2015-03-18_HYDROLOGY - M2012032 - Laserfiche WebLink

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growth rate for the next 50 years. Based on this population growth, the total water demand for 2063 was estimated to be 2.52 cubic feet per second, or 1,825 acre -feet per year [3]. Weehawken Spring, the city's current water source, has a permitted diversion rate of 3.82 cubic feet per second [3]. This water right exceeds the projected future domestic use requirement, thus, using Revenue groundwater is not expected. Additionally, the city has other water rights that are reserved for future use. In total, the city has water rights summing to 12.8 cubic feet per second [3]. The reserved for future use water rights are all from surface waters that are not in an area that the groundwater near the Revenue Mine could potentially impact. The surface waters are also not impacted by Sneffels Creek. It is also not probable that the Revenue groundwater will be used for domestic use because background levels indicate that the water does not meet Human Health Standards. A full table outlining the human health standards used by the CDPHE are shown in Appendix G. The parameters that are exceeded by the current groundwater based on the first round of well sampling are dissolved antimony and dissolved manganese. The CDPHE human health standard for dissolved antimony is 0.6 WJL and the maximum amount found in the groundwater wells was 2.7 WJL. This can be considered a significant exceedance. Dissolved manganese had an exceedance in which the CDPHE human health standard is 50 WJL and the maximum amount found in the wells was 54 WJL. CDPHE Agricultural Use Groundwater Standards As the ground water in the Revenue Mine area cannot be classified as domestic use or domestic use quality, an analysis on whether the water can be classified for agricultural use must be assessed. Under Regulation Number 41 section 41.4 -B -2 the criteria to classify water as agricultural use are outlined. To be classified for agricultural use or agricultural use quality, one or more of the following must be met within the specified area: ground water is used for agricultural use, there is reasonable potential for future agricultural use of groundwater, groundwater is permitted or decreed for agricultural use by the State Engineer or applicable water court, and /or background levels are generally adequate to meet the CDPHE agricultural standards. The CDPHE in- stream standards classify the affected segment of Sneffels Creek for aquatic life, recreation, and agriculture. Because it is unknown whether the groundwater interacts with Sneffels Creek, it is safe to assume that these classifications also hold for the groundwater. This indicates that the groundwater meets the first and second criteria for agricultural use classification as water that is currently used and also has probable future use for agriculture. The State of Colorado breaks down its water courts into six divisions based on County, of which the Revenue Mine is classified as Division Four [4]. An examination of the past year of Division Four water court cases indicates that the majority of cases deal with surface water. There are a very limited number of cases referring to groundwater, none of which have groundwater from wells but instead spring -fed water. Of the court cases in Ouray County, the majority of cases cover water with classified uses for irrigation or stock water. Because these are agricultural activities, it can be assumed that water in the area is currently used for agricultural purposes, and will most likely remain as such in the future. Lastly, the final criteria to classify water as agricultural use of meeting the CDPHE agricultural standards is also met. A complete table showing the CDPHE agricultural standards can be found in Appendix H. The maximum concentration found in the groundwater wells meets these standards for all parameters. 13