The reservoir, Upper Klamath Lake, is for the most part a natural lake that covers an area of 85,000 acres at reservoir water surface elevation 4143.3.
(The reservoir; is; for the most part a natural lake) (a natural lake; covers; an area of 85,000 acres at reservoir water surface elevation 4143.3)
The reservoir a natural lake
is covers
for the most part a natural lake
an area of 85,000 acres at reservoir water surface elevation 4143.3