Presentation on theme: "Enterococci in the Hudson River"— Presentation transcript:
1Enterococci in the Hudson River What is it?What does it tell us?How does it get in the river?How do we test for it?What can we do about it?PPT adapted from the summer 2007 research ofSuzanne Young, Barnard graduate. Project funded by The Hudson River Foundation through a Polgar Fellowship. (adapted by M. Turrin for Snapshot Day website)
2What is Enterococci bacteria? A bacteria correlated with many of the human pathogens found in raw sewage.It replaced ‘fecal coliform’ as the federal standard for water quality in public beaches in brackish/estuarine waters.Enterococci strongly correlates with swimmer illness so it is useful for testing in areas where the water carries a ‘recreational use’ classification**It is a goal of the Hudson River Estuary Program Action Plan that much of the river will fall under this classification.
3What are Potential Sources of Sewage in the Hudson? Combined sewer outfalls* Malfunctioning wastewater treatment facilitiesMalfunctioning septic tanksRunoff from streets and banks of waterwaysWaste from boats and swimmers* where sewage and storm drains are connected - as in NYC and - rainfall can cause the system to overload, bypassing the treatment facility
5CSO Facts for New York City 70% of NYC’s sewers are combinedMore than 494 outfalls in NYCOverflow can occur with 1/10th inch of rainfall due to all the pavement and other impervious surfaces!• Individual outfalls release sewage times per year• 27 billion gallons/year is released in NYCTake a look at a ruler and see what a little amount of rain 1/10th inch is!That equates to once every 4.5 to 7 days, or the equivalent of one to two times a week!
6Piermont Pier in Rockland County In this study Enterococci is studied as indicators of raw sewage in the Hudson River focusing on two locationsPiermont Pier in Rockland County125th street in West Harlem
8Piermont Pier Suzanne collecting a water sample Population (2000 Census): 2,607Popular location for fishing, crabbingSparkill Creek drains 11.1 square miles of watershed. (http://nynjctbotany.org/whudson/nypiermont.html)Pier extends 1 mile into the river, built in 1841 as terminus of Erie RRPiermont Marsh is designated HRES site, rare birds are common
9Tested using EPA Method 1600, which does not distinguish sources of the bacteria, only presence & rate of presenceThe EPA standard for a single sample maximum is 104 Colony Forming Units (104) per 100ml of sample water.Presence - shows entero colonies to be countedAbsence - Clean agar plate with no growth
10EPA Method 1600: Membrane Filtration The ProcedureCollect samplesDilute samplesFilter diluted samplesIncubate on mEI agar platesCount colony growth
11Filtration Incubation at 41°C Colony Count (As viewed through a microscope)
12West Harlem Results Enterococci concentration reported as Colony Forming Units (CFU) forming per 100 ml - charted with Rainfall eventsX axis represents dates June-Aug 2007Look at this graph - Do you see a correlation between Enterococci (ENT) concentrations & rainfall? How often do ENT counts go higher than 104 CFUs/000ml?
15Piermont Sampling Sites Second Site - Piermont Pier - sampled in 2 places in Sparkill Creek and 3 spots around the pierPiermont Sampling SitesNorth Side of PierEnd of PierSouth Side of PierSparkill Creek: Below DamSparkill Creek: Above Dam
16Piermont: Enterococci and Rainfall for a 2 week period July 16-30th If you are comparing this graph to the Harlem River Site graph be careful to note that the Y axis here is in much lower increments, so overall rates of entero would be lower for this site.Rainfall does not seem to be a main source of enterococci in the Sparkill - there is a consistent loading from another source…let’s see if we can tell what might be a contributor…
17Piermont: North and South of Pier NorthSouth6/25/20072.51357/2/20072077.57/9/200732.515007/18/20071504457/24/200710630*geo mean19338Here is the data from sampling both sides of the pier. It seems the south side has a regular contribution.P-value= .007P-value <.05*See next slide for discussion of geometric mean
18Geometric mean & water quality Many wastewater dischargers, or regulators who monitor swimming beaches and shellfish areas, must test for and report bacteria concentrations. Often, the data must be summarized as a "geometric mean" (a type of average) of all the test results obtained during a reporting period.WHY? A geometric mean, unlike an arithmetic mean, tends to reduce the effect of very high or low values, which might bias the mean if a straight average (arithmetic mean) were calculated. This is helpful when analyzing bacteria concentrations, because levels may vary anywhere from 10 to 10,000 fold over a given period. In our sample on the previous page the range was from 10 to 1500, still a large span.Very generally the geometric mean is really a log-transformation of data to enable meaningful statistical evaluations. Practical definition: The average of the logarithmic values of a data set, converted back to a base 10 number.
19North Side South Side Outfall Pipe On the South side of the pier is the Sparkill Creek and an outfall pipe. Look at the next slides to see if you can tell how much each might have contributed to the ENT counts.Outfall Pipe
20Sparkill Creek P-value= .18 SparkillSparkill UP7/2/20071904107/9/20073155757/18/200715007/24/2007geo mean606853P-value= .18Both the upper & lower Sparkill sites seem to be regular contributors
21Outfall and Mid-Channel Comparison 9/26/200613.0210/18/20061500.011/10/2006350.04/18/2007624.02724/25/20071500102.55/21/2007220.056/18/200725.06/20/20072.57/12/200712.57/16/20078/23/2007324geo mean82.39.8P-value= .055Sampling at the outfall varies considerably with just over half the samples exceeding standards.Piermont Outfall (from boat)Tappan Zee Mid-channel
22Mid-Channel sampling site from boat Tappan Zee BridgeMid-Channel sampling site from boatPiermont PierOutfall sampling site from boatCould you argue that the Sparkill Creek also contributes to the Outfall sampling site? Would the tidal cycle at sampling time have any impact on contributions found from the Sparkill or the Outfall?
23Previous Studies have considered other items like: Salinity - found salinity negatively correlates with ENTGrazing Communities - will affect bacteria mortality & inactivityUV light - affects bacteria mortality & inactivitySediment - Like many other contaminants, bacteria can be retained & resuspended in sediments. Tidal resuspension of sediments is a factor to consider.
24Conclusions Rainfall strongly correlates with ENT concentrations Tidal action may influence persistence of ENT or disturb sediment and resuspendSome wastewater treatment plants are not up-to-date with effective treatment processesThere is a need for holistic approaches, ecologically sound practices such as those suggested in the following slides…
25Current CSO Legislation - legislation attempts to control the problem through laws/legal remedies Clean Water Act - enacted 1977EPA CSO Control PolicyLong Term Control Plans (submitted 6/30/07)Tank constructionFloatables controlsWet weather capacity upgradesSewer system improvementsNo discussion of BMPs (best management practices) to reduce stormwater volume
26We need to switch from thinking of stormwater as a WASTE to be treated (costing the city more money and energy) to looking at it as a RESOURCE to be used.Yes, capturing more stormwater so that less volume actually reaches the rivers or sewers and treatment plants
27One small way - encouraging Green Roofs/Rooftop Gardens Capture and absorb stormwaterCreate wildlife habitatCounteract “urban heat island” effectAesthetic benefitsCosts ~$8-10/sq.ft. more than reg.
28Incentives Chicago leads U.S. in sq.ft. of green roofs first municipal green roof in country atop city hallProvides grants and stormwater “credits”Density bonus in central business districtExpedited permit process, fee waivers
29PLANYCIn 2007, property tax abatement to offset 35% of the installation cost of green roofs
30What Other Ideas Can you Think Of? 1.More street trees2.Rain barrels3.4.5.
31Suzanne’s research was supported with help from: Peter Bower Greg O’Mullan Sarah McGrath John Lipscomb and Riverkeeper Lamont Doherty Earth Observatory Hudson River Foundation Natural Resources Defense Council