Mohawk River Water Quality: Risk Evaluation of Combined Sewer Overflow and Runoff Events

C. Rodak1, X. Wei1, J. Schneider2

1 Civil Engineering, SUNY Polytechnic Institute, Utica, NY 2 OCM BOCES, Seven Valleys New Tech Academy, 240 Port Watson St, Cortland NY

Abstract During the Summer of 2016 nine locations along the Mohawk River in the Utica-Rome area were sampled for general water quality parameters and microbial indicators of fecal contaminations (E. coli and enterococci). When compared to the 2012 RWQC, microbial counts frequently exceeded the beach action value thresholds at sample locations in Utica, NY while violations in the Rome tailwater were less common. Microbial counts correlated well with rain events, demonstrating elevated microbial counts following rain events at sampling locations directly downstream of known CSO locations. At one sampling location in Utica, extremely high microbial counts were ultimately attributed to a broken sewer pipe which also appears to have impacted the water quality of other sample locations up 3.5 miles downstream. These microbial counts decreased significantly once the leaking pipe was identified and repaired on July 29th 2016. The performance indicators of reliability, resilience, and vulnerability were explored as a quantitative metric for communication of the frequency, duration, and severity of contamination events. Sampling locations in Rome had high reliability and resilience indicating infrequent, short-term elevated microbial counts compared to those in Utica which had frequent, long-term, contamination events well above the recreational thresholds. Three Summary Points of Interest

• Bacterial indicator counts downstream of known CSO locations demonstrated greater increases in counts following intense rain events

• Elevated bacterial counts at several locations were tied to a previously unknown leaking sewer pipe

• Exploration of performance indicators identified differences in the frequency, duration, and severity of microbial contamination between samples from Rome and Utica.

Keywords: E. coli, enterococci, water quality, Mohawk River, performance indicators, Combined sewer overflow (CSO)

NEW YORK STATE WATER RESOURCES INSTITUTE

Department of Biological and Environmental Engineering 230 Riley-Robb Hall, Cornell University Tel: (607) 254-7163 Ithaca, NY 14853-5701 Fax: (607) 255-4449 http://wri.cals.cornell.edu Email: nyswri@cornell.edu

Mohawk River Water Quality: Risk Evaluation of Combined Sewer Overflow and Runoff Events

This report was prepared for the New York State Water Resources Institute (WRI) and the Hudson River Estuary program of the New York State Department of Environmental Conservation, with support from the NYS Environmental Protection Fund

Introduction The Mohawk River supplies drinking water to several communities in upstate New York and provides a source of recreational activities throughout the region1. Sampling campaigns of the Mohawk River have documented issues with biological and chemical contaminants from combined sewer overflow (CSO) events and urban and agricultural runoff. Nitrates, dissolved oxygen, and pH are a few of the important chemical parameters which are of concern in the Mohawk River2 while E. coli and enterococci, both indicators of fecal contamination, are also present in the Mohawk River. Over the past 5 years, samples analyzed for these microbial indicators along the Mohawk River have exceeded acceptable levels as defined by the EPA resulting in drinking water quality concerns and recreational limitations and closures. The goal of this project was to expand on the current sampling approaches by pursuing high-frequency baseline monitoring in the Utica-Rome area in hope to draw useful correlations between the sources of contamination (stormwater runoff, sewer overflow, etc.), rainfall events, and the resulting water quality issues. Methods Nine geographical locations in the Utica-Rome area were selected to serve as sampling points during the summer of 2016 (Figure 1). Six of the sampling locations are along the Mohawk River in Utica, NY and three locations are along the Delta Reservoir tailwater in Rome, NY. The six locations in Utica were chosen upstream and downstream of 3 known CSOs and the three locations in Rome were chosen to show the progression of water quality through Rome starting from the fairly pristine Delta Reservoir. There are no known CSOs in Rome, NY. The direction of flow for these samples starts at the Delta Reservoir (TW1), travels through Rome (TW2 and TW3), through the western sample location in Utica (WS1) where it is then joined with water from Sauquoit Creek (SQ1) and then travels east through Utica (WU1 and WU2) past the wastewater treatment plant (WW1 and WW2)

Over a two-month period during the summer of 2016, approximately 23 grab-samples were collected at each of the 9 locations, at varying collection intervals spanning 2 weeks to 1 day. The number of days between trips was neither scheduled or random as we intentionally targeted large rainfall events when possible. Overall, 62.5% of the samples were collected within 48hrs of each other and no samples were collected between July 2nd -18th of 2016. At each sample location, we collected data on pH, DO, Temperature, Conductivity, Nitrates, TOC, E. coli and enterococci. In the field, we used a HACH Sension+ MM156 Multimeter to measure in-situ pH, DO, Temperature, and Conductivity. For the other parameters, a grab sample was collected and brought back to the lab. These samples were analyzed for Nitrates, TOC, E. coli and Enterococci via HACH HR Cadmium reduction, UV245 adsorption, IDEXX Colilert and IDEXX Enterolert methods respectively. Initial E. coli and enterococci tests revealed bacterial counts outside of the MPN range of our tests when collected after rain events and therefore undiluted and diluted samples were analyzed to ensure proper quantification of the higher microbial counts. The diluted sample values were only used in the analysis when the undiluted samples reached the MPN limits of our tests. To test for cross contamination during the collection and transportation of the samples, blanks were brought

Figure 1: Map of sampling locations in Utica and Rome NY.

Mohawk River Water Quality: Risk Evaluation of Combined Sewer Overflow and Runoff Events

This report was prepared for the New York State Water Resources Institute (WRI) and the Hudson River Estuary program of the New York State Department of Environmental Conservation, with support from the NYS Environmental Protection Fund

into the field. In addition, samples with a known microbial concentration range were used to verify laboratory procedures. Results & Discussion The content below focuses on the results of this study pertaining to the microbial indicators. A deeper analysis of all water quality parameters is on-going. Recreational Water Quality Criteria First, the microbial indicators were compared to the EPA recommended 2012 recreational water quality criteria3 (RWQC) specifically comparing the data to the 30-day geometric mean, 90th percentile, and beach action values. Due in part to intentional sampling after storms and an unforeseen broken sewage pipe along the sample path, all six of the Utica sites exceeded the 30-day geometric mean (GM) and the 90th percentile statistical threshold value (STV) for E. coli and enterococci. Along the Delta reservoir tailwater in Rome, all samples passed the GM and STV for E. coli but failed to pass the enterococci GM and STV. Therefore, the data set results in different conclusions about the water quality based on the microbial indicator. Single samples were also compared to the beach action values (BAV) recommended by the EPA: 235cfu/100mL and 70 cfu/100mL for E. coli and enterococci respectively3. Similarly, to the other recommended thresholds, there is also a discrepancy between the occurrence of enterococci and E. coli BAV violations (Table 1). Overall, sample locations in Rome exceeded the BAV threshold less frequently than those in Utica. For a summary of general statistics of the microbial indicators at each location see the appendix.

Table 1: % samples below Beach Action Value

Sample ID* E. coli BAV enterococci BAV

235 cfu/100mL 70 cfu/100mL

TW1 100% 65%

TW2 96% 48%

TW3 87% 26%

WS1 10% 0%

SQ2 13% 0%

WU1 8% 0%

WU2 9% 0%

WW1 30% 21%

WW2 33% 13%

* Samples listed in the general direction of flow

Temporal trends with location, rainfall, and CSO release E. coli and enterococci counts in Rome, NY generally increased as the water moved through the city and have a weak correlation to rainfall events. However, bacterial counts from the Mohawk River samples did not demonstrate a clear spatial pattern in the microbial counts. Some locations increased dramatically following rainfall events, as seen in Figure 2. Three intense rainfall events during the sampling period were connected with CSO releases, the most notable of which occurred between the WW1 and WW2 sampling locations. These two locations were intentionally placed upstream and downstream of an identified and monitored CSO near the local wastewater treatment plant providing the most compelling evidence between bacterial counts, CSO events, and rainfall.

Figure 2: E. coli concentration from July 19th -August 18th for sample locations WW1 WW2 and SQ2 in Utica, and TW1, TW2 and TW3 in Rome. The boxes indicate the duration of rainfall and are labeled with the total depth of rain for the event.

Broken Sewer Pipe On July 29th 2016, the Observer Dispatch reported the discovery of a broken sewer pipe in the Mohawk river between the 1-90 toll road and Mohawk Ave; this location was less than 2,000ft upstream of one of our sampling locations, WS14. Very high microbial counts for both bacteria types were recorded at this location but where unexplained at the time. The concentration of E. coli and enterococci decreased with increasing distance from WS1 and ultimately the source of contamination (Figure 3). Importantly, the abnormally

Mohawk River Water Quality: Risk Evaluation of Combined Sewer Overflow and Runoff Events

This report was prepared for the New York State Water Resources Institute (WRI) and the Hudson River Estuary program of the New York State Department of Environmental Conservation, with support from the NYS Environmental Protection Fund

high microbial concentrations decreased to approximate background levels following repair of the pipe on July 29th 20165. After July 29th, small increases in bacterial counts for the previously impacted sample locations WS1, WU1, and WU2 were also observed on days following the three storm events identified in the previous section.

Figure 3: E. coli concentrations at WS1, WU1, and WU2 downstream from a leaking sewer pipe. Bacterial counts dropped following the repair of the pipe on July 29th 2016. The sample location furthest from the pipe, WW2, is included on the graph for reference.

Reliability, Resilience, and Vulnerability Using the beach action value as a threshold, performance indicators based on the microbial indicators for the Mohawk River were explored. Here we investigated the use of reliability, resilience, and vulnerability (RRV) indicators6. Previous water quality-based applications of RRV have focused on the evaluation of dissolved oxygen levels, sediments, nutrients, and other constituents under current conditions7, potential management decisions8, and meteorological changes due to climate change9,10. As applied here, reliability (𝛼), represents the likelihood that E. coli concentrations are below 235 cfu/100mL represented mathematically as:

𝛼 = 𝑃[𝐶𝐸𝑐𝑜𝑙𝑖(𝑛) < 𝐵𝐴𝑉𝐸𝑐𝑜𝑙𝑖] Eq. 1 Similarly, resilience (γ), represents the likelihood that the next sample from the Mohawk river will produce an E. coli concentration below the BAV given the current sample concentration is above the BAV:

𝛾 = 𝑃[𝐶𝐸𝑐𝑜𝑙𝑖(𝑛 + 1) < 𝐵𝐴𝑉𝐸𝑐𝑜𝑙𝑖|𝐶𝐸𝑐𝑜𝑙𝑖(𝑛) ≥ 𝐵𝐴𝑉𝐸𝑐𝑜𝑙𝑖] Eq.2 Lastly, vulnerability (ν), describes the average exceedance of the BAV threshold:

𝜈 =1

N∑(𝐶𝐸𝑐𝑜𝑙𝑖(n) −𝐵𝐴𝑉𝐸𝑐𝑜𝑙𝑖)

Eq.3 Using these indicators, we determined the frequency, duration and severity of E. coli counts at our 9 sampling locations (Table 2).

Table 2: RRV performance Indicator results for E. coli

Sample ID Reliability Resilience Vulnerability

TW1 1.00 Undefined Undefined

TW2 0.96 1.00 109.1

TW3 0.87 1.00 159.9

WS1 0.15 0.12 9972.7

SQ2* 0.13 0.20 831.6

WU1 0.08 0.14 4651.7

WU2 0.09 0.14 3103.4

WW1 0.29 0.35 940.6

WW2 0.33 0.31 3609.1

*SQ2 is a tributary into the Mohawk River

Based on the RRV results, samples collected in Rome behaved quite differently than samples collected in Utica (additional analysis on-going). Of all the sampling locations, the portion of the Mohawk river impacted by the sewer leak had the lowest reliability and resilience and high vulnerability. This means the samples were likely to exceed the BAV, remain above the BAV on the next sample if the current sample was already above, and on average the samples exceeded the BAV by 1,000-10,000 cfu/100mL depending on location. Conversely, the samples taken in Rome rarely exceeded the BAV but when they did, on average the samples exceeded the BAV by 100-150 cfu/100mL and the next sample was always below the BAV demonstrating high resilience for the sampling area and water body in Rome. Policy Implications One of the goals of this work was to identify information which can be gained from high frequency

Mohawk River Water Quality: Risk Evaluation of Combined Sewer Overflow and Runoff Events

This report was prepared for the New York State Water Resources Institute (WRI) and the Hudson River Estuary program of the New York State Department of Environmental Conservation, with support from the NYS Environmental Protection Fund

sampling. While this data set is still limited, the high sampling data did demonstrate responses to intense rain events and a leaking sewer pipe suggesting more data could help uncover correlations between microbial concentrations, rain events, sources of contamination. It also allowed us to explore performance indicators, such as RRV, which could be used to make regulatory decisions. For example, based on the RRV results for the data in Rome, one sample above a BAV may not represent a great concern as the probability of recovery (resilience) is high. However, a sample above the BAV in Utica is much less likely to recover by the next sample indicating a longer period of elevated microbial concentrations for the sampled location. Outreach Comments No direct outreach was conducted. However, contact was made with Riverkeeper and SUNY Cobleskill researchers conducting community-driven science on water quality in the Mohawk River. A session for recruiting volunteers for the Riverkeeper/SUNY Cobleskill project in the Utica/Rome area was held on the SUNY Poly campus on April 10th. Dr. Rodak and her 2017 summer interns will also be helping with their sampling over the summer. Student Training One student was officially hired for this project but two students shared time between this project and another environmental engineering project during the summer of 2016. Stephen Nguyen is a current student in Civil Engineering and was a rising junior during the summer of 2016. Robyn Christoferson is a 2016 SUNY Poly graduate in Biology. Both students were trained in basic laboratory safety, water sampling techniques, the collection of basic water quality parameters, and data analysis. References 1. Mohawk River Watershed Management Plan.

Mohawk River Watershed Coalition and New York State Department of State, March 2015. URL: http://mohawkriver.org/wp-content/uploads/2015/03/MohawkWatershedMgmtPlan_Mar2015_Final_r.pdf

2. Upper Mohawk River Coliform Bacteria Monitoring Project: Portions 12 and 13 in Utica-Rome Area. New York State Department of Environmental Conservation. November 2013 Revised January 2014. URL: http://www.dec.ny.gov/docs/water_pdf/mopath1714.pdf

3. Recreational Water Quality Criteria. Environmental Protection Agency Office of Water, 2012. 820-F-12-058. URL: https://www.epa.gov/sites/production/files/2015-10/documents/rwqc2012.pdf

4. What’s Leaking into the Mohawk River. Utica Observer-Dispatch, July 29th 2016. URL: http://www.uticaod.com/news/20160729/whats-leaking-into-mohawk-river

5. Pipe that spurted sewage into Mohawk River fixed. Utica Observer-Dispatch, July 29th 2016. URL: http://www.uticaod.com/news/20160729/pipe-that-spurted-sewage-into-mohawk-river-fixed

6. Hashimoto, T., Stedinger, J., & Loucks, D. (1982). Reliability, resiliency, and vulnerability criteria for water-resource system performance evaluation. Water Resources Research, 18(1), 14-20. doi: 10.1029/WR018i001p00014

7. Hoque, Y., Tripathi, S., Hantush, M., Govindaraju, R (2012) Watershed reliability, resilience, and vulnerability analysis under uncertainty using water quality data. Journal of Environmental Management 109 (2012) 101-112.

8. Sarang, A., Vahedi, A., & Shamsai, A. (2008). How to quantify sustainable development: A risk-based approach to water quality management. Environmental Management, 41(2), 200-220. doi: 10.1007/s00267-007-9047-5

9. Fowler, H., Kilsby, C., & O'Connell, P. (2003). Modeling the impacts of climatic change and variability on the reliability, resilience, and vulnerability of a water resource system. Water Resources Research, 39(8), 1222. doi: 10.1029/2002WR001778

10. Asefa, T., Clayton, J., Adams, A., and D. Anderson (2014) Performance evaluation of a water resources system under varying climatic conditions: Reliability, Resilience, Vulnerability and beyond. Journal of Hydrology, 508 (2014) 53-65

Mohawk River Water Quality: Risk Evaluation of Combined Sewer Overflow and Runoff Events

This report was prepared for the New York State Water Resources Institute (WRI) and the Hudson River Estuary program of the New York State Department of Environmental Conservation, with support from the NYS Environmental Protection Fund

Appendices

Table A: General Statistics for bacterial indicators

E. coli concentration (cfu/100mL) enterococci concentration (cfu/100mL)

Sample ID* Min Max GM 90th Min Max GM 90th

TW1 33.9 135.4 66.4 115.1 24.6 920.8 84.8 610.4

TW2 19.9 344.1 58.3 112.0 19.7 613.1 93.9 378.4

TW3 22.3 579.4 77.7 237.6 16.8 1413.6 145.2 501.0

WS1 84.0 24196.0 2873.1 17329.0 125.4 4839.2 1501.2 4839.2

SQ2** 140.1 2419.6 671.7 2419.6 135.4 2419.6 1156.3 2419.6

WU1 121.0 14136.0 2179.9 11782.8 150.0 4839.2 1676.9 4839.2

WU2 224.7 12997.0 1756.8 7387.0 164.3 4839.2 1386.3 4564.5

WW1 31.0 4884.0 438.4 1986.3 21.1 4839.2 330.3 2321.4

WW2 31.0 24196.0 558.5 8183.8 29.1 5172.0 509.6 4839.2

* Samples are listed in general direction of flow

**SQ2 is a tributary into the Mohawk River