MOUNT VERNON, N.Y. (AP) — The death of a dolphin in a New York river that empties into Long Island sound has raised questions about water pollution.

Officials say the dolphin was found in the Hutchinson River in Mount Vernon Friday afternoon. The state Department of Environment Conservation was called to the scene. Experts say it is likely the marine mammal travelled upriver from the Long Island Sound.

The federal Environmental Protection Agency ordered Mount Vernon to stop raw sewage leaks from contaminating the river in 2003. However, repairs to the sewage system weren't approved by city council. The city could face fines.

Mayor Richard Thomas expressed his concern about the river's pollution in a statement.

Authorities say the DEC will perform a necropsy to determine the dolphin's cause of death.

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