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of Colorado is the Division of Minerals and Geology (DMG). Colorado State Senate Bill 95-156, Section 1, Title 34, Article 32.5, part 34-32.5-116 paragraph 4(h) states that an operator shall minimize "disturbances to the prevailing hydrologic balance of the affected land and of the surrounding azea and to the quality and quantity of water in surface and groundwater systems, both during and after the mining operation and during reclamation". The DMG has provided guidance in some detail in Sections 3.1.6 and 3.1.7 of the Construction Material Rules and Regulations. In particular, part 7(b) of Section 3.1.7 outlines a monitoring protocol such as this for areas where "an adverse impact on groundwater quality may reasonably be expected". These sections are included in Appendix A of this report. As a matter of practice, the DMG has typically limited an operator's liability to insuring that a quantity and quality of water in surrounding wells within 600 feet of the permit boundary is maintained. The DMG enforces this by requiring that existing wells be deepened, or a new well drilled for locations where an adverse impact is noted. This combination of corporate, public, and government interest creates the framework for building a monitoring network and creating useable information. From this standpoint a definition of water quality in this context may be as follows: • The ability to pump water from existing irrigation wells at a particular quantity and quality and/or provide adequate sub-irrigation such that lawn cover or pasture grass yields aze not substantially affected. • The condition of groundwater levels relative to septic leach fields, generally located 2-3 feet below ground surface. • The level of surface water in unlined (groundwater fed) ponds as necessary to create and maintain attractive appearance. It is generally agreed that measurement of groundwater depth in a group of existmg irrigation and monitoring wells can act as a surrogate for these water quantity variables. General indicators of conductivity (dissolved solids content) and pH (acidity) serve as measures of the water quality condition. Therefore these three variables will be measured I as aggregate indicators of water quantity and quality. These variables can be measured to determine several things. The first is to create information about the baseline or existing condition. Once dewatering begins, a new condition will exist. These values can be compared to previous, baseline measurements to indicate whether a significant change has occurred. Finally, this process can be L repeated at such time as the reclaimed pit might be lined to determine any change in surrounding water quantity or quality after that event has occurred. The determination of these averages and trends should include some allowances for the highly seasonal nature of groundwater levels. It is important also to note that although 3-4 years of data maybe available prior to the start of mining, it is likely that some conclusions may need to be drawn much sooner after the commencement of mining. This will affect the margin of error present in the analysis.