Science Center Objects

Illinois Gulch, near Breckenridge, Colorado, is on the State of Colorado 303(d) list of impaired waters because of elevated concentrations of cadmium and zinc.  Cadmium and zinc concentrations exceed chronic aquatic life standards in the upper portion of Illinois Gulch, and pH is circumneutral.

Water quality deteriorates further in the lower portion of Illinois Gulch, as water from a metal-rich tributary, Iron Springs Gulch, enters along Boreas Pass Road. 

Sources of metals and acidity to Iron Springs Gulch include:

  • Two draining adits: Willard Adit 1 and Willard Adit 2
  • Little Mountain Spring which includes drainage from the Germania Mine
  • A large waste dump.

Willard Adit 1 receives drainage from the collapsed Willard Tunnel, the main haulway for the Puzzle Mine.


Determine the degree of hydrologic connection between the upper portion of Illinois Gulch and Willard adits 1 and 2.  

An October 2015 study conducted by the State of Colorado suggests a loss of flow from upper Illinois Gulch in the vicinity of the Puzzle Extension Shaft.  This data, together with existing knowledge of the underground workings, suggests a possible connection between upper Illinois Gulch and Willard Adit 1, with the Willard Tunnel serving as the primary conduit.  In order to minimize downstream effects of these draining adits, it may be desirable to implement hydrologic controls which prevent Illinois Gulch water from entering the mine workings.  The possible connection between the gulch and the mine workings will be explored through a multi-tracer approach.