I have a large lined pond - probably 40 ft. by 20 ft and 6 ft deep in the deepest part. We are in a drought area and feel bad about the water (although we need some use to keep rights active). Also find it really expensive to maintain and keep healthy. I have heard that it is difficult to make a pond smaller - would like to reduce to maybe 10 ft. by 10 ft. Does anyone know if it can be done? Thanks