And North Wales Underwater Search and Marine Unit is now at the scene to probe the depths of the park's lakes.
The only official statement from police is as follows: "Police are currently present at Orrell Water Park in Wigan as part of an ongoing search for a missing person."
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However, only hours earlier an appeal was issued by officers to find 60-year-old Christine Foster.
And a local resident posted on social media that he had been helping with a search at the park.
Ms Foster had last been seen at 4.30pm on Wednesday November 17 in the Greenslate Road area of Orrell which is very close to the water park.
The 60-year-old is described as white, of slim build, 5ft tall and with blonde shoulder-length hair, blue eyes and dark coloured glasses.
David Waine wrote on Facebook: "Anyone heard of a missing lady called Christine in Orrell, around 60 years of age?
"I've just assisted the police for two like hours searching high and low through every nook and cranny round Orrell Res and all the surrounding areas - farmers' fields, all waters' edges, Winstanley College etc.
"Don't want to say too much as I don't know her, but I know she's unfortunately lost her dog recently, which meant the world to her, so obviously people are really worried for her safety.
"Police are looking everywhere. Pray to God she's found."
In a statement issued as part of the missing from home appeal, a spokesperson for Greater Manchester Police said: "Officers are becoming increasingly concerned about Christine and want to make sure she is safe and well.
"Anyone with information about Christine's whereabouts should contact police on 0161 856 7032.
"Alternatively ring Crimestoppers on 0800 555111."
Orrell Water Park is hugely popular with families, anglers, walkers and nature-lovers, covering many acres with woodland and several lakes. It is also a wildlife haven.
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