1901 Map of the Big Thompson

In 1901 the United States Department of Agriculture published a yearbook that contained a map of the “Reservoirs under the Big Thompson River and Tributaries.” Since the Little Thompson River that flows near Berthoud is a tributary of the Big Thompson River, the map shows lakes and ditches in the Berthoud area. While there are mistakes and misspellings on the map, it more or less accurately shows the early courses of the Home Supply and Handy ditches that deliver irrigation water to Berthoud’s farms. Both ditches now extend further into the Johnstown area.

The Home Supply and Handy ditches began diverting water from the Big Thompson River in the early 1880s in order to supply summer irrigation water to local farmers and year-round domestic water to the fledgling towns of Loveland and Berthoud. When feasible, farmers “under” the ditches constructed small reservoirs where they could store irrigation water for use on their farms throughout the summer. Prior to that time irrigation water was only available in the spring and early summer when mountain snow-melt caused the Big Thompson River to flow at a high level.

Of note is the cluster of Welch Reservoirs at the left center of the map. While the lakes were separate entities when the map was published in 1901 by 1905 the process of consolidating them into one body of water was underway. That year the lakes were purchased by the Handy Ditch Company at a cost of $10,000. The Berthoud Bulletin noted, “Last spring enough water went to waste down the Big Thompson to irrigate Northern Colorado for several years. By increasing the storage capacity of our lakes a great amount of water can be saved. The Welch Lake can be diked up as to greatly increase its capacity.”