What’s Killing the Fish Near San Estevan?

A fish kill has been reported near San Estevan Village in the Orange Walk District. Chief Environmental Officer Anthony Mai confirmed that the Department of Environment (DOE) responded after receiving reports of dead fish along a section of the New River.

“We conducted water quality monitoring in the area where the fish kill was observed,” Mai said. “The data highlights what we believe is the cause of the fish kill. This is an occurrence that happens almost every year or every two years.”

According to Mai, preliminary findings point to extremely low dissolved oxygen levels in the river, a condition that can suffocate aquatic life. Testing conducted from the Toll Bridge to the San Estevan area showed depleted oxygen levels in multiple sections of the river.

The DOE also recorded elevated chlorophyll-a levels at various depths, indicating the presence of an algae bloom. Algae blooms are typically triggered by high concentrations of nutrients such as nitrates and phosphates in the water. “When algae proliferate, they draw down the oxygen levels in the water, creating what we call an anoxic state. That leads to fish kill,” Mai explained.

The New River has experienced similar ecological stress in the past, most notably in 2019 when severe eutrophication, excessive nutrient buildup, led to significant degradation of water quality.

Mai noted that the river’s natural characteristics contribute to its vulnerability. The New River is relatively flat and slow-moving, and tidal influences from the coast can push saltwater upstream, further affecting its delicate ecosystem.