond, Huddleston said. During the summer, more reuse water is added to maintain a constant water level.

This reuse water is provided in select city locations for irrigation and landscape maintenance as well as makeup water to the Old Fort Golf Course and Gateway Island Reception Center Pond to maintain constant water levels.