NYC DEP Bureau of Water Supply, Water Quality Division of Science and Research Giardia and Cryptosporidium Monitoring in the New York City Watershed A Retrospective Kerri Alderisio Watershed Science and Technical Conference September 17, 2008 West Point,
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NYC DEP Bureau of Water Supply, Water Quality Division of Science and Research Giardia and Cryptosporidium Monitoring in the New York City Watershed A.
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NYC DEP Bureau of Water Supply, Water Quality
Division of Science and Research
Giardia and Cryptosporidium Monitoring in the New York City Watershed
A Retrospective
Kerri Alderisio
Watershed Science and Technical ConferenceSeptember 17, 2008 West Point, N.Y.
“The Conference will bring scientists, engineers and technical experts together with watershed stakeholders and the public, to technically inform and present leading-edge research findings on information collected to date, with regard to the protection of the nation’s largest unfiltered surface water supply.”
- 2008 WSTC brochure
Outline
Are they out there? Method History
If so, how many? Data Review
Are there any trends? Giardia
Are they harmful to people? Additional Research
Are they out there?
• An accurate, reproducible, validated, approved method is paramount to answering this question…
• Methods for protozoan recovery have undergone many changes over the past 20 years…
DEP Protozoan Method History(16 years; 3 methods; 3 laboratories)
Years Methods Details Laboratory
1992 – 1999(lowest recovery)
ASTM
1000L
Spiral wound nom. Filter, PSF, well
slide
NYS DOH
/ ECWA
1999 – Oct 2001
(20-30% recovery)
ICR
100L
Spiral wound nom. Filter, PSF, Hoef.
man., filter on slides
NYC DEP
Oct 2001-2008(50-75% recovery)
1623HV
50L
Envirochek abs. filter, IMS, spot on
slides
NYC DEP
Method 1623 – Collection & Analysis
IMS Technology
Other Method Improvements:Pressure and NaHex Experimental Results
Data
Type>50psi25psi10psi
Without NaHexNaHexWithout NaHexNaHexWithout NaHexNaHex
80
70
60
50
40
30
20
10
0
Boxplot of 10psi, 25psi, >50psi vs Type
56%
18%
45%
12%
39%
1%
n=8
Stain Experiment
01/01/200201/01/2003
01/01/200412/31/2004
12/31/200512/31/2006
Date
0
1
2
3
4
5
6
7
8
9
10
11
12
Cysts
/50L
Fit = 0.1 LOWESS Smooth
Easy
Stain
Avg. Giardia/ 50L
Merifluor EasyStain
Giardia Detection
2.85 1.06
82% 45%
Stain Differentiation Results• P. Wallis, Hyperion
G. murisSame lot #
G. intestinalis
Colorseed Experiment (FITC & TR)
Damaged cysts
Faded FITC
Subjective Texas Red
Recovery Comparison DEP 1623 and DEP ColorSeed Method
Giardia Recovery Using WI Spike and ColorSeed Spike in DI waterNYC DEP Pathogen Laboratory, Method 1623
0
10
20
30
40
50
60
70
80
1 2 3 4 5 6 7 8 9 10 11 12 13
trial
% re
cove
ry
WI
CS
avg 58%
avg 37%
Giardia Recovery Using Method 1623: Wisconsin spike with 1623 buffer (50L) and ColorSeed with DEP Buffer (40+10L)