The
Beach Act of 2015 as proposed will be requiring faster
water-quality testing and reporting. But qPCR
test results won't be made available to the public a couple of hours
after sampling.
After
a sample is taken, the remaining samples in that inspectors 'run' –
about 2 hours - will have to be completed. Then they will be driven
to the lab, where they can be held within the methods allowable time
frame, then processed and analyzed. Then results will be reported to
the health deparment, and subsequently posted on the health deparment
and state websites.
So,
more like mid to late afternoon for results.
That's
still, much faster than the current 24-hour delay for getting
culture-based
results back from the lab. The present laboratory
method counts live bacterial colonies growing in a culture for
about 24 hours. QPCR only takes a few hours because it measures
bacterial DNA – from live and dead cells - rather than cell
growth.
Getting
test results a few hours after sampling will be transformative. When
the method is reliable.
Here
are some reasons why the qPCR method is still a work in progress: the
lack
of a formal standardized
method protocol for laboratories using the 2013 EPA
methods. The EPA research primarily studied beaches impacted
by sewage, not stormwater. qPCR measures dead as well as live
cells, so it can test higher
than the culture-based
methods that count cell growth. And lower,
when PCR
inhibitors in the water sample – like humic and tannic
acids from decaying vegetation in surface water – cause
amplification
failure.
As
these issues are worked out, fundamental change can come by also
using predictive
models to forecast beach water quality.
Forecasting
water quality every day of the week is a cost-effective supplement to
sampling. It's been done for years at beaches along
the Great Lakes. California began testing their Water
Quality Nowcast at three marine beaches this summer.
Weekly
sampling is expensive. Public
Health has not done well since the recession. More sampling
after storms and inadequate federal funding will mean higher
state and local taxes, mostly for manpower.
That's
why the EPA has been nudging states to use
forecasting models to supplement their water sampling since 2012.
Previous
blogs about forecasting marine water quality:
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