Treat a covered pool as open water
The danger of a pool cover is that it lies to everyone. To you it signals the pool is closed; to your dog it can look like a new piece of solid garden, a place to chase a ball across or lie in the sun. Many covers dip under even a medium dog's weight, collecting water on top, and a dog who goes through or slips under an edge can become trapped out of sight, unable to climb out on a slippery surface while the cover folds around her. Strength ratings for debris or a child's brief step do not make a cover a safe walking surface for an animal who may panic and thrash. The only honest starting point is this: covered or not, the pool is water, and water needs a barrier.
Make the barrier physical and foolproof
Fence the pool area or gate every route to it, with a self-closing gate that latches where a dog cannot nudge it open, and check the full perimeter for gaps a determined dog could squeeze under or jump. If fencing is impossible in your layout, the dog simply does not have unsupervised access to that part of the garden — she goes out on a lead or long line, or uses a separate fenced area for free play and toileting. Keep balls, toys and her favourite sunbathing spot far from the pool edge so her habits do not draw her toward it, and store the cover mechanism and chemicals out of reach. Brief every human who uses the garden, including gardeners, cleaners and visiting children, because barriers fail at the moment a helpful person props a gate open.
Train the boundary as backup, never as the fence
Alongside the physical barrier, teach her that the pool zone earns nothing and leaving it earns plenty. Practise recalls and a settle on a mat well away from the edge, reward heavily for choosing the far lawn, and interrupt any drifting toward the cover calmly and early, before she is on it. Teach her the safe way out of the water itself in controlled conditions if your vet and a suitable trainer agree it is appropriate for her — many dogs benefit from knowing where the steps are — but never throw her in or let her rehearse falling in. If she does get onto the cover or into the pool, keep your own rescue safe: call her to the steps or edge, reach from firm ground, and get urgent veterinary help afterwards even if she seems fine, since water inhalation can cause problems hours later.
Build the rule into ordinary days and busy days alike
Risk peaks when routine slips: a barbecue with the gate hooked back, children running between house and pool, a ball that bounces the wrong way, a dog left in the garden while everyone swims. Decide in advance who is the designated dog watcher during gatherings, rotate the role, and settle her indoors with a chew when supervision gets thin. Keep a towel, a charged phone and her vet's number by the back door as part of the furniture of pool life, and practise opening the gate, calling her away and latching it behind you until it is muscle memory for the whole family. KinsLe Family Sharing keeps the gate rule, her watcher rota for gatherings and what to do after any fall into the water on her profile, so a guest or a new babysitter inherits the safety routine, not just the house keys.