Figure 2: Outgrowth of a second, non-Yersinia pestis species from Niagara River water following inoculation with Y. pestis reported in CFU/mL as a function of time (days). The concentration of Y. pestis (♦) and unknown (■) were monitored by colony enumeration from TSA II plates. The dotted line depicts where the number of CFUs/mL were too numerous to count. The standard deviation falls below 50% of the plotted value for all calculated points.