Otters, Girls, and Witches

Three sisters live on a country estate with acres of woodland, a walled garden and an orchard. There is a pretty glade in the middle of the forest with a waterfall and pool where the girls learn to swim on warm days.
Their father works on the estate as groundsman and the girls have this massive wilderness all to themselves: or so they thought!
It's hard to imagine who or what is behind the waterfall?
The sisters are super excited on the day their mother goes into hospital to have a baby, and, the girls are left to their own devices.
You will meet the three otters and learn their crucial role in the story.
Let me introduce you to the three girls.
Bunty, age nine, has glorious, red curls and the loudest voice.
Marjory is ten years and loves reading and learning.
Susy is twelve and, being the oldest, is smart and full of fun.