Four samples were collected between 6:00 a.m. and 7:00 a.m. on July 15, 1997. Sample water was taken from two sites on Carnegie Lake. The first site was from the boat dock directly in front of the flag pole on the Princeton University Boat House. Midway between the boat house and Washington Road is a small dock from which the second lake sample was taken. Two samples were also collected from the Delaware and Raritan Canal at locations that corresponded to the collection sites on the lake.
The collection was done by submerging 500 ml drinking water bottles to a depth of approximately 7 cm, allowing the bottle to fill, emptying the water that filled the bottle, and repeating the filling process at the same depth of 7 cm.
The following day, July 16, two additional samples
were taken between 6:00 a.m. and
7:00 a.m. Trying to find a location where water naturally enters Carnegie Lake, these samples were taken west of Alexander Road. Again, collection sites were corresponding points on the stream and canal. The method for filling the collection bottles mimicked the previous day's.
At each sampling site the time, temperature, and location were recorded. After collecting a sample, five tests were conducted at the site.
Testing for Escherichia coli requires inoculation and incubation. The Easygel™ media are designed for easy inoculation, a shorter incubation period than with traditional methods, and easy identification of E. coli bacterium colonies. The water samples were returned to the laboratory facilities within an hour of collection. Three milliliters of sample water was added to the Easygel medium, the resulting solution was mixed by swirling the Easygel bottle, and the water/medium mixture was plated on a petri dish. Identification of the E. coli colonies was made after thirty-six hours.