Dovestone Reservoir will close from this evening (March 23) as official government advice to observe good social distancing is stepped up.
United Utilities has announced it is to close all its reservoir and recreational site car parks.
Concerns were raised after a huge surge in visitors to sites over the weekend.
Toilets, car parks and other gated entrances will be shut from tonight.
A United Utilities spokesperson has said: “We’re sorry to be doing this as we know these sites are enjoyed by so many and it’s not a decision we’ve taken lightly.
“We really need to think about the well-being of everyone in our communities at the moment, and that means avoiding unnecessary travel or close contact with those outside your household.
“While getting out and enjoying the fresh air is still important for us all, we need to restrict the numbers of visitors travelling to popular sites like Dovestone and Rivington.
“Over the weekend the car parks were heaving and people were mixing in large numbers.
“For that reason we are closing the car parks at all of our sites and we appeal to people not to drive to them.
“Of course, much of our land has open access and we don’t want to stop people walking in the fresh air. If you live locally you can still walk to our sites and exercise your dog, but please keep a safe two-metre distance from others.
“These are difficult times, but they won’t last forever.
“We look forward to reopening the car parks and welcoming everyone back to our estates as soon as the official advice changes.”