Under pressure from the state and an environmental group, Newark, New Jersey officials in the US have increased the flow of water from the Oak Ridge water supply reservoir to head off a possible fish kill in the Pequannock river. River temperatures had reached 25oC in some places, just 3°C below conditions considered uninhabitable for some fish.

Newark officials said recent heavy rains had filled Oak Ridge beyond its normal capacity of 11.4B litres, causing warm surface water to flow over the reservoir’s spillway into the Pequannock river. The Pequannock is usually fed by cool water released from the bottom of the reservoir through valves controlled by Newark’s water supply division. The temperature of the bottom water is typically around 10oC.