This is a natural area of very boggy grass, the only thing we could do really was turn it into a bog pond. The water rises and falls depending on the water table and weather, when we first moved in there had been heavy flooding so the water table was very high.
Another shot of the bog pond, we made a small patio out of flag stones found by the house, the blue balls were a present from m'spouse. Some of the plants have been relocated from the pond up by the house, along with the newts and toads found there.