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SLV Water Quality Testing Updates

Through our partnership with the University of Colorado and the School of Public Health,

spearheaded by Dr. Kathy James, the San Luis Valley Ecosystem Council (SLVEC) coordinated

a community-wide household well water sampling effort as part of the 5-year study evaluating

the impacts of drought on water quality and quantity. The well water sampling efforts

successfully recruited 862 households and have currently analyzed 736 samples from all six

SLV counties. Initial results have found elevated levels of several heavy metals that naturally

occur in groundwater systems in the SLV including arsenic (10% wells), uranium (7%),

manganese (7%), tungsten (3%), lead (2%), and copper (4%). Results also indicate most of the

wells have moderately to extremely hard water. Next steps will explore the relationship between water quality and drought indicators (snowpack, precipitation, changes in aquifer levels, and temperature) using current and historical information.

● 736 well water samples total

● Samples matched to permits maintained by the Division of Water Resources


■ Saguache County - ~181

■ Alamosa County - ~115

■ Rio Grande County - 185

■ Costilla County - ~75

■ Conejos County - ~136

■ Mineral County - ~ 20-30

Important Findings:

● 21% of samples had at least one metal above EPA recommended levels

● 4% of samples had at least two metals above EPA recommended levels

● We know that there are some metals that can have adverse effects at any level of

exposure - including lead and arsenic.

○ Note while a lot of samples do have some trace amounts of each element, the

amount of these elements present in samples is relatively low (i.e. the

percentage goes down drastically as the "amount threshold" increases).

○ Arsenic

■ Above 0 ug/L - 93%

■ Above 1 ug/L - 48%

■ Above 5 ug/L - 15%

○ Lead

■ Above 0 ug/L - 85%

■ Above 1 ug/L - 5%

■ Above 5 ug/L - 1%

Another research question is evaluating the impacts of drought on the aquifer system,

accessibility of water, and water quantity. Researchers are currently: mapping the risk

probability of arsenic occurrence, evaluating whether subsidence is occurring using satellite

data, and mapping recharge efficiency. Researchers are now producing maps to determine the probability of a well having arsenic levels above 5 ug/L. At this level and with chronic use, long term health impacts can occur. Researchers are using satellite data to evaluate where and if subsidence is occurring. Subsidence is the compaction of soil structures within an aquifer with withdrawal of water such that water cannot be recharged. Preliminary findings suggest that subsidence is occurring however not at the rate seen in areas such as California. Research is ongoing and as we receive more results, we will send them to the community. There will be more summaries about this overall project soon.

Thanks to all those who participated and contributed to this valuable research.

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