At Huntington, nowcasts were provided to the public for 106 days during the recreational season of 2008.

• The nowcast provided a correct response 85 percent of time.
• False negative responses from the nowcast were provided 43 percent of time. That means that the nowcast incorrectly predicted that the standard was not exceeded on 6 out of 14 days that the standard was actually exceeded.
• False positive responses from the nowcast were provided 11 percent of time. That means that the nowcast incorrectly predicted that the standard was exceeded on 10 out of 92 days that the standard was actually NOT exceeded.

The Huntington nowcast provided more accurate information and better estimates of public health risk than the use of the previous day’s E. coli (the current method used by most beach managers.), especially in regard to reducing false negatives.

• The previous day’s E. coli provided a correct response 75 percent of time.
• False negative responses using the previous days E. coli were provided 93 percent of the time. That means that the current method incorrectly predicted that the standard was not exceeded on 13 out of 14 days that the standard was actually exceeded.
• False positive responses using the previous days E. coli were provided 14 percent of the time.

At Edgewater, nowcasts were provided to the public for 118 days during the recreational season of 2008.

• The nowcast provided a correct response 61 percent of time.
• False negative responses from the nowcast were provided 68 percent of time. That means that the nowcast incorrectly predicted that the standard was not exceeded on 28 out of 41 days that the standard was actually exceeded.
• False positive responses were provided 23 percent of time. That means that the nowcast incorrectly predicted that the standard was exceeded on 18 out of 77 days that the standard was actually NOT exceeded.

The Edgewater nowcast did not provide more accurate information than use of the previous day’s E. coli (the current method used by most beach managers.), especially in regard to reducing false negatives.

• Many of the false negatives in the nowcast were due to significantly higher lake levels in 2008 than those found in the data used to develop the models (2004−07). Because of the negative relation between E. coli concentrations and lake levels for 2004−07, the model was underpredicting the probability that the standard was exceeded during 2008. To find out more about lake levels, see the full report.
• The previous day’s E. coli provided a correct response 57 percent of time.
• False negative responses using the previous days E. coli were provided 62 percent of the time.
• False positive responses using the previous days E. coli were provided 37 percent of the time.