Investigation of water quality and Sediment quality associated with the Muskegon County Wastewater Management System.

Transcription

1 Investigation of water quality and Sediment quality associated with the Muskegon County astewater Management System December, 7 Prepared for: Muskegon County astewater Management System Prepared by: Shikha Singh Research Assistant, Marc Verhougstraete Research Assistant, And Joan B. Rose, Ph. D. Homer Nowlin Chair in ater Research The ater Quality, Environmental, and Molecular Microbiology Laboratory Department of Fisheries and ildlife 1 Natural Resources Building Michigan State University East Lansing, MI 4884 Phone: (517) Fax: (517) rosejo@msu.edu

2 Introduction The Great Lakes and the surrounding watersheds are an important natural resource in Michigan. Surface water in the area is used for recreational activities such as fishing, swimming, and boating. Muskegon is located in western Michigan on Lake Michigan and boasts many inland lakes as well. Muskegon offers tourists many opportunities to enjoy activities on and near the water. Therefore, it goes without saying that the County of Muskegon must take every action necessary to protect and enhance this valuable resource. This project was conducted at the Muskegon County astewater Management System (MCMS) located near the Maple Island Road and Apple Avenue intersection. The MCMS uses full-mix, extended aeration, and storage lagoons as part of its sewage treatment system. After the lagoons, the water is sprayed onto the land by center pivot irrigation. The 5,1 acres of irrigated crops have a subsurface collection system 5-1 feet below the surface. Underdrainage from the fields is then piped to a surface ditch. This is a permitted discharge under the plants National Pollutant Discharge Elimination System (NPDES) permit. One parameter in the NPDES permit is fecal coliform counts established by the MDEQ. Recent tests indicate that the County of Muskegon was in violation of their NPDES discharge permit due to high fecal coliform concentrations found in the drainage ditch. However, the fecal coliform concentration meets permitted levels at the pipe prior to entering the ditch. The main question is whether exceedances are being caused by the discharge of poorly treated wastewater or if there is an external input into the ditch unrelated to the treatment plant? Another question is whether or not the sediments are reservoirs of microbial indicators which could be re-suspended into the water column? Contamination from fecal sources can cause water quality impairments both at the site and downstream to where recreational activities may be taking place. Due to the potential human and environmental health risks, it is important to ascertain the potential source of contamination to surface waters. Microbial indicators are used internationally to indicate whether or not fecal waste is contaminating the water column. Microbes used are typically those found in high concentrations within human faces. The U.S. Environmental Protection Agency (EPA) recommends E. coli and Enterococci to evaluate recreational water because both are present in human feces and Enterococci was found to be highly correlated with recreational illnesses (U.E. EPA 1986). The State of Hawaii uses C. perfringens as an additional indicator (Fujioka et al. 1985) which is indicative of past pollution. Coliphage is a virus that infects bacteria, specifically E. coli. The various types of coliphage may have some value as indicators, particularly for human enteric viruses (Havelaar et al. 199; Payment and Franco 199) and are generally indicators of recent pollution. Thus, these microbes would be useful indicators to evaluate water quality. Testing the sediment for bacterial indicators will help to determine if the sediment is acting as a reservoir for the microbes and contributing to NPDES exceedances.

3 The purpose of this study was: to evaluate the water quality from untreated sewage; evaluate the role of sediments in the process; and finally to evaluate the microbial removal treatment of this plant. Untreated sewage would be evaluated throughout the treatment process using routine and alternative indicators which will reflect human sewage impacts. Methods Samples were analyzed via the conventional water quality indicators fecal coliforms, Escherichia coli, as well as the alternative indicators Enterococci, the esp sewage marker in the Enterococcus faecium, and coliphage. Sample Collection: Five locations were selected for monitoring and samples were collected from each site 6 times over the course of the study. All samples were collected by Muskegon County staff and Michigan State University researchers. Two of the water samples were taken within the facility including the raw sewage influent and at the effluent from the full-mix lagoon. The remaining three water samples were taken from surface waters in the discharge ditch before, in, and after the re-aeration treatment prior to discharge to the Black Creek. and were sampled seven times (preliminary samples were obtained August rd, 7). ater samples were collected in sterilized plastic bottles using a grab sampler. Sediment samples were collected by using an inverted sterile hirl-pak bag. The six samples were obtained August 9, September 1, 19, 6 and October 1 and 17, 7. Table 1 describes the sample sites and photographs of the locations are provided below. Table 1. Sampling site Description and ID for the MCMS Study Sample ID and Description No. ater Samples No. Sediment samples : Untreated sewage entering the 6 None facility; no treatment : Large primary tank providing 6 None aeration treatment : The discharge to the ditch after land 7 7 application before re-aeration device AT: In the re-aeration tank in the ditch 6 None : At the weir, discharge into black creek 7 6

4 Photographs from the Sampling Sites associated with the MCMS study Raw sewage () Primary Treatment () Ditch water before it enters the re-aeration and empties into Black creek () Ditch sediment at site 4

5 Discharge after re-aeration Re-aeration Tank Aeration area Bacterial indicators: Membrane Filtration Volumes for bacteriological analysis via membrane filtration ranged from one milliliter (ml) with up to a 1-6 dilution and as much as ml. ater samples were analyzed for E. coli following the EPA approved method 16 (US EPA 6) which consists of membrane filtration and mtec agar. The first two sediment samples were also analyzed for E. coli using membrane filtration and mtec. Since the sediment samples were too turbid to filter large volumes needed, Colilert kit by IDEXX was used for the remaining samples. Enterococci were analyzed using membrane filtration according to USEPA Method 16 (Enterococci) (US EPA, ). Coliphage were analyzed via a modification of USEPA Methods 161 and 16 (US EPA, 1). (Table includes the media and conditions for monitoring these bacteria) Table. Media and Methods used for Microbial Indicator Testing Test Media Incubation Reference Fecal coliform mfc 44.5 C 4 hours APHA Standard Method 9D E. coli mtec and 4-8 hours at APHA Standard Method 7 C 9B Colilert 4 hours 6.5 C (sediment) Enterococci mei agar 4 hours at 41 C USEPA Method 16 Coliphage Tryptic Soy Agar 16 4 hours at 7 C () USEPA Method 161/16 (1) 5

6 Enterococci esp analysis The Enterococci bacteria which grew up on the membrane filter as assayed above were washed off the membrane and extracted (Scott et al., 5 and Kumar, 7). The primers specific for the esp gene in E. faecium previously developed and examined for specificity to human fecal pollution were used in a polymerase chain reaction (PCR). The forward primer: (5 -TAT GAA AGC AAC AGC ACA AGT- ) and the conserved reverse primer (5 ACG TCG AAA GTT CGA TTT CC- ) were used for all reactions. Gel electrophoresis was performed on the PCR product and run on a 1.% w/v agarose gel at 95 V for approximately one hour. Bacterial sediment analysis The sediment sample was weighed out and 1 g was diluted 1 fold using phosphate buffer water (9 ml of PB) in a sterile centrifuge tube. The sample was vortexed for one minute, followed by a vigorous hand shaking for seconds, vortexed again for 1 minute followed by a final hand shaking for seconds. The eluent was pipetted out of the centrifuge tube and placed in a sterile container. For each test, 1 to 5 ml of the eluent was analyzed. Dry weight was analyzed after drying in an oven for 48 hours at 6 C and compared to wet weight. In order to measure E. coli, 1 ml samples were assayed in a Quanti-Tray/ (QT- K) using the IDEXX (estbrook, Maine) Colilert ( ). If Bacterial counts exceeded the detection limits of the systems, samples were diluted with a sterile phosphate buffered water solution and the dilution was reprocessed. Generally 5 to 1 ml of the sediment eluent was assayed (for the eluent procedure see below). Assays were conducted by adding the sample to a powdered reagent (Colilert for E. coli) in a sterile container, mixing until reagent was dissolved, and then sealing in a Quanti- Tray/ plate. Colilert samples were placed in a 6.5 C incubator for 4 hours. The sediment eluent for all other bacteria and viruses were assayed as described for the water samples. Coliphage Analysis Agar overlays were utilized to detect coliphage present in the samples. Filtered volumes of the water sample were used to enumerate coliphage. Two types of overlays were conducted one using E. coli F + amp as a host, the other using E. coli C. The F + amp is known as male specific coliphage and infect the host at the F-pili. Somatic coliphage (C) infect the host bacteria at the outer cell wall. Setting up overlays for coliphage analysis was preformed in the following manner: For each sample, ml were syringe-filtered through a.45 micron filter..5mls of host and ml of sample were added to melted top agar before mixing and pouring onto a tryptic soy agar plate (TSA). Two negative control plates were made, one with each host, by adding 1.5mLs host to the top agar, mixing and pouring onto a TSA plate. A positive control was run for each host type by adding 1.5mLs host to the top agar, mixing and pouring onto a TSA plate. Stock MS- phage was spotted onto the hardening agar layer. For each sample, 5 overlays of each host type were performed. Overlays were incubated 6

7 at 7 C for 4 hours and then assessed for plaque formation. A plaque formation appears as a circular zone of clearing generally in the 1-1 mm diameter range (US EPA 1 Method 16) Adenovirus Analysis Between 1.5 to. L of water samples were filtered through a 9 mm, negatively charged HA membrane with pore size of.45-μm (Millipore, Billerica, Mass). After filtration, 1 ml of.5 mm H SO 4 was filtered to rinse out excess ions. Viral particles were eluted from the filter and stored at - C before further concentration. For further purification and concentration, the elutant was thawed and dispensed into an Amicon Ultra 1K concentrator column (Millipore). Eluate was centrifuged at 4 x g for 1 minute and the resulting filtrated was discarded and column filled with 1 ml PBST (ph 8.). Column was centrifuged again at 4 x g for 1 minute. After centrifuging, the sample concentrated was removed and stored at 8 C until further processing. Adenovirus RNA/DNA was extracted using Qiagen RNA viral kit. The sample was concentrated using an Amicon Ultra-15 concentrator column and centrifuged for minutes at 4x g. This process was repeated until all the eluate was used. DNA was subsequently extracted using the UltraClean Isolation Kit (Carlsbad, CA). A nested PCR reaction was performed to amplify the hexon gene of all 51 human adenovirus prototype strains (Jiang et al. 1). Gel electrophoresis was performed on the PCR product and run on a 1.% w/v agarose gel at 9 V for approximately one hour. Results: ater samples The average ph, water temperature, air temperature, and turbidity at each of the sampling sites are shown in Table. There was very little difference in ph (7.5-8.), water temperature 16 to 6 o C, and air temperature 1-15 o C. The untreated wastewater was warmer with a slightly lower ph. The turbidity was very high in the untreated and primary wastewater and was reduced by 95.% via land application. Table Geometric average of environmental and water parameters measured during time of obtaining samples Site ph ater Temp ( O C) Air Temp ( o C) Turbidity (NTU) AT The following table (4) shows the prevalence and concentrations of the bacteria and coliphage in the untreated wastewater influent, post primary treatment, after land application in the discharge to the ditch, and pre/post re-aeration in the ditch prior to discharge to the Black Creek. Figures 1a through 1d show the geometric means of each 7

8 fecal indicator compared at each site. All samples tested positive for fecal coliforms, E. coli and Enterococci. All raw sewage and primary treatment samples tested positive for both the somatic and the F-specific coliphage. Site tested positive for both types of coliphage 4 out of the 7 samples (57%). Site AT tested positive for both sets of coliphage in 4 of the 6 samples (67%). Site tested positive for the F-specific coliphage in 4 of the 7 samples (57%) and of the 7 samples (9%) for the somatic coliphage. Table 4. Bacteria and Coliphage concentrations throughout the treatment process at the MCMS Fecal coliform E. coli Enterococci Coliphage F amp Coliphage CN-1 #samples % Min.7E+6 1.5E+6.8E+5 9.E+4 7.6E+4 Max 5.86E+7 5.E E+6 7.6E+5 7.9E+5 Geom. Avg 1.E+7.89E E+5.4E+5.9E+5 #samples % Min 1.57E E+4 1.7E+4 4.E+1.E+1 Max 1.5E+6 1.1E E+5 1.8E+5.E+5 Geom. Avg 1.48E+5.87E+4.5E+4 1.4E E+4 #samples % Min 6.47E+1 4.7E+1 6.9E+1 <1 <1 Max 7.E+ 7.57E E+.E+1 6.E+1 Geom. Avg 1.4E+ 6.11E E+ 1.7E+1.78E+1 AT #samples % Min.5E+1.4E+1 1.5E+ <1 <1 Max 1.E+ 8.E+1 1.6E+.E+1 8.E+1 Geom. Avg 9.91E E+1.96E+ 1.E+1.99E+1 #samples % Min 4.1E+1.1E E+1 <1 <1 Max 6.8E+ 8.8E E+ 7.E+1 1.E+ Geom. Avg 1.16E+ 5.E E+.14E+1 6.9E+1 Note: Concentrations are shown as CFU or PFU / 1 ml 8

9 Figure 1. Concentration of fecal indicator bacteria in water samples for fecal coliforms (a), E. coli (b), Enterococci (c) and two coliphage types (d and e) a) 1.E8 1 Fecal coliform (cfu/1 ml) logscale AT Sampling Sites b) 1.E8 1 E. coli (cfu/1 ml) logscale AT Sampling Sites 9

10 c) 1.E8 1 Enterococci (cfu/1 ml) logscale AT Sampling Site d) 1.E8 1 CN-1 coliphage (pfu/1 ml) logscale AT Sampling Site 1

11 e) 1.E8 Famp coliphage (pfu/1 ml) logscale Sampling Site AT Removals by Treatment Table 5 and Figure show the removals by the treatment processes. Fecal coliforms and E. coli are removed to a greater extent than Enterococci and coliphage. Primary treatment in the lagoon removes only between 9% and 99% of bacteria and viruses, where as land application removes 99.5% to 99.9%. There is little removal in the ditch itself or via the re-aeration tank at the weir. Overall the treatment removes, % of fecal coliforms, % of E. coli, 99.96% of Enterococci, and and 99.98% of the two types of coliphage. Table 5. Percent removals of bacteria and viruses through the various treatments at the MCMS PROCESS Fecal Coliphage Colipahge E. coli Enterococci coliform F+amp CN-1 Primary treatment Land application Ditch Re-aeration tank Total removal

12 Figure. Log 1 Removals of bacteria and viruses through the various treatments at the MCMS Log 1 removals Fecal Coliforms E.coli Enterococci Coliphage famp Coliphage. by primary trt by land application in ditch by aeration total removal Sediment moisture analysis Sediment samples were dried to assess the moisture content of the material. Table 6 indicates the average of the percent dry weight of the sediment samples. Dry weight percentages of samples ranged from 71-8%. Dry weight percentages of sediment samples ranged between 45-79%. Table 6. Geometric average of moisture content of sediment samples Sample % Dry eight sediment 77.7 sediment Site had ten fold higher concentrations (1 4 per 1 g dw) of fecal indicator bacteria compared to site (1 per 1gdw). In general, fecal coliform concentrations were slightly higher then E. coli and Enterococci concentrations at both and sediment sites. The concentrations of the fecal indicator organisms in the sediment samples at both and sites are displayed in Table 7 and Figure. Fecal coliforms were detected in 6 of 7 sediment samples at and in all 6 samples for sediment from site. E. coli was detected in 4 of 7 samples from and in all samples from site. Enterococcus was detected in all sediment samples at both sites. Somatic and F-specific coliphage were not detected in any of the sediment samples from site. F-specific coliphage was detected in 1 of the 6 sediment samples (somatic coliphage at 66.4 PFU/1 g dw). Figure shows the concentration of fecal indicators at the two sites in log scale per 1 gram dry weight (cfu/1 g dw). 1

13 Table 7. Bacteria and Coliphage sediment sample levels before and after aeration in the Ditch Fecal Coliphage Site coliform E. coli Enterococci F+amp Coliphage CN-1 #samples % Min <6 <65.1E+ <1 <1 Max 7.1E E+.81E+4 <1 <1 Geom. Avg 7.7E+.57E+ 4.9E+ <1 <1 #samples % Min.4E+ 5.66E+.65E+ <69.1 <4. Max 8.76E+5 8.4E+5.81E+4 < E+ Geom. Avg 5.15E+4.4E+4.68E+4 <1 6.64E+ *only one sample tested positive for Coliphage in sediment Note: Concentrations are shown as CFU or PFU / 1 g dw Figure. Concentrations of fecal indicators fecal coliforms (a), E. coli (b), Enterococci (c), coliphage (d-e) in sediment samples a) 1.E8 1 Fecal coliform (cfu/1 g dw) logscale Sampling Sites 1

14 b) 1.E8 1 E. coli (cfu/1 g dw) logscale Sampling Site c) 1.E8 Enterococci (cfu/1 g dw) logscale Sampling Site 14

15 d) 1.E8 Famp Coliphage (pfu/1 g dw) logscale Sampling Sites e) 1.E8 CN1 Coliphage (cfu/1 g dw) logscale Sampling Sites 15

16 esp marker analysis DNA was extracted from Enterococci colonies that grew on the membrane filters. The polymerase chain reaction was used to amplify the DNA esp marker (Scott et al., 5). According to the results obtained from this method, the esp marker was detected on October 1 th, 7 at sites AT and. Enterococci concentrations in the water for AT and were 16 cfu/1 ml and cfu/1 ml respectively on that day. Table 8 displays the results of the esp marker analysis. Table 8. esp marker results for water samples Site # of membranes processed 8/9/7 9/1/7 9/19/7 9/6/7 1/1/7 1/17/7 TOTAL 8/9/7 9/1/7 9/19/7 9/6/7 1/1/7 1/17/7 Total 8//7 8/9/7 9/1/7 9/19/7 9/6/7 1/1/7 1/17/7 Total AT 8/9/7 9/1/7 9/19/7 9/6/7 1/1/7 1/17/7 Total 8/9/7 9/1/7 9/19/7 9/6/7 1/1/7 1/17/7 Total Range of CFU/membrane TNTC TNTC 67-TNTC TNTC TNTC TNTC TNTC 1-TNTC TNTC TNTC 76-TNTC TNTC 111-TNTC TNTC TNTC 41-TNTC Esp positive membranes % membranes Positive for ESP

17 Adenovirus samples 17

18 Each site within the MCMS was analyzed for the adenovirus using the previously described methods. The conventional PCR results indicate that sites and had the adenovirus present during every sampling event. Sites, AT, and tested negative for adenovirus during every sampling event. The adenovirus was detected at site in as little as 6 (9/1/7) ml and with a concentration as low as.4 ml (9/6/7). At site, the adenovirus was detected in as little as 7 ml (9/1/7) and at a concentration as low as.5 ml (9/1/7). Discussion The data indicates that the total treatment process is able to remove , and % of the FC, E. coli and Enterococci bacteria, respectively and 99.99% percent of the coliphage virus. There is evidence that low levels of microorganisms originating from the wastewater facility (via the detection of esp and coliphage) remains in the effluent discharged to the ditch and is subsequently discharged to Black Creek. The sediments are contributing to the increased levels of fecal coliforms, likely resulting in the exceedance of the NPDES permit. There is no statistical change in microbial numbers before and after aeration in the ditch. Fecal coliform bacteria and E. coli (a member of the FC group) and Enterococci are the most commonly used bacteria for judging fecal pollution of water. These bacteria likely re-grow in the environment, especially during summer months (e.g. on algae and in soil and sand). The coliphage (virus indicator, infects E. coli) does not re-grow in the environment and it s survival in the environment is finite compared to the bacteria and usually indicates more recent pollution. Sediments are a source of the bacteria but only on occasion a source of the coliphage. The esp marker associated with the wastewater is reduced in prevalence from 8% in the untreated influent and primary treated effluent to 17% in the ditch and discharges. The esp marker test is based on a cultivation method followed by PCR. It is found in untreated sewage, 1% of the time, detects only live bacteria (Scott et al., 5; Kumar, 7) and to date our laboratory has never detected it in animal wastes. This study indicates the presence of fecal indicator bacteria in the surface water before and after the re-aeration mixing tank in the field (AT). Fecal coliform concentrations were extremely high (>68 cfu/1 ml) on September 6 th, 7 at all water samples taken from the field (, AT and ). On several occasions, water samples had high concentrations of Enterococci (>1 cfu/1 ml) in samples taken from the field sites ( and ). Several of these samples exceeded the EPA and MDEQ criteria and standard respectively for single samples taken for recreational levels (see appendix C). Twenty-eight to 66 percent of the water samples also contained the coliphage virus at the field sites (, AT and ). Coliphage virus is generally indicative of recent sewage pollution as it does not regrow in the field. Both AT and tested positive for the human esp marker when Enterococci concentrations were above 95 cfu/1 ml. The water 18

19 released from re-aeration tank into the creek has on occasion high concentrations of Enterococci which EPA has found to be highly correlated with recreational illness when swimming in the water. In conclusion: The MCMS includes processes that remove via land application 99.9 to % of the viruses and bacteria. The discharged effluent quality in the ditch does not change before and after the re-aeration and the enterococci esp marker is found on occasion in the waters in the ditch receiving the effluent. The coliphage also shows this impact. The continual loading of effluent has seeded the sediments which are likely a source of the fecal coliforms influencing the NPDES violations. 19

20 References American Public Health Association, American ater orks Association, and ater Environment Federation Standard Methods for the Examination of ater and aste ater 19 th Edition. Section 9. Bisson J.. and V.J. Cabelli Membrane filter enumeration method for Clostridium perfringens. Applied and Environmental Microbiology, 7(1): Fujioka R.S. and Shisumura, L.K Clostridium perfringens, a reliable indicator of stream water quality. J ater Pollut Control Fed, 57, 1, Jiang, S., Noble, R. and Chu,. 1. Human adenoviruses and coliphages in urban runoff-impacted coastal waters of Southern California. Appl. Environ.Microbiol. 67: Kumar, L. 7. Development Of A Rapid Method For A Human Pollution Source Tracking Marker Using Enterococcus Surface Protein (Esp) In E. Faecium A THESIS Submitted to Michigan State University, in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Fisheries and ildlife, E. Lansing MI Scott, T. M., Jenkins, T.M., Lukasik, J and Rose, JB. 5. Potential Use of a Host Associated Molecular Marker in Enterococcus faecium as an Index of Human Fecal Pollution; Environ. Sci. & Tech. 9: (1) 8 87 U.S. Environmental Protection Agency (EPA) Ambient water quality criteria for bacteria, EPA A44/5-84-, US EPA, ashington, DC. U.S. Environmental Protection Agency (EPA). 1. Method 161: Male - Specific (F+) and Somatic Coliphage in ater by Two - Step Enrichment Procedure. EPA 81- R-1- Office of ater, ashington D.C. U.S. Environmental Protection Agency (EPA). 1. Method 16: Male - Specific (F+) and Somatic Coliphage in ater by Single Agar Layer (SAL) Procedure. EPA 81-R-1-9. Office of ater, ashington D.C. U.S. Environmental Protection Agency (EPA). 6. Method 16: Escherichia coli (E. coli) in water by membrane filtration using modified membrane-thermotolerant Escherichia coli agar (modified mtec). EPA 81-R Office of ater, ashington D.C.

21 Appendix A. Raw data for water samples. All values reported as CFU/1 ml water Site and Sample DateID Fecal coliform E. coli Enterococci C. perfringens Coliphage Famp Colipahge CN-1 8/9/ /1/ /19/ /6/ /1/ /17/ /9/ /1/ /19/ /6/ /1/ /17/ // /9/ /1/ /19/ <1 <1 9/6/ <1 <1 1/1/ /17/ <1 <1 AT 8/9/ AT 9/1/ AT 9/19/ <1 <1 AT 9/6/ AT 1/1/ AT 1/17/ <1 <1 8// <1 <1 8/9/ /1/ <1 <1 9/19/ <1 9/6/ <1 <1 1/1/ /17/ <1 1

22 Appendix B. Raw data for sediment samples. All values reported as CFU/ 1 g dw (g dw = gram dry weight) Site and date sampled Fecal coliform E. coli Enterococci Coliphage Famp Colipahge CN-1 C. perfringens sed 8// <64 < sed 8/9/ <645. <645. sed 9/1/ < <167.9 <167.9 sed 9/19/7 < <6.8 <6.8 sed 9/6/ < < sed 1/1/ < <619.4 <619.4 sed 1/17/ < <65.1 <65.1 sed 8/9/ <69.1 <69.1 sed 9/1/ <4 <4.8 sed 9/19/ <91.5 <91.5 sed 9/6/ <4. <4. sed 1/1/ <174.9 <174.9 sed 1/17/ < *Note that C. perfringens was only assayed for one days sample due to supplier distribution issues and was unable to be shipped to the lab

23 Appendix C. Fresh water quality guidelines and standards (CFU/1 ml) for areas of recreational use. Geometric Mean a Single Sample Maximum US. EPA Enterococci E. coli MDEQ E. coli 1 a based on five or more samples equally spaced over a -day time period MDEQ: Michigan Department of Environmental Quality Bacterial ater Quality Standards for Recreational aters (Freshwater and Marine aters).. (EPA-8-R--8). USEPA. Office of ater. ashington, D.C.