Lake Size 



Description by class. - -Lakes of different sizes have different possibilities for recreational 

 use. Therefore classification according to surface area is recommended. The following five 

 classes have been found useful for mountain lakes: 



Class l--less than 1 acre 

 -. Class 2 --1. 00 to 4.99 acres 

 Class 3--5.00 to 9.99 acres 

 Class 4--10. 00 to 19.99 acres 

 Class 5 --20 acres or more 



The size class of a lake can be estimated directly on a photo by means of a lake size guide, 

 a- transparent overlay printed with concentric circles that correspond to the lake size classes at 

 the average scale of the photos being examined. By placing the guide over a lake image on a 

 photo, the interpreter can rapidly select the size class most nearly matching the lake surface 

 area. It should be remembered that division of lakes into general size classes with the guide is 

 merely an approximation of acreage. The acreage of a long, narrow lake, for example, cannot 

 be accurately measured with a circular guide, but a reasonable estimate can be quickly made. 



Description by acreage. - -When it is deemed necessary to describe lake size more pre- 

 cisely than by classes, each lake image can be measured with a dot grid. This grid is a trans- 

 parent overlay covered with equally spaced dots, each of which represents the center of a small 

 square. For most lake measurements, a dot grid having 256 dots per square inch is adequate. 

 Where added precision is desired, a microdot grid having 1,024 dots per square inch can be used. 



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