Lynne Yourston, owner of L&L Cutz said: "I couldn't believe it when I came down this morning. I could see the water pushing against the door and I knew the damage would be awful.
"Everyone has been fantastic, coming over to see if they can help us out in some way.
"The electrics are out, the floor is ruined but thankfully the stock is ok. I am hoping we can re open as soon as possible."
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The harrier, named Manu, is one of two chicks monitored and protected by the Northumberland Hen Harrier Protection Partnership.
One flood warning remains in place for Cumbria after the county was hit with a third of the rainfall that fell during Storm Desmond.
There is one flood warning and three flood alerts currently in place across the county.