Storm Event Water Quality Testing for E. coli in Streams Feeding Canandaigua Lake
CLWA volunteers, trained by Community Science Institute (CSI), Ithaca, NY collected samples from streams draining into Canandaigua Lake during 2021, 2022 and 2023. Samples were collected and kept cold on wet ice and delivered to the CSI lab to be tested for E. coli within 24 hours of collection. Various parameters were recorded at the time of testing and chain of title was provided. CSI is NY State certified to test both potable and non-potable water for E. coli.
The initial plan was to collect 6 samples from spring until fall after storm events in 2021, but most of the streams identified for testing were dry that summer except during large storm events and we were able to sample only 3 times, on March 23 (28 for Seneca Point), July 18 and October 21. We sampled again on August 24 in 2022 and on April 18 and June 13 in 2023. In addition, I have included in the spreadsheet of results from limited testing conducted on August 28 of 2020 prior to this grant-funded research. Those tests were taken to Lozier Environmental Consulting, in Rochester NY, also a NY State Certified lab for non-potable water testing for E. coli.
The location coordinates for testing sites are in the CSI database with our test results for this project.
Yates County- description of streams sampled
Attempts to sample a stream draining Bare Hill were not successful due to lack of any water in those streams on any sampling date.
The Vine Valley stream was sampled where it runs under Dinehart Road, about halfway between there and where it drains into the lake (on private property not near a road), at the mouth of the stream and at the public beach. Sites were chosen on this stream to catch samples directly from agricultural land, again as it was diluted by largely forested adjacent slopes and at the mouth of the lake after it drained residential property known to have problematic septic systems. The swim area was sampled to determine if E. coli contamination impacted areas used for public recreation.
The West River, Naples Creek and Grimes Glem were each sampled one time.
Ontario County- description of streams tested
The stream at Deep Run was sampled where it crosses Rt 364 and in the public beach within the roped off swim area in about knee-deep water. The swim area was not sampled when there were large flocks of geese in the water and at the outwash delta due to likely in lake contamination and on one occasion where the flow in the stream was so low the water at the stream mouth was largely backwashed by lake water.
The Gage Gully stream where it crosses County Rd 11 (by the pump station), the first stream south of Cottage City Road on Lake Drive in Cottage City as it runs under Lake Drive, and the stream directly north of the Martin farm where it crossed Rt 364 were sampled on all sampling dates that they had running water. Jones Road at County Rd 11 was sampled on one occasion.
The stream at Seneca Point was sampled directly above the Bristol Harbor wastewater treatment plant, at the treatment plant outflow and just below where the stream crosses Seneca Point Road in order to determine the levels of E. coli coming from the treatment plant and their likely levels closer to where the stream enters the lake.
Results:
This project was intended to look at the health and safety of water with potential E. coli contamination in streams draining into Canandaigua Lake passing through and close by residential properties and to consider whether E. Coli in these streams might be contaminating near-shore areas used for swimming. In addition, where the shoreline is entirely on sewers, samples were taken along the road just before the streams cross into residential property.
We found that, although on many occasion streams had low or non-detectible levels of E. coli, after heavy storms some streams had extremely high levels and one public beach (Deep Run), very close to the mouth of a highly contaminated stream, had levels far exceeding safe recreational levels. On two occasions when our samples showed the public beach at Deep Run to be highly contaminated, it was open to the public for swimming with no warnings posted. The public beach at Vine Valley, which is not as close to the stream outlet, was not above safe recreational levels on any sampling occasion. It cannot be determined from our sampling if that is due to the distance from the mouth of the stream or the lake currents at that location. Further testing of shoreline areas near the mouth of streams likely to be contaminated after heavy storm events would help determine if and where swimming along the lake shore after a heavy rain is likely to be a health hazard. While much of the likely affected beach area is privately owned and not a public responsibility, it is heavily used for recreation and public warnings could be a public health benefit.
The extreme difference in E. coli levels in many streams between heavy storm events in April and June of 2023 indicated that the likely source of the contamination in most streams was from agricultural land, probably recently spread with manure. The low levels in April indicated that septic systems were unlikely to be the source in those streams. However, in October 2021 the Vine Valley stream had a higher E. coli count at the mouth of the stream than upstream where it drains directly from an agricultural field. One likely explanation is that the stream is being contaminated by septic fields as it runs down North Vine Valley Road, through Indian Village and the trailer park at Vine Valley. The water in the stream at that time was largely ground water derived since recent precipitation was fairly light and had largely infiltrated and there was no flow upstream near agricultural fields. Further sampling immediately upstream of these septic systems and at the mouth of the stream could document any improvement in water quality due to recent upgrades at Indian Village. The contamination found in October 2021 likely dissipated quickly as it was diluted by the lake due to very low flow and relatively low E. coli levels.
Samples at Seneca Point indicated that at the current time, given current levels of input to the treatment plant, the stream was mostly within safe levels of E. coli. There was one sampling occasion where the treatment plant effluent was high in E. coli but levels returned to close to safe recreational levels before they reached the lake. More consistent testing of the effluent could be warranted.
Further sampling recommendations
The primarily conclusions from this sampling are that streams from agricultural fields should be monitored more closely for E. coli after heavy precipitation events, especially during the spring and summer, as the streams could be a threat to public health if they are accessed by people or pets as they flow through residential areas, and that shoreline recreation near streams likely to have high levels of contamination should be sampled to determine how quickly contaminated stream water mixes with lake water to dilute bacterial levels to a safe recreational level. The Deep Run public beach should be more closely monitored for contamination after storm events to ensure people using that beach are not exposed to unsafe bacterial contamination.
Further segmented sampling from highly contaminated streams could determine the actual source of contamination, and water draining directly from field drains could be sampled to determine whether manure deposited on fields over tile drainage is contaminating road side ditches.
In some streams, especially where streams drain residential areas or in lake shoreline sampling, eDNA analysis could be helpful in determining the species of the source of the contamination.