Seasonal contamination found in Upper Pecos River

By Teresa Seamster, New Mexico Water Sentinels, from the spring 2024 newsletter

For years, northern group volunteers have been monitoring four key sites on the Pecos River from Willow Creek tributary – that flows through the old Tererro Mine reclamation property – 14 miles down to the town of Pecos. Last year the analysis included looking at total metals, gross alpha and the presence of nutrient contaminants.

As the tests were more comprehensive in 2023, we can now see some undesirable trends in the upper Pecos River:

Total Metals – Elevated levels from July-August-September samples

• Calcium – U.S. average in drinking water is 10-20 mg/L
  Tererro-59 mg/L; Indian Creek-55 mg/L; Dalton Camp-37 mg/L; Pecos Bridge-40 mg/L
• Aluminum – health effects can occur at >0.05 mg/L
  Tererro-0.33 mg/L; Indian Creek-2.5 mg/L*; Dalton Camp-0.16 mg/L; Pecos-0.25 mg/L (* high spike, Indian Creek averages 0.15 mg/L)
• Iron – objectionable >0.3 mg/L, health effects 10 mg/L
  Tererro-0.4 mg/L; Indian Creek-3.1 mg/L
• Lead – minimum reporting level 0.001 mg/L
  Tererro-0.002 mg/L; Indian Creek-0.003 mg/L
• Other metals analyzed: Boron, Magnesium, Manganese, Antimony, Arsenic, Barium, Beryllium, Cadmium, Chromium, Cobalt, Molybdenum, Nickel, Selenium, Silver, Thallium, Uranium, Vanadium & Zinc (all below MRL)

Gross Alpha/Beta (radioactive elements) – All samples were below National Drinking Water Standards for Gross Alpha – 15 pCi/L but detectable at all sites

• Elevated Gross Alpha (SDL is the NM State Detection Level)
  (SDL 0.6) Tererro-0.9pCi/L; (SDL 0.7) Indian Creek-4.9 pCi/L
• Elevated Gross Beta
  (SDL 1.7) Indian Creek-4.9 pCi/L; (SDL 1.9) Dalton Camp-5.1 pCi/L, (SDL 1.5); Pecos-3.2 pCi/L

Nutrient Levels, often found in run-off from agricultural fields and livestock, showed slight elevations of nitrogen and phosphate at all sites, but all ammonia levels were acceptable.

Unfortunately, E. coli levels were elevated at all sites, ranging from low to high during the summer months. According to the World Health Organization – safe drinking water should have NO E. coli present

• 1-10 MPN/100ml = low risk/ 11-100 = medium risk/ > 100 = high risk
• Highest E. coli site – Tererro 209.8 MPN/100mL
• Lowest E. coli site – Dalton Camp 9.7 MPN/mL
• The upper Pecos River is still showing signs of acid mine drainage from the massive mine contamination left over from the Tererro Mine of the 1930s. The water is also showing significant impacts from unregulated sources of E. coli along the tributaries. However, the main river E. coli levels at Dalton Camp and Pecos bridge average in the low-medium risk category.

Thank you to Amigos Bravos and to Water Sentinels: Ginny Seamster, Tannis Fox, and Trout Unlimited: John Lopez.