“E. coli, Enterococci and Protozoan Transport in New Mexico Watersheds”
G. M.
1
Huey
& Meyer, M.
New Mexico Environment Department – Santa Fe, NM
New Mexico Highlands University - Las Vegas, NM
Research funded by the National Institutes of Health - MBRS
Introduction:
The montane-forested (ponderosa pine and mixed conifer) Gallinas watershed (21,800 ha)
provides 95% of the municipal water for the City of Las Vegas, NM (population 16,500).
The area is listed among the New Mexico State Forestry’s twenty most vulnerable urban
interface communities for wildfire outbreak. In May/June 2000 the catastrophic Viveash Fire
burned the montane (ponderosa pine and mixed conifer) Cow Creek watershed (10,100
ha) that is contiguous to the Gallinas watershed. Runoff from the watershed through the
summer after the fire was highly degraded with suspended solids and associated
pollutants. This caused great concern for the water supply of Las Vegas. This study was
initiated to predict potential risk to the city of Las Vegas’s water supply based on
information from the burned Cow Creek watershed. Monitoring sites were also established
on the Gallinas River below the City of Las Vegas, NM and in a prairie rangeland
watershed. This poster presents the results from the burned Cow Creek (CC) watershed,
the unburned Gallinas watershed with the monitoring site on the Gallinas River near
Montezuma, NM (MZ), the prairie rangeland watershed in the Spring Arroyo (SA) and the
urban/commercial City of Las Vegas, NM with the monitoring site downstream from city
runoff on the lower Gallinas River (LG) (effective runoff area: 3,800 ha).
In addition, funds were provided by the NM Water Resource Research Institute for a
bacterial source tracking (BST) project for the 2005 monitoring season. Each monitoring
site was sampled for E. coli source identification, based on DNA fingerprinting, to
determine whether sources were human or non-human.
Microbial Concentrations
Location of Study Area
Rio Grande R
Ecoli & Entero (counts/100ml)
Crypto & Giardia (counts/L)
10000
ABQ
Pecos R
USA
New Mexico
Entero
Crypto
1000
Giardia
100
10
1
Upper Pecos River Basin
Bacteria concentrations were highest from the LG watershed, slightly less at the SA &
MZ sites, and lowest at the CC site. Yields are also highest from the LG watershed;
however, due to increased discharge from the burned watershed, loads are similar between
the SA, MZ and CC sites. Cryptosporidium concentrations were highest at LG, less at SA,
lower at CC and least at MZ. Yields were also highest at LG and, due to flow conditions,
similar at SA, CC and MZ. There was not sufficient positive analysis for Giardia at SA & CC
to perform flow adjusted concentrations ( <3). LG & MZ concentrations & yields were similar
to Cryptosporidium results.
0.1
San Miguel Co.
CC
•Establish potential pathogen indicators and risk to human health based on watershed
characteristics
SA
MZ
LG
Microbial Yield
LG
•Forecast potential risk to the city of Las Vegas’s water supply (Gallinas River) based on
information from the burned Cow Creek watershed
1.00E+12
Gallinas R.
CC
MZ
1.00E+10
Runoff caused by storm events from montane watershed areas that have been recently
impacted by forest fires has elevated levels of suspended solids & high turbidity relative to
unimpacted watersheds.
Burned watersheds pose a higher risk to human health due to increased pathogen
concentrations & numeric transport loads relative to unimpacted watersheds.
1.00E+09
Microbial Yield
(counts/ha)
Pecos R.
Upper Pecos River Basin with monitoring sites: Cow Cr. (CC) (burned); Gallinas R. near
Montezuma (MZ) (unburned); and Lower Gallinas R. (LG) (urban/commercial). Scale: 204
km (127 mi)) from the left to right edge of the illustration.
Methods:
 Event activated monitoring stations measure & record stream flow in 15-minute
Spearman Rank Correlations for E. coli and Enterococci against TSS, NTU and
discharge (CFS) are variable. The CC site did not significantly correlate for any of the
variables. The SA site showed the greatest amount of significant correlations, with both
types of bacteria correlating with turbidity and E. coli correlating with discharge. The MZ site
showed a correlation between E. coli for both TSS and turbidity, while the LG site showed a
correlation between Enterococci and turbidity. Few P-values for Cryptosporidium and
Giardia data with TSS, NTU and CFS from the four monitoring sites proved significant due
to the low number of positive values. However, Giardia did correlate significantly with
discharge at the SA site and with total suspended solids at the MZ site.
Ecoli
Entero
Crypto
Giardia
1.00E+11
Hypothesis:
1.00E+08
1.00E+07
1.00E+06
1.00E+05
1.00E+04
1.00E+03
Stream Hydrology (CFS)
Conclusion:
1.00E+02
1.00E+01
Mean
Cow Creek Spring
Arroyo
Montezuma
8.82
23.67
1.64
Lower
Gallinas
1.00E+00
CC
6.51
Median
5.03
0.00
6.18
1.53
SE Mean
0.48
0.49
0.94
1.43
Minimum
0.6
0.00
2.22
0.07
Maximum
80.65
1395.60
741.00
812.32
Stream
CC (burned)
SA (Prairie)
TSS Concentration, Turbidity & TSS Yield
LG (urban/
Commercial)
TSS Concentration, Turbidity and TSS Yield
10000.00
10000.00
TSS (mg/L)
TRB (NTU)
TSS Yield (kg/ha)
10.00
10.00
1.00
1.00
0.10
CC
SA
MZ
LG
TSS Yield (kg/ha)
1000.00
100.00
MZ
LG
Microbe
E. coli
Enterococci
Cryptosporidium
Giardia
TSS vs. TRB
E. coli
Enterococci
Cryptosporidium
Giardia
TSS vs. TRB
E. coli
Enterococci
Cryptosporidium
Giardia
TSS vs. TRB
E. coli
Enterococci
Cryptosporidium
Giardia
TSS vs. TRB
TSS
0.0609
0.1525
0.3635
0.2754
0.2367
0.1154
0.4435
0.1542
0.0097
0.1205
0.6595
0.0036
0.1071
0.0029
0.5216
0.7757
TRB
0.2830
0.1161
0.5272
0.2193
<0.0001
0.0373
0.0036
0.5730
0.2463
0.0100
0.0376
0.0645
0.4042
0.4042
0.0042
0.1768
0.0100
0.2488
0.9129
<0.0001
CFS
0.2015
0.8205
0.6365
0.8640
0.0458
0.8173
0.5135
0.0280
0.1979
0.1387
0.4042
0.4492
0.0509
0.0666
0.9477
0.9129
E. Coli Source Tracking – DNA Analysis
1000.00
100.00
SA
Spearman Rank P-values
MZ
(unburned)
TSS (mg/L) & TRB (NTU)
Methods for the Examination of Water and Wastewater, 20th Edition
2Colilert and Enterolert from IDEXX
3EPA Method 1621
4FLUX, U.S. Army Corps of Engineers by William Walker
The urban watershed (LG) generated the greatest turbidity values (NTU) and TSS
concentrations, with mean values of 2,147 NTU and 3,988 mg/L, respectively. When paired
with discharge, LG also produced the highest yield at 3,249 kg/ha. The prairie watershed
also generated high NTU & TSS values but produced a lower yield due to low flow values
from the intermittent arroyo. Values were significantly lower at the montane sites. The
burned watershed (CC) produced a lower turbidity than the forested watershed (MZ), 25.8
NTU and 91.3 NTU, respectively, but generated higher TSS concentrations (80.3 mg/L vs.
13.4 mg/L, respectively) and subsequently higher yield 19.6 kg/ha vs. 0.8 kg/ha. This
inverse relationship between TSS & NTUs found between the MZ & CC watersheds may be
due to minerals eroded from the burned area in contrast to reflective organic materials of
less density in the forested watershed. For each site, NTU & TSS were significantly
correlated to each other with a P-value of < 0.01.
Ecoli
Study
Area
Santa Fe
•Quantify Escherichia coli, Enterococci spp., Cryptosporidium spp. and Giardia lamblia
concentrations and transport in runoff from four ecologically diverse watersheds in northern
New Mexico
1Standard
Summary of Results and Discussion:
100000
Objectives:
intervals.
 Collected automated composite samples from rising & falling hydrographs during storm
runoff events in the summer and fall 2003 & 2004.
Collected biweekly grab samples during base flow conditions.
 Quantified total suspended solids1 (TSS), turbidity1 (TRB), E. coli2, Enterococci2,
Cryptosporidium3 and Giardia3 in water samples.
Data Analysis and statistical calculations with FLUX4 for flow weighted
concentrations and loading for yield determination.
Bacteria Source Tracking contracted through Source Molecular, Inc; Gainesville, Fla.
2
L
Cow
Creek
(CC)
Sample Size
Non-Human
Indeterminate
Human
<6
n/a
n/a
n/a
Spring
Arroyo
(SA)
10
10
0
0
Montezuma
(MZ)
20
20
0
0
Lower
Gallinas
(LG)
29
25
3
1
1.Urban/commercial areas produce very high concentrations of TSS, TRB and
microbial contamination during storm runoff events. The LG watershed had TSS
and TRB concentrations and/or yields that were two to three orders of magnitude
greater than a burned forested watershed (CC) and an unburned forested
watershed (MZ). Fecal contamination from human sources may be of concern in
urban areas during storm runoff events.
2.The burned CC watershed had greater TSS concentrations and yields than MZ, but
the forested MZ watershed produced greater microbial concentrations. This may
be due to increased proximity of livestock & wildlife to the riparian zone. Microbial
loading was similar for the two watersheds due to increased runoff from the CC
watershed.
3.Ephemeral arroyos from rangeland drainages may contain elevated concentrations
of TSS, TRB and microbial contamination during storm runoff events. However,
due to the intermittent nature of these drainages, long term loading effects are not
as great as these concentrations suggest.
3.Municipal water supply systems are vulnerable to higher TSS and TRB
contamination from burned forests, especially during runoff events.
4.Turbidity can be used as an indicator of E. coli in surface waters, but it has not been
shown as an effective indicator of Enterococci, Cryptosporidium and Giardia.