Figure 1
shows the change in the total coliform levels from November to February. The
levels of total coliforms rose from November 2006 to December 2007 for three of
our testing sites, the bridge, beach and pier. Total coliform levels remained
the same in November and December at the park site. In January, total coliform
levels drastically dropped at three of our testing sites. We were unable to test
at the bridge site in January because the water was frozen to the bottom of the
lagoon, so we are not able to report any data. In February, all four sites
contained minimal amounts of coliform bacteria.
Figure 3 shows the average number of geese at the bridge and beach sites before and during each of our testing months. The beach site (zone 8) contained 75 geese at the beginning of October and then none through the last counting date. The bridge site (zones 3, 4, 5 & 7) contained many more geese than the beach site and therefore likely more goose feces that contaminated the site with E. coli. We did not obtain or count geese at the pier or park sites.
Figure 4 compares average E. coli levels taken during the summer months by the Madison Department of Public health at the Vilas Beach with results done by previous Natural Science groups (Bruesewitz et al, 2005) and the E. coli levels results we obtained with our research project. During the summer months E. coli levels were the highest and when the lake was frozen over (winter months) E. coli levels consistently drop to <1 MPN. Note the high levels in December 2006.