Spyglass participated in the February Beach Water Quality Workgroup (BWQW) meeting held in Alameda, CA. Initially formed by the State Water Resource Control Board (SWRCB) in 1998, the BWQW facilitates coordination of beach water quality related monitoring, pollution abatement, public education, and public notification efforts. The BWQW holds quarterly meetings in both Northern and Southern California locations.
Source - Flickr: kansasphoto
Method Study for Total ColiformIn addition to addressing BWQW agenda items, these meetings are an opportunity in which presentations are given to an audience that included water quality managers, water specialists, and other parties interested in the state’s beach water quality. One presentation from this recent meeting was a study that compared total coliform results produced by a rapid test against results using more traditional methods. Since the use of rapid methods is desirable to facilitate timely closure or reopening of recreational beaches, this presentation highlighted pros and cons of using a rapid test method for recreational beach water monitoring.
The lab for East Bay Municipal Utility District (EBMUD) presented the results of a 2009 study that examined the discrepancies between results produced by a rapid enzyme-based detection method versus the traditional method of Multiple Tube Fermentation (MTF). The rapid test used in this study was designed in an “easy-to-use” format that produced results within 24 hours. The MTF protocol requires several more steps and the time-to-results is 2 to 3 days. Both methods provide presence/absence and a most probable number (MPN) measure of bacteria density.
Multiple Tube Fermentation. Tubes in center and right are positive for fermentation (gas bubble). Source: John Lindquist, U. of Wisconsin-Madison
During the study period, samples were taken daily from two ambient freshwater lakes and were analyzed for Total Coliform (TC) using both the rapid method and MTF. Simultaneous enzyme tests were also conducted on the samples to identify the bacteria present in the water.
When the data for both methods were compiled, the results proved quite dissimilar. In Lake “A,” the rapid method had higher results than MTF in 66 of 67 samples tested. Seventy-nine percent (79%) of these rapid method results were greater than 2400 MPN/100mL, whereas 100% of the MTF results were less than 250 MPN/100mL. For Lake “B,” the rapid method results were higher than MTF results in 51 out of 54 samples, with 43% being at least an order of magnitude higher.
Upon further analysis, EBMUD found that in Lake A, MTF produced false negatives when the test did not detect the coliform Enterobacter amnigenus. In Lake B, the rapid test produced false positives detecting non-coliform Aeromonas hydrophila. These false positives occurred as a result from how the rapid test detects coliforms. The rapid test uses a nutrient indicator that can be metabolized only by bacteria that produce the enzyme beta-galactosidase. The rapid test contains suppressing agents for many beta-galactosidase-producing non-coliforms; however, the lab discovered that the test was known to have the potential for false positives in environmental samples, especially with Aeromonas.
The EBMUD lab concluded that while the rapid test offered faster time-to-results and could detect coliforms not detected by MTF, more specificity and accuracy was desired in their beach water monitoring.
Water Quality Indicators and qPCR
Since 2009, the EPA has chosen bacterial indicators other than TC for setting water quality objectives. The EPA Draft Criteria for Recreational Water Quality sets objectives using E. coli and Enterococcus. As a result, many participants at the BWQW meeting recommend dropping TC from recreational water quality monitoring since TC is not specific enough in determining the health risk associated with the sampled water.
In order for labs such as the one at EBMUD to adopt a new testing method, the method must identify E. coli and Enterococcus with increased accuracy AND faster time-to-results. As a new method supported in the Draft Criteria, qPCR may be the solution. Quantitative Polymerase Chain Reaction, or qPCR, can provided results in hours versus days and the data are highly specific.
Magnified view of Enterococcus facaelis bacterium. Source: US Dept of Agriculture
Spyglass and the Future of Water Quality Testing
The Spyglass Environmental Sample Processor has been used in a recent recreational water quality study (see blog). Data from this study are currently being complied and another ESP deployment during the summer beach season is planned. With actionable data from the ESP, beach managers can proactively protect public health and community interest. Additionally, Spyglass offers qPCR test kits for several waterborne bacteria. These kits also allow customers to evolve testing based in the lab into the field.
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