Ron:
There is no doubt that Watson was involved, but all signs point to his work taking place later.
Here's a brief synopsis of both courses at Wanakah (if there's more to add to the story I'd love to see it):
First Course (opened sometime in 1901 or before, Arch. Unknown)
1902 SOGG Directory of Golf Clubs notes a 9 hole course.
1905 SOGG notes a 9 hole 2,985 yard course with plans to extend to 18 holes in the future.
1907 SOGG notes plans to extend present 9 hole course to 18 holes with purchase of 200 acres surrounding the clubhouse with John Harrison as professional.
April 1915 Golfers Magazine notes Wanakah GC passed out of existence in 1912 and grounds were taken over by Wanakah CC, a new organization which built a new course.
Second Course
May 29, 1913 The Buffalo Commercial notes work on the course under the direction laid out by Donald Ross.
July 6, 1913 Cincinnati Enquirer notes recent activities of Donald Ross.
1914 SOGG notes course increased from 9 to 18 holes on newly purchased land and alterations made to the existing 9 holes.
May 4, 1919 The Arizona Republican notes Watson to rearrange the course.
June 1919 Golfers Magazine notes course remodeled by Watson.
June 22, 1919 Sunday Oregonian notes Watson remodeled the course making it modern and of championship caliber.
May 23, 1924 Buffalo Evening News notes course to be remodeled and increased to 6,440 yards using newly purchased grounds with William Watson as architect.
Undated 1925 Buffalo Express article notes opening of new 18 hole course which is the work of William Watson.
Oct. 1925 Golf Illustrated notes new 18 hole course.