New directions in bacterial management for Grand Lake s swimming areas

Transcription

1 New directions in bacterial management for Grand Lake s swimming areas Richard M. Zamor Ecosystems and Lake Management Grand River Dam Authority

2 What are Fecal Indicator Bacteria (FIBs)? Escherichia coli and Enterococci Commensal bacteria inhabiting gastrointestinal tracts of many endothermic animals Pathogen indicators indicate presence of fecal contamination A substance that indicates the potential for human infectious disease Most strains of enterococci and E. coli do not cause human illness E. coli is rarely pathogenic Enterococci are among most common causes of nosocomial (originating in hospitals) infection

3 Problem: Beach Closing at Grand Lake State Park Reports of rash and gastrointestinal illness after Memorial Day weekend Found elevated levels of fecal indicator bacteria (FIBs) Beach closed June 3 rd November

4 FIB Assessment, Standards & Health Risk How do we assess FIB contamination? Membrane filtration Chromogenic substrate Genetic methods EPA and State Standards FIB One-time Sample (cfu ml -1 ) 5-sample geometric mean (cfu ml -1 ) E. coli Enterococci Associated Health Risk 36 out of 1000 swimmers negatively affected (gastroenteritis)

5 Grand Lake State Park FIB Sampling Sampled 3 sites (6/2 Pres.) Chromogenic Substrate Genetic Microbial Source tracking on 6/5 & 6/10 Sampled sediments on 7/7 MST again on 7/31 Sampled ephemeral creek Chromogenic substrate on 7/31 Sent tests from 8/12 to OKSDH to test for potential false positives Sampled algal mats on 8/18 8/20 BSP 1 BSP 3 BSP 2

6 MPN/100mL E. coli Enterococci Std BSP Elev Lake Elevation (ft) MPN/100mL sample Geometric Mean E. coli 5-sample Geometric Mean Enterococci Lake Elevation (ft) 0 740

7 Grand Lake State Park FIB Results Summary Chromogenic substrate E. coli disappeared by 6/20, Entero persisted until November Genetic Microbial Source tracking on 6/5 & 6/10 fecal contamination present but at detection limits Sampled sediments on 7/7 E. coli & Entero both detected MST again on 7/31 No sources identified Ephemeral Creek E. coli & Entero both detected, E. coli creek mouth Sent tests from 8/12 to OKSDH to test for potential false positives potential false positives found (Chromobacterium haemolyticum, Lactococcus garvieae, Enterococcus casseliflavus) Sampled algal mats on 8/18 8/20 No E. coli, high Entero

8 GRDA Bacteria Management Plan Objective To provide additional guidelines for body contact in the designated swimming areas and parks in cases where bacteria sources can be ascertained to further protect and assess risk to health and public safety Rationale for proposed guidelines Relationship between human health and FIBs from non-human and non-point sources is unclear New TSM from EPA for consideration for use in gathering information for development of alternative criteria or for better informing management decisions QMRA allows risk assessment of non-human sources Equivalent genetic WQS for Enterococci Method 1611 Retrospective look at 6/15 genetic MST Enterococci results were below this standard!

9 How do sources differ in their relative risk? Median Relative Risk 1 Enterococci E. coli (35 CFU/100mL) (126 CFU/100mL) 2012 RWQC health goal Source of fecal contamination Effluent Raw sewage Bovine Porcine Poultry (chicken) Waterfowl (gulls) Assumes direct deposition and that the prevalence of infection in each of the sources and the proportion of human-infectious pathogenic strains from is as reported in the literature (Soller et al., 2010, Table 2). Adapted from: Soller, J.A., Schoen, M.E., Bartrand, T., Ravenscroft, J., Wade, T.J Estimated human health risks from exposure to recreational waters impacted by human and non-human sources of faecal contamination. Water Research 44(16):

10 Water Sample for FIB Step 1. Initial Recommendation Above WQS for Geo. Mean or 90% OSCI At or below WQS for Geo. Mean (1 or more exceedances) or 75% OSCI Sample 90% OSCI At or below WQS for Geo. Mean (no exceedances) or 75% OSCI Step 2. Determine Possible Sources Microbial Source Tracking and Sanitary Survey Human Source Identified Nonhuman source identified 1 No source identified (potential for unknown source) Step 3. Risk Assessment & Recommendation Adjustment Quantitative Microbial Risk Assessment Resample for FIB FIB Above WQS; Check for non-obvious, non-point sources, & false positives Above WQS for Geo. Mean or 90% OSCI Above WQS equivalent risk (> 8 of 1000 for HCGI and/or >36 of 1000 for NGI) At or below WQS for Geo. Mean (1 or more exceedances) or 75% OSCI Sample 90% OSCI No sources identified, but at or above WQS w/no false positives. Risk not easily assessed or attributable. At or below WQS for Geo. Mean (no exceedances) or 75% OSCI. Below WQS equivalent risk (> 8 of 1000 for HCGI and/or >36 of 1000 for NGI) No sources identified, but at or above WQS w/false positives detected, FIB values decoupled from risk Step 4. Final Recomendation Red No primary body contact activity Yellow Information and education materials available to users for risk communication Green Unrestricted access 1 Examples of current possible genetic markers for use in genetic MST: human, general ruminant, general avian, cow, chicken, horse, dog, pig, sheep, gull, Elk, Canada geese, E. coli, and Enterococcus.

11 Step 1. Initial Recommendation Water Sample for FIB Above WQS for Geo. Mean or 90% OSCI At or below WQS for Geo. Mean (1 or more exceedances) or 75% OSCI Sample 90% OSCI At or below WQS for Geo. Mean (no exceedances) or 75% OSCI

12 Step 2. Determine Possible Sources Microbial Source Tracking and Sanitary Survey Human Source Identified Nonhuman source identified No source identified (potential for unknown source)

13 Step 3. Risk Assessment & Recommendation Adjustment Quantitative Microbial Risk Assessment Resample for FIB FIB Above WQS; Check for non-obvious, nonpoint sources, & false positives Above WQS for Geo. Mean or 90% OSCI Above WQS equivalent risk (>8 of 1000 for HCGI and/or >36 of 1000 for NGI) At or below WQS for Geo. Mean (1 or more exceedances) or 75% OSCI Sample 90% OSCI) No sources identified, but at or above WQS w/no false positives. Risk not easily assessed or attributable. At or below WQS for Geo. Mean (no exceedances) or 75% OSCI. Below WQS equivalent risk (>8 of 1000 for HCGI and/or >36 of 1000 for NGI) No sources identified, but at or above WQS w/false positives detected, FIB values decoupled from risk

14 Step 4. Final Recommendation Red No primary body contact activity Yellow Information and education materials available to users for risk communication Green Unrestricted access

15 Water Sample for FIB Step 1. Initial Recommendation Above WQS for Geo. Mean or 90% OSCI At or below WQS for Geo. Mean (1 or more exceedances) or 75% OSCI Sample 90% OSCI At or below WQS for Geo. Mean (no exceedances) or 75% OSCI Step 2. Determine Possible Sources Microbial Source Tracking and Sanitary Survey Human Source Identified Nonhuman source identified 1 No source identified (potential for unknown source) Step 3. Risk Assessment & Recommendation Adjustment Quantitative Microbial Risk Assessment Resample for FIB FIB Above WQS; Check for non-obvious, non-point sources, & false positives Above WQS for Geo. Mean or 90% OSCI Above WQS equivalent risk (> 8 of 1000 for HCGI and/or >36 of 1000 for NGI) At or below WQS for Geo. Mean (1 or more exceedances) or 75% OSCI Sample 90% OSCI No sources identified, but at or above WQS w/no false positives. Risk not easily assessed or attributable. At or below WQS for Geo. Mean (no exceedances) or 75% OSCI. Below WQS equivalent risk (> 8 of 1000 for HCGI and/or >36 of 1000 for NGI) No sources identified, but at or above WQS w/false positives detected, FIB values decoupled from risk Step 4. Final Recomendation Red No primary body contact activity Yellow Information and education materials available to users for risk communication Green Unrestricted access 1 Examples of current possible genetic markers for use in genetic MST: human, general ruminant, general avian, cow, chicken, horse, dog, pig, sheep, gull, Elk, Canada geese, E. coli, and Enterococcus.

16 Future plans Developing in-house capability to do MST Recently acquired a droplet digital PCR machine Working with members of Southern California Coastal Water Research Project Working with Dr. s Yueming Lu and Paul Philp on using Sterol fingerprinting Continue to develop the ability to assess risk in any affected site in our watershed in the future Working and discussing future strategies with other OK agencies Working with OU on current 5-year plan to further research throughout the watershed

17 Questions?

18 Extras

19 3000 E. coli Enterococci ~17K ~14K ~4K ~10K Std BSP Elev MPN/100mL Geo Mean E. coli Geo Mean Enterococci Lake Elevation (ft)

20 Watershed Inputs & Challenges Poultry Feed Lots Waste-Water Treatment