Reservoirs Under The Big Thompson River and Tributaries, Colorado.
A good map from the turn of the century that looks at the drainages, reservoirs and irrigation ditches. Spans from west of Loveland and Berthoud, east to Greeley and LaSalle. Separates regions by land "irrigated from independent sources", or those "in discussion". A great little reference.
Condition is very good. Image size is approximately 8.25 x 13.25 (inches)