The Fourth of July heat wave that occurred on the East Coast triggered record-breaking temperatures in the Potomac River, specifically on the north side of Little Falls, Maryland, and it caused a huge fish kill, according to officials.

It is stated by the Maryland Department of the Environment that one of the entity’s biologists registered a 94-degree water temperature July 4, with United States Geological Survey (USGS) data showing that water temperatures had hit a peak of 98.4 degrees.

The temperature is the warmest ever registered since record-keeping started in 1988 at this location, according to the FOX Forecast Center. (RELATED: Super Typhoon Bavi Becomes ‘Gargantuan’ As It Rolls Toward China, Taiwan)

Officials stated that the fish kill stretched approximately 14 miles in Montgomery County between Violette’s Lock and White’s Ferry.

The majority of the fish discovered dead were identified as golden redhorse suckers. According to scientists, the water temperatures caused stress for the fish and are a main reason why there were so many deaths.

Fish kill triggered in Potomac River as water temperatures surge to record 94 degrees due to extreme heat wave https://t.co/D1w7tzn0NF pic.twitter.com/65C7CuY8xD

— New York Post (@nypost) July 9, 2026

Less dissolved oxygen is held in water that’s warmer, which leaves less available oxygen for fish.

It is stated by the department that there isn’t any evidence of pollution or a chemical spill that contributed to the kill.

The kill happened after three consecutive days of record-breaking temperatures in Washington, D.C., which included a 103-degree register on Independence Day to set a new record. Speaking with FOX Weather, health officials in New Jersey say that at least 29 deaths that have occurred in multiple counties are being preliminarily connected to the historic heat wave.