A dolphin who found itself stuck in shallow water in Melbourne's west has been towed to safety with help from Melbourne Zoo and Victoria Police.

The dolphin was found beached in shallow water in the section of Port Phillip Bay alongside Greenwich Reserve in Williamstown yesterday afternoon.

Marine animal experts from Melbourne Zoo's Marine Response Unit were called to help the dolphin, before they called for backup from water police just after 4pm.

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The group of rescuers made a sling to tow the dolphin into deeper water.

It was then assessed by experts before being successfully released back into the ocean.

Victoria Police's Leading Senior Constable, Tony Christensen, said "it was a privilege to be involved in the rescue of such an amazing creature".

"Our members often see dolphins in the bay during patrols and it's great to see this one back where it belongs," he said.