|Honeybee visiting peach flower|
A. The bees are looking for water to take back to their hives. When it is hot out, bees are continuously hauling water back to the hives to keep it cool. And consequently they drown because the pool is not shallow.
She can try putting out a shallow depression in the landscape away from the pool and see if they will land there instead. They would prefer to haul water from a place that has a very shallow amount of water like the edge of a pond or stream.
This way they can land on solid ground, take water and fly away. Once they find it, they may make lots of trips to it for water and be regular visitors. There is a hive somewhere fairly close by.