“E. coli, Enterococci and Protozoan Transport in New Mexico Watersheds”

1. Cow Creek Spring Arroyo Montezuma Lower Gallinas Mean 8.82 1.64 23.67 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 “E. coli,Enterococci and Protozoan Transport in New Mexico Watersheds” G. M. Huey1 & Meyer, M. L2New 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 Summary of Results and Discussion: 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. 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. 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. • Objectives: • Quantify Escherichia coli, Enterococci spp., Cryptosporidium spp. and Giardia lamblia concentrations and transport in runoff from four ecologically diverse watersheds in northern New Mexico • Establish potential pathogen indicators and risk to human health based on watershed characteristics • Forecast potential risk to the city of Las Vegas’s water supply (Gallinas River) based on information from the burned Cow Creek watershed Microbial Yield • Hypothesis: • 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. • Methods: • Event activated monitoring stations measure & record stream flow in 15-minute 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. • 1Standard 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 Conclusion: 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. Stream Hydrology (CFS) Spearman Rank P-values TSS Concentration, Turbidity & TSS Yield E. Coli Source Tracking – DNA Analysis