Evaporation from the farm pond

I am from Asia and after working in industries for 10 years have switched to farming in my area. The area where I live   receives an average of 950 mm rainfall annually and has good potential for run-off harvesting. So I decided to go for a farm pond. Considering the slopes of the fields, an appropriate location was identified for a dug out pond (8m x 8 m x 3 m). We have taken a good care for pitching so the percolation is very less but the evaporation is very high. Can anyone suggest me some economic ways to reduce the evaporation from our farm pond?