The reservoir and its protective margins covered an area of about 65,000 acres ( 260 km2 ) .
To secure this , it was necessary to purchase a total of approximately 100,000 acres ( 400 km2 ) of which approximately 75 % was woodland .
The reservoir and its protective margins covered an area of about 65,000 acres ( 260 km2 ) and to secure this , it was necessary to purchase a total of approximately 100,000 acres ( 400 km2 ) of which approximately 75 % was woodland .