finding sources of fecal coliform bacteria in stormwater ... webinar presenter...finding sources of...
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Finding sources of fecal
coliform bacteria in
stormwater runoff
David Tomasko, Ph.D.
May 12, 2016
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Why the concern over bacteria?
• Cholera
– Tens of millions killed over the centuries
– > 100,000 Americans
• 11th President, James Polk
• Typhoid fever
– Jamestown Colony
– More deaths than from battle in Civil War
Modes of transmission of typhoid (Anonymous 1939)
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John Snow and the founding of
modern epidemiology
Located ca. 10’ from
abandoned cess pit
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Two main types of bacteria
• Cocci (from Greek for seed)
– Round
• Single
• Chains
• More complex arrangements
• Bacilli (from Latin for stick)
– Rod-shaped
• Single
• Chains
• More complex
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Total coliform bacteria
• Subset of “rod or stick-shaped” bacteria
– Pathogenic (disease-causing)
– Non-pathogenic
• Why such a broad category?
– Inability of historical monitoring programs to detect
specific pathogenic bacteria (National Research Council
[NRC] 2004)
• Vibrio cholerae – cholera
• Salmonella typhii – typhoid fever
• Problems?
– Lack of specificity
– Lots of false positives
• Need for a more refined technique
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Fecal coliform bacteria
• Testing using techniques hopefully more similar to
human gastrointestinal tract
– Higher incubation temperature
• Replicating warm blooded organisms
– Bile salts
• Produced by liver
• Original derivation of 200 colony forming units
(cfu) / 100 ml
– 18% of “total” coliform bacteria from Ohio River would
test positive (NRC 2004)
– Prior standard for total colform bacteria (U.S. Federal
Water Pollution Control Administration) of 1,000 cfu /
100 ml
– 0.18 x 1,000 = 180
– Rounded up to 200 cfu / 100 ml
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Fecal coliform standard (FAC 62-302)
• Class III - monthly average less than of 200 cfu / 100 ml
– Based on minimum of 10 samples over 30 days
• Nor exceed 400 cfu / 100 ml in 10% of the samples
• Nor exceed 800 cfu / 100 ml on any one day
• Question – if monthly sampling, and value of 205?
– Not in excess of 800
– 100 % of samples, but less than 400
– Not enough samples for 200 – not impaired
• Question – if monthly sampling, and value of 405?
– Not in excess of 800
– 100 % of samples, and higher than 400 - impaired
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341 WBIDs
impaired for
fecal coliform
bacteria
179 WBIDs
with TMDLs
for fecal
coliform
bacteria
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Important considerations
• Fecal coliform bacteria are indicators of
contamination by pathogenic organisms
– Bacteria such as Salmonella sp. (typhoid), E. coli
(gastroenteritis), Vibrio sp. (cholera)
– Viruses such as enteroviruses, Hepatitis A
– Parasites such as Giardia sp., Cryptosporidium sp.
• Used for decades as more precise indicator of
threat of contamination than total coliform bacteria
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However…
• Fecal coliform bacteria can survive and multiply in
sediments to numbers far higher than in original
dosage from sewage
• (LaLiberte and Grimes 1982, Ksoll et al. 2007)
• Klebsiella pneumoniae
– Normal constituent of human intestines
– But also a natural constituent of soils
• (Caplenas and Kanarek 1984)
• Fecal coliform bacteria do not have to come from
feces, whether human or animal
– (Roll and Fujioka 1997)
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“Fecal” coliform bacteria in the Miami
River watershed
“Potential sources can include non-human fecal material, decay of
vegetation (both native and non-native) and naturally occurring soil
bacteria.” (Wagner Creek TMDL; FDEP 2006)
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Situation in Sunshine Lake
• Hypereutrophic lake in Charlotte County
• Massive algal bloom of benthic-associated
cyanobacteria
• Public demand to “do something” led to dredging
of lake
• Concurrent and ongoing work to determine the
source(s) of nutrients that enabled the algal
bloom to form
– Ambient water
– Groundwater sampling
– Bottom seepage
– Surface water runoff
• Nutrient species (nitrogen and phosphorous)
• Bacteria as potential indicator of sewage
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Hypothesis and Findings
• If fertilizer a source
– Elevated nitrogen and phosphorous, moderate bacteria
• If sewage a source
– Elevated nitrogen and phosphorous, high bacteria
• If combination – both nutrients elevated, bacteria
moderate to high
• What was found -
– Extremely high levels of phosphorous
– Average to below average levels of nitrogen
– Very high levels of fecal coliform bacteria
• (> 1 million cfu / 100 ml)
• How to explain findings?
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Interpretation of findings
• Elevated phosphorous from influence of
phosphorous-rich soils (adjacent to Bone Valley
Formation)
• Low nitrogen indicates lack of sewage and/or
fertilizer influences
• But what about elevated bacteria?
– Source Molecular Laboratories (Miami)
• Used in FC TMDL for Wagner Creek (FDEP 2006)
• 3 locations sampled twice
• ESP gene of Bacteroidetes bacteria for humans
• Maximum frequencies for humans and dogs
(combined) of less than 1%
• So where did those bacteria come from, if not
from humans or dogs??
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Follow up
steps
• Consistent with
guidance from FDEP
(2011)
– Work with Utilities to
determine possibility
of wastewater
problems
– Walk the WBID
• Some evidence of
dog feces
• Locations with
bare soils
• LOTS of grass
clippings
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Experimental design
• Four treatments with three replicates each
– 50 grams of dog feces
– 50 grams of bare soil
– 100 grams of grass clippings
– Controls
• 12 five-gallon buckets held in an abandoned
trailer with no AC or fans
• Ambient lake water with added materials
• Project done from June to July 2015
• Fecal coliform bacteria sampled (APHA standard
methods by NELAC-certified laboratory) on days
0, 2, 4, 8, 16 and 30
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Overall set up
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Dog feces Soil
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Grass clippings Controls
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So, what did we find??
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Interpretation
• Elevated “fecal coliform” bacteria sources
– Not from sewage
– Not from soils
– Less so from dogs
• Microbial source testing and Walk the WBID
• Although can be a source, obviously
– Mostly from grass clippings
• Not fecally-contaminated grass clippings
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Implications for Charlotte County
• Sewage not the source of bacteria
– No need to “fix” the sewage collection system
• Dogs could be a source
– Public education
• Soils not likely a source
• Grass clippings likely a source
– Public education
– Consistent with existing literature
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Broader Implications
• > 150 TMDLs for fecal coliform bacteria in Florida
• > 300 WBIDs “impaired” for fecal coliform bacteria
• But…
– Fecal coliform bacteria not specific to humans
– Not specific to mammals
– Not specific to animals, even
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How much of an issue is non-human
sources?
• 150,000 to 290,000 cfu / 100 ml in two “events”
from White Ibis in Clam Bay, Collier County
(Atkins 2012)
• Based on average, one bird could cause 120,000
gallons of water to exceed shellfish harvesting
limit of 43 cfu / 100 ml
• 850 birds could produce enough fecal coliform
bacteria (every day) to “impair” the 150 million
gallons of Class II waters of Clam Bay
• On a larger scale….
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Bird-related fecal coliform bacteria loads to
Malibu Lagoon, CA (Malibu Creek TMDL; US EPA)
0
400
800
1,200
1,600
2,000
Nu
mb
er o
f b
ird
s o
bse
rved
0
50
100
150
200
250
300
350
400
Feca
l co
lifo
rm b
acte
ria
load
(b
illio
n /
day
)
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Draft revised criteria from FDEP (10/2013) • Class II –
– Based on 5 samples per month
– Geometric mean not to exceed 35 Enterococci cfu / 100 ml
– No more than 10% to exceed 130 Enterococci cfu / 100 ml
– Supplements Fecal Coliform Bacteria standard
• Class III freshwater –
– Based on 5 samples per month
– Geometric mean not to exceed 126 E. coli cfu / 100 ml
– No more than 10% to exceed 410 E. coli cfu / 100 ml
– Replaces Fecal Coliform Bacteria standard
• Class III marine –
– Based on 5 samples per month
– Geometric mean not to exceed 35 Enterococci cfu / 100 ml
– No more than 10% to exceed 130 Enterococci cfu / 100 ml
– Replaces Fecal Coliform Bacteria standard
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Have we solved the “false positive”
problem?
• But…these indicators can also survive and grow
associated with decomposing vegetation (like
“fecal” coliform bacteria)
• (Byappanahalli et al. 2003, Whitman et al. 2003)
• Has anyone already switched to these new
standards?
• What did they find??
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Summary from Moore et al. (2007)
• Epidemiology studies in 70’s and 80’s show good
correlation between enterococcus concentration
and bather illness in sewage-impacted water
• Partly in response –EPA recommends (1986)
enterococcus be used as salt water indicator
• In 1999, California required testing recreational
waters for Enterococcus (in addition to Fecal
Coliform bacteria)
• So, fewer false positives??
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Moore et al. (2007)
What??
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While sewage is dominated by “fecal” Enteroccci
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Urban stormwater runoff is equally influenced
from decomposing vegetation
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Even split in oceanic waters
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Experience in Southern California
• Shift to use of Enterococci as primary indicator of
bacterial impairment in 1990s
• Resultant 5-fold increase in impairment
determinations
– 60% of which were exceedances of Enterococci, not
Fecal Coliform bacteria
• Sewage is itself associated with Enterococci
species that are 90% associated with fecal input
• Urban runoff can be equally dominated by
Enterococci species that are associated with
decomposing vegetation
• Oceanic bathing waters were influenced equally
by fecal material and decomposing vegetation
• Even if fecal sources – not proof from humans
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Potential implications in Florida
• Class II waters – potential increased frequency of
impairment
• Class III freshwater – likely a decreased
frequency of impairment
• Class III marine – potential increased frequency
of impairment
• How to respond to “impairment”?
– Don’t MODEL it – not enough real data
– Walk the WBID – look for potential sources
– Where appropriate, source identification
• Don’t just assume it’s from humans
• Doesn’t have to be from humans to be a problem