This study evaluated the validity of monitoring for Escherichia coli in lieu of Cryptosporidium to assess the vulnerability of source waters to the presence of Cryptosporidium oocysts. Over a period of seven years, four large water systems in Utah collected Cryptosporidium, E. coli, and turbidity data from seven water treatment plants that treat both reservoir and stream sources. The data represented analyses completed by two US Environmental Protection Agency‐approved protozoan laboratories and local state‐certified laboratories for E. coli. Results of the statistical analyses indicated poor correlation between Crypto sporidium and E. coli and between Cryptosporidium and turbidity in all monitored water sources throughout the entire monitoring period. The analyses indicate that elevated concentrations of E. coli are not indicative of the presence of Cryptosporidium in surface water. Both E. coli and turbidity are poor surrogates for occurrence of Cryptosporidium at treatment plant intakes. Further investigation is needed to establish appropriate surrogates for Cryptosporidium occurrence.