Interesting Government article on this issue including details of all relevant legislation and suggestions on how to deal with this ever increasing problem:
How to deal with dogs on the playing field is an eternal issue that many playing field managers and users face. Local authorities must take into account the fact that the community playing field is a resource for the whole community. They must therefore balance the needs of all users – people need to have access to dog free areas and areas where dogs are kept under strict control, (this especially applies to children’s play areas), but similarly, dog owners need to have places where they are able to exercise their dogs without restrictions. Dogs are in general friendly animals, providing much comfort and enjoyment to their owners, and rather than condemn dogs in general, we should look at ways for them to co-exist with the requirements of safe play and recreation.
Dogs, in themselves, are not a problem. It is the lack of control, by a small minority of owners, which causes problems. However this minority does present potential health and safety problems in areas designated for recreation and children’s play. It should also be appreciated that other pets, such as cats, can, to a much lesser extent, also present similar problems. The presence of dogs in a play area can also deter young children from using the area. Every year approximately 100,000 tonnes of dog excreta are left in public areas. This is a lot of mess to clear up and does present a health hazard.
Read the rest of the article here