Dissolved Oxygen

Dissolved Oxygen

How often does dissolved oxygen in the Great Bay and Hampton-Seabrook Estuaries fall below 5 mg/L?

Most of the time, dissolved oxygen levels remain well above 5 mg/L in the bays and open waters located at the center of the Great Bay and in Portsmouth Harbor. However, low dissolved oxygen events do occur in the Upper Piscataqua River, all the Great Bay Estuary tidal rivers, and the Hampton River in the Hampton-Seabrook Estuary. In 2021, most low dissolved oxygen events in the tidal rivers lasted between two and four hours. If these events remain sporadic and of short duration, negative impacts on aquatic organisms will likely be limited.


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