Cryptosporidium incidence and surface water influence of groundwater supplying public water systems in Minnesota, USA

Environmental Science & Technology
By: , and 

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Abstract

Regulations for public water systems (PWS) in the U.S. consider Cryptosporidium a microbial contaminant of surface water supplies. Ground- water is assumed free of Cryptosporidium unless surface water is entering supply wells. We determined the incidence of Cryptosporidium in PWS wells varying in surface water influence. Community and noncommunity PWS wells (n = 145) were sampled (n = 964) and analyzed for Cryptosporidium by qPCR and immunofluorescence assay (IFA). Surface water influence was assessed by stable isotopes and the expert judgment of hydrogeologists using site-specific data. Fifty-eight wells (40%) and 107 samples (11%) were Cryptosporidium- positive by qPCR, and of these samples 67 were positive by IFA. Cryptosporidium concentrations measured by qPCR and IFA were significantly correlated (p < 0.001). Cryptosporidium incidence was not associated with surface water influence as assessed by stable isotopes or expert judgment. We successfully sequenced 45 of the 107 positive samples to identify species, including C. parvum (41), C. andersoni (2), and C. hominis (2), and the predominant subtype was C. parvum IIa A17G2R1. Assuming USA regulations for surface water-supplied PWS were applicable to the study wells, wells positive for Cryptosporidium by IFA would likely be required to add treatment. Cryptosporidium is not uncommon in groundwater, even when surface water influence is absent.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Cryptosporidium incidence and surface water influence of groundwater supplying public water systems in Minnesota, USA
Series title Environmental Science & Technology
DOI 10.1021/acs.est.8b05446
Volume 23
Issue 7
Year Published 2019
Language English
Publisher American Chemical Society
Contributing office(s) Upper Midwest Water Science Center
Description 8 p.
First page 3391
Last page 3398
Country United States
State Minnesota