Water Quality Monitoring in the Upper Winooski River Headwaters 2010 Bacteria and Nutrients Within the towns of Cabot-Marshfield-Plainfield Photo - Eastern pearlshell Margaritifera margaritifera at martin Bridge - Steve Fiske By Steve Fiske For Friends of the Winooski River in Cooperation with The Conservation Commissions of Cabot, Marshfield, and Plainfield With support from The Vermont Department of Environmental Conservation R.A.LaRosa Grants Program November 30, 2010 Acknowledgments The Friends of the Winooski River in Cooperation and the Conservation Commissions of Cabot, Marshfield, and Plainfield; would like to recognize and give a BIG THANK YOU to the volunteers who collected water quality samples and made this effort possible. These include longtime volunteers Clay Whitney, Allen Banbury, George Springston, Allen Clark, Susan Alexander and Steve Fiske. As well as the much appreciated and needed enthusiasm of our 2010 volunteers that did an exceptional job Sue Freeborn, Rob Maier, Jacqueline Soule, and Lillian Alexander. All the above sacrificed sleep for early morning sampling throughout the summer, a Sunday afternoon or two, and the last minute bottle exchanges to get samples to Waterbury in time for analysis. This report was greatly helped by the proofing - editing skills of Allan Clark, and Karina Dailey, and the GIS map figures by Karina. We would also like to recognize the efforts of our grant writer, and coordinator Ann Smith from the Friends of the Winooski River who made sure grants, quality assurance project plans, and bottle orders were in on time. Introduction In 2010 the focus of water quality monitoring in the upper Winooski River involved three components: A fecal coliform bacteria survey (E.coli) of numerous locations along the main stem of the Winooski River, strategically bracketing potential sources of bacteria, including sampling two tributaries (Jug Brook, and Wells Brook) potential bacteria sources, and additionally the Marshfield Reservoir for the first time. A nutrient survey of phosphorus and nitrogen targeting the effect of the Waste Water Treatment Facilities (WWTF) within the three towns, and continuing to characterize the water quality of Naismith Brook (a very high quality stream), and the Winooski River at the Martin Bridge (a highly significant rare mussel location). Finally we continued on the limited 2009 effort to begin to characterize the effect of Hydro power generation flows on the water quality of the Winooski River in Marshfield. E.coli - Bacteria Fecal coliform bacteria are a particular group of bacteria primarily found in human and animal intestines and wastes. Escherichia coli (E. coli) is one of the fecal coliform bacteria widely used as an indicator organism to show the presence of such wastes in water and the possible presence of pathogenic (disease-producing) organisms. When E. coli is found in waters, its presence is not the problem of concern itself but is rather an indicator of the presence of fecal contamination (most strains of E. coli are not pathogenic) from humans or animals. E. coli monitoring is commonly conducted to ensure that the water is safe for swimmers and other contact recreational activities; a relationship can often be established between high bacteria concentrations and its sources such as rainfall runoff from urban streets, waterfowl or other wildlife congregations, pastured animals, and untreated waste (septic) water. Bacteria are measured in organisms or colony-forming units per 100 milliliters of water (cfu/100 mL). Vermont’s Class B water quality standard sets the maximum tolerable E. coli level at 77 colonies per 100 ml of sampled water. This is a very conservative standard and translates into a potential risk of contracting a gastrointestinal health illness of <4 people in a 1,000 after ingestion of water. The federal Environmental Protection Agency (EPA) currently recommends a slightly less stringent standard of 235 cfu/100mL. This equals a risk factor of about 8 illnesses/1,000 ingestions. In 2010 bacteria monitoring targeted the main stem of the Winooski River, bracketing potential sources of bacteria based on the bacteria results from 2007 and 2008. The 2007/8 results showed bacteria levels exceed the Vermont and sometimes the Federal EPA water quality standards on all sites except Upper Cabot- below the upper recreational fields in town (2007 and 2008 WQ monitoring reports). Based on the location of the main stem sampling sites it appears E.coli bacteria loading may be coming from the following locations: 1) Jugg Brook; 2) Creamery Street in Marshfield; and 3) Plainfield village. The largest spikes were observed in 2007 following rain events in lower sections of the sampling area- Plainfield. Sampling locations selected in 2010 are presented in Table 1 below, which bracket potential bacteria sources. Sample locations are also presented in figures 3 to 6 in back of report. The uppermost location on the main stem is at River Mile (RM) 85.5 at Larry’s Ballfield. The next down stream location 84.1 brackets both Jug Brook 0.1, and a pastured un-buffered reach of stream (grazing to the edge of the stream/into the stream?). RM 83.8 then brackets the Cabot WWTF, located just below RM 84.1. Table 1 Bacteria and or Nutrient sampling site locations 2010 Location Site ID - RM Latitude Longitude Description Winooski River WIN 70.7 44.16240 72.25560 Below Plainfield WWTF, at Rip Rap bank. WIN 71.3 44.276068 72.42885 Above Plainfield WWTF, below. Great Brook WIN 71.4 44.27750 72.42576 In village of Plainfield at Dam/Park, above. Great Brook WIN 72.8 44.28710 72.40900 Above village of Plainfield, at Martin Bridge WIN 78.1 44.3223301 72.37967 Mid Winooski – Patty’s Xing WIN 81.6 44.20500 72.21370 Below Marshfield WWTF and Marshfield Pond Brook @ flower farm WIN 81.8 44.35014 72.35657 Above Marsh WWTF, Below Creamery St. trib. WIN 82.6 44.35193 72.347528 Above Marshfield Village, at Rt 2 bridge, below hydro gen. station. WIN 83.8 44.22590 72.19580 Below the Cabot WWTF, behind Durrant Cemetery. WIN 84.1 44.39093 72.33078 Above Cabot WWTF, just above Saw Mill Rd, Below Jug Brook WIN 85.5 44.23580 72.19260 Below Cabot Village at Larry’s Ballfield Jug Brook JB 0.1 44.39230 72.33102 At mouth, adjacent to Lower Cabot Village store Nasmith Brook NS 0.3 44.30083 72.39367 About 100m above mouth Wells Brook WB 0.1 44.28341 72.41726 At mouth, just above Route 2 Reservoir RES 01 44.36289 72.30242 At boat launch The next location downstream shifts to the Marshfield Village area, with RM 82.6 just above the Village, RM 81.8 below Creamery Street, and above Marshfield WWTF, and finally RM 81.6 bracketing the WWTF at the flower farm. Two mid Winooski locations were sampled; one at Patties Xing RM 78.1, and one at the Martin Covered Bridge RM 72.8. The Martin Bridge is also just above Plainfield Village, with the next location RM 71.4 being at the Plainfield Village Park, immediately below the dam. Wells Brook also enters the Winooski River between these two sites. The last two main stem locations are located below Great Brook, and bracket the Plainfield WWTF with RM 71.3 above the WWTF, and 70.7 below. Results and discussion In 2010 a total of six bacti samples were collected from each site. Five of the sampling events were under “baseflow” conditions when stream recreational activities are at their highest. One sample collected on August 3rd was collected under high flow runoff conditions. This sample was very high in bacti at all sites with most sites having counts of >2,000 cfu/100mL. This high bacti level associated with very high turbid runoff events was documented in 2007 and 2008, and indicates a high bacteria level in the sediments of the river, and those sediments washed into the river during these events. Fortunately no contact recreation occurs during these events, however it does show that bacteria risk increases after rain events. One additional sample was collected at RM 82.6 during the sampling run on July 20th immediately after the hydro station began generation. This sample was collected to see how the operation of the hydro facility during generation flows affect the bacteria levels of the river. The results show that bacteria levels doubled during hydro generation flows at RM 82.6. Bacteria counts went from 548 to 1120 cfu/100mL in samples collected during base flows and then during hydro generation flows respectively. Turbidity at the same time rose from 1.5 to 4.6 NTU. This increase in turbidity is noticeable but is not extremely turbid. The increased levels of bacteria are likely associated with river bed sediments being re-suspended. While high flows may discourage river swimming and fishing; both kayaking and canoeing may actually increase, and the high bacteria levels associated with these flows may increase the risk of gastrointestinal health problems. The results of the “baseflow” sampling are presented in Figure 1. In this figure the sample locations from Cabot, and progressively downstream thru Marshfield and Plainfield are located from left to right on the graph. Potentially significant sources of bacteria that are bracketed by the station locations are also indicated. The two tributaries and the reservoir sites are shown on the far right hand side of graph. The data represent the bacteria geometric mean (BGM) of all five base flow samples for each site. The bacteria geometric mean from the uppermost site, RM 85.5 on the Winooski main stem, and the two tributaries were all below both the Vermont Water Quality Standard (VTWQS), and Federal Environmental Protection Agency (EPA) recommended water quality criteria of 77 cfu/100mL, and 235 cfu / 100mL respectively. The Reservoir had the lowest bacti counts of all locations sampled. The reservoir also has the highest recreational use in the area and these low bacti counts indicate that contact recreation is supported and safe from elevated bacteria. Moving downstream on the main stem, the geometric mean increases to just above the VTWQS at RM 84.1 from a BGM of 51 to 118 cfu/100mL. This is likely due mostly to the influence of the pastured reach between these two locations, since Jug Brook which is also between these two locations only had a slight contribution with BGM of 67 cfu/100mL. Samples collected above and below the Cabot WWTF RM 84.1 – 83.8 showed very little increase in the BGM, indicating the Cabot WWTF is not a significant contributor of bacti to the Winooski river. Figure 1: Bacteria Geometric Mean results by river mile station. Also shown are VTWQS, and EPA WQS for bacteria, and location of landuse activities and WWTF in relation to sampling locations. Bacteria results during "base flows" from Upper Winooski River 2010400 JB 0.1 RES 01 WB 0.1W 70.7 W 71.3W 71.4 W 72.8 W 78.1 W 81.6 W 81.8 W 82.6 W 83.8W 84.1 W 85.5 400 JB 0.1 RES 01 WB 0.1W 70.7 W 71.3W 71.4 W 72.8 W 78.1 W 81.6 W 81.8 W 82.6 W 83.8W 84.1 W 85.5 Geometric Mean of Bacti cts 300 200 100 235 EPA WQS 77 VT WQS 0 .584 1 85 8.881 CWWTF PWWTF Animal MWWTF Pasture River Sites # = River Mile At the next location downstream is just above Marshfield at Rt 2 RM 83.6. The bacti levels appear to increase again from a BGM of 127 to 242 cpu/100Ml. The immediate Winooski river corridor is again dominated by pasture and hayfield between these locations, as well as some residential housing near Marshfield. These could all be possible bacti sources. Thru Marshfield village, above and below the Marshfield WWTF, the BGM levels decrease slightly indicating that the village residential housing, Creamery Brook, and the MWWTF all do not contribute significantly to the bacti loading of the Winooski River. The next location, in the mid Winooski by Patties Xing, bacti levels were basically at VTWQS, indicating that contact swimming use in this area is generally meeting an acceptable risk. Moving downstream to the Martin Bridge location RM 72.8( just above Plainfield village) and Wells Brook, the BGM increases to 162 cfu/100mL, which is above the VTWQS 77 but below the EPA WQS 235. Between these locations, the immediate river corridor is occupied by a vegetable cooperative, Twinfield Union School, two campgrounds, and a dairy pasture/hay lands. This level of increase in bacteria is not a high priority concern, but should be monitored as the Martin Bridge is a significant location for contact recreational use of the river. The next three locations are within the village of Plainfield. At the first location, immediately below the dam, the BGM was over twice that found at the Martin Bridge, and the highest found in the main stem with a BGM of 371 cfu/100mL. This is above both the VTWQS, and the EPA WQS for acceptable swimming risk. It does not appear that Wells Brook is the source of the increased bacti levels, since the BGM of samples collected from it were very low at 12 cfu/100mL. One must conclude that the bacteria source below the dam site at RM 71.4, is below the Wells Brook confluence at the dam in Plainfield. The dominant use adjacent to the river in this reach is residential housing, and small business. Since this location has significant swimming use, the source of the elevated bacteria levels should be further explored. The last two sampling locations bracket the Plainfield WWTF, below Great Brook. Bacteria levels at these sites were generally lower than below the dam but still above both WQS for bacti risk. No significant difference was found between the two locations, indicating that the Plainfield WWTF is not a significant source of bacteria in the village. It also appears that Great Brook does not add significant levels of bacteria to the main branch since bacti levels drop between RM 71.4 and 71.3 above and below its confluence with the Winooski River. Nutrients Nutrients can be a water quality concern because they can stimulate algae growth in a river. While algae growth is not detrimental at low levels, if algae growth becomes prolific it can become detrimental to the biological integrity of the river and can be aesthetically unpleasing during swimming or boating. Nutrients were sampled above and below each towns waste water treatment facility (WWTF) three times during “base” flow conditions. This data will help determine both the contribution of each treatment plant to the Total Phosphorous (TP) and Total Nitrogen (TN) loading to the upper Winooski River, and eventually Lake Champlain. This data will also be valuable for the villages WWTF’s in their NPDES permit renewals, as the EPA and VTDEC begin to incorporate nutrient water quality criteria into the WWTF NPDES permits of each town. Additionally nutrients were sampled from three other locations, Just above Marshfield village, below the Hydro facility RM 82.6, and at the Martin Covered Bridge site RM 72.8 on the main stem of the Winooski River, and from the Naismith Brook 0.2 tributary. The latter two of these locations were sampled to continue building a database from these two long-term ecologically important locations. The hydro facility site RM 82.6 is being sampled to build a database on how the water quality of the Winooski River as it flows thru the village of Marshfield is affected during generation flows from the hydro facility. WWTF Nutrient results. Both Total Nitrogen (TN) and Total Phosphorus (TP) were well below nutrient criteria levels being considered by the VTDEC for medium sized streams (TN 75mg/l, and TP 35ug/l), see figure 2 . Total nitrogen was highest below the Cabot WWTF where it averaged 0.45 mg/l. This is a significant (p=0.007) increase from above the WWTF where the mean was 0.26 mg/l. No significant increases in TN were found associated with the Marshfield or Plainfield WWTF’s. The mean TP was below 20 ug/l at all locations, except below the Martin Bridge where it was 25.2 ug/l. The slightly elevated TP mean at this site was mostly due to a single sample collected when the turbidity at this one location was higher then that of all others on the collection date of 8/16/2010. The turbidity was over twice that of all other sample locations for the date at 7.1 NTU. TP averaged only 15.3 ug/l for the other two sampling events at this site. It is not known why the turbidity was elevated at this location - one possibility however is that the sample may have been subject to some influence from hydro generation flow passing thru the location. Hydro generation flow effects on WQ- Nutrients and Turbidity From 2009 thru 2010 five base-flow and four hydro-generation flow water quality samples were collected at RM 82.6 in the Winooski River. No significant difference in the TN was observed between these flow rates. Total phosphorus and turbidity however were significantly elevated during hydro-flow event samples compared to base-flow. Total phosphorus increased from an average of 11.6 ug/L to almost 27.0 ug/L (p=0.006), an increase of 140%. Much of the increase in phosphorus appears to be associated with the increase in particulates in the river during hydro-flow conditions. Turbidity significantly increased from an average of 1.1 NTU’s to 4.9 NTU’s (p=0.001). While this increase in turbidity is below a typical 10 NTU standard for cold water habitats it is a noticeable increase to the casual observer. Figure 2 : Nutrient concentrations during base flows above and below the three WWTF’s in the upper Winooski River. TN from upper W inooski 2010 0.6 0.5 0.4 0.3 0.2 0.1 0.0 TP ug/l TN mg/l W Q Site - RM and locations of W W TF C WWTF M WWTF P WWTF TP from upper W inooski 2010 50 40 30 20 10 0 M-WWTF P-WWTF WQ Site RM and location of W W TF C-WWTF Table 2: Nutrient concentrations during B-Base and H-Hydro flow conditions at RM 82.6, in the Winooski River. Data from 2009 and 2010. Site RM TN mg/l TN mg/l TP ug/l TP ug/l Turb NTU Turb NTU flow B H B H B H 82.6 0.39 0.41 12.30 20.20 1.56 4.49 0.28 0.28 9.05 37.80 0.84 5.87 0.34 0.35 10.68 29.00 1.20 5.18 0.28 0.35 9.05 20.90 0.84 4.22 0.23 16.80 1.30 mean 0.30 0.35 11.58 26.98 1.15 4.94 Conclusions and recommendations Bacteria levels continue to be low in the tributaries of the upper Winooski, as well as in the Marshfield Reservoir. The main stem of the Winooski however appears to consistently meet VT WQS only immediately below Cabot Village. From lower Cabot thru Marshfield, to the Martin Bridge bacti levels are generally above the VT WQS of 77 cfu/100mL, but below the EPA 235 cfu/100mL. This indicates a slight increase or chronic level of bacti contamination. All three locations within the village of Plainfield were above both WQ bacti standards, indicating a greater level of risk to swimmers. The highest levels were measured immediately below the Dam in Plainfield village. It is recommended that the source of the bacteria contamination in Plainfield be determined so that the sources can be corrected. In general it is recommended that bacteria monitoring continue at a few core locations where swimming use occurs on the main stem of the upper Winooski since a chronic level of contamination exists even at base flows. In addition bacteria monitoring should be done after hydro-flows to better document their effect. Nutrients are generally not elevated to levels of concern in the upper Winooski River. Nutrients (TP and TN) levels were not appreciably increased by the three village WWTF’s, with the exception of total nitrogen below the Cabot WWTF. Hydro-flows increased TP significantly however with average concentrations moderately elevated during hydro-flows. Turbidity was also elevated during hydro-flows indicating the elevated TP was mostly due to re-suspended streambed particulates (and the insoluble P that was mixed with the sediment in the streambed). The increase in turbidity was noticeable to the casual observer, but well below critical levels for aquatic life impact. Appendix 1: Results of Bacteria, and Turbidity samples collected in 2010. 2010 Bacti and Turbidity data for all sites. No dups or blanks included Site - RM Flow Bacti cfu /100mL Date Turbidity NTU JB 0.1 Base 93 6/22/2010 0.4 JB 0.1 Base 84 7/6/2010 0.9 JB 0.1 Base 178 7/20/2010 0.8 JB 0.1 High 2420 8/3/2010 9.8 JB0.1 Base 30 8/17/2010 0.4 JB 0.1 Base 33 9/7/2010 0.3 RES 01 NA 1 6/22/2010 0.9 RES 01 NA 1 7/6/2010 1.1 RES 01 NA 1 7/20/2010 1.2 RES 01 NA 19 8/3/2010 1.5 RES01 NA 1 8/17/2010 1.0 RES 01 NA 69 9/7/2010 0.8 WB 0.1 Base 84 7/20/2010 2.5 WB 0.1 High 2420 8/3/2010 3.1 WB 0.1 Base 59 8/17/2010 0.3 WIN 70.7 Base 387 6/22/2010 3.2 WIN 70.7 Base 291 7/6/2010 1.7 WIN 70.7 Base 365 7/20/2010 1.3 WIN 70.7 High 2420 8/3/2010 26.6 WIN 70.7 Base 142 8/17/2010 3.0 WIN 70.7 Base 236 9/7/2010 2.6 WIN 71.3 Base 548 6/22/2010 2.8 WIN 71.3 Base 365 7/6/2010 1.6 WIN 71.3 Base 236 7/20/2010 2.0 WIN 71.3 High 1730 8/3/2010 26.5 WIN 71.3 Base 135 8/17/2010 2.9 WIN 71.3 Base 192 9/7/2010 2.5 WIN 71.4 Base 488 6/22/2010 3.0 WIN 71.4 Base 649 7/6/2010 3.1 WIN 71.4 Base 261 7/20/2010 3.0 WIN 71.4 High 2420 8/3/2010 31.1 WIN 71.4 Base 219 8/17/2010 2.8 WIN 71.4 Base 387 9/7/2010 2.5 WIN 72.8 Base 193 6/22/2010 2.2 WIN 72.8 Base 579 7/6/2010 2.1 WIN 72.8 Base 205 7/20/2010 1.9 WIN 72.8 High 2020 8/3/2010 26.6 WIN 72.8 Base 105 8/17/2010 6.9 WIN 72.8 Base 46 9/7/2010 2.2 WIN 78.1 Base 222 6/22/2010 WIN 78.1 Base 199 7/6/2010 1.9 WIN 78.1 Base 579 7/20/2010 1.9 WIN 78.1 High 2020 8/3/2010 72.8 WIN 78.1 Base 125 8/17/2010 1.2 WIN 78.1 Base 1 9/7/2010 1.1 WIN 81.6 Base 185 6/22/2010 0.9 WIN 81.6 Base 219 7/6/2010 1.2 WIN 81.6 Base 378 7/20/2010 1.4 WIN 81.6 High 2419.6 8/3/2010 43.4 WIN 81.6 Base 96 8/17/2010 1.1 WIN 81.6 Base 51 9/7/2010 1.0 WIN 81.8 Base 210 6/22/2010 0.7 WIN 81.8 Base 206 7/6/2010 0.8 WIN 81.8 Base 411 7/20/2010 1.0 WIN 81.8 High 2419.6 8/3/2010 44.3 WIN 81.8 Base 156 8/17/2010 1.0 WIN 81.8 Base 76 9/7/2010 0.9 WIN 82.6 Base 214 6/22/2010 0.9 WIN 82.6 Base 548 6/22/2010 6.9 WIN 82.6 Base 236 7/6/2010 1.2 WIN 82.6 Base 548 7/20/2010 1.5 WIN 82.6 Hydro* 1120 7/20/2010 4.6 WIN 82.6 High 2419.6 8/3/2010 46.2 WIN 82.6 Base 261 8/17/2010 1.2 WIN 82.6 Base 102 9/7/2010 1.0 WIN 83.8 Base 166 6/22/2010 0.7 WIN 83.8 Base 114 7/6/2010 0.9 WIN 83.8 Base 201 7/20/2010 1.2 WIN 83.8 High 2419.6 8/3/2010 30.3 WIN 83.8 Base 108 8/17/2010 0.4 WIN 83.8 Base 83 9/7/2010 0.4 WIN 84.1 Base 219 6/22/2010 1.3 WIN 84.1 Base 139 7/6/2010 1.1 WIN 84.1 Base 162 7/20/2010 1.2 WIN 84.1 High 2419.6 8/3/2010 18.6 WIN 84.1 Base 48 8/17/2010 0.3 WIN 84.1 Base 96 9/7/2010 0.4 WIN 85.5 Base 24 6/22/2010 0.5 WIN 85.5 Base 82 7/6/2010 0.8 WIN 85.5 Base 108 7/20/2010 0.7 WIN 85.5 High 2419.6 8/3/2010 21.9 WIN 85.5 Base 21 8/17/2010 0.3 WIN 85.5 Base 81 9/7/2010 0.4 Appendix 2: Nutrient data summary from upper Winooski 2010 Flow L=low H=high, Flow Type B=Base, H=Hydro flow Site TN mg/l TP ug/l Turb NTU Date Flow Flow type NB 0.2 0.26 17.70 0.7 6/20/2010 L B NB 0.2 0.28 14.10 0.5 7/20/2010 L B NB 0.2 0.15 9.92 0.4 8/16/2010 L B mean 0.23 13.91 0.5 WIN 70.7 0.31 17.50 1.5 6/20/2010 L B WIN 70.7 0.31 15.60 1.2 7/20/2010 L B WIN 70.7 0.26 26.10 3.1 8/16/2010 L B mean 0.29 19.73 1.9 WIN 71.3 0.32 13.80 1.6 6/20/2010 L B WIN 71.3 0.33 15.30 2.0 7/20/2010 L B WIN 71.3 0.27 25.30 2.9 8/16/2010 L B mean 0.31 18.13 2.2 WIN 72.8 0.28 15.40 1.4 6/20/2010 L B WIN 72.8 0.30 15.20 2.2 7/20/2010 L B WIN 72.8 0.35 44.90 7.1 8/16/2010 L B mean 0.31 25.17 3.6 WIN 81.6 0.32 19.90 1.0 6/20/2010 L B WIN 81.6 0.39 17.40 1.4 7/20/2010 L B WIN 81.6 0.32 18.60 1.1 8/16/2010 L B mean 0.34 18.63 1.2 WIN 81.8 0.35 14.20 0.5 6/20/2010 L B WIN 81.8 0.40 11.30 0.9 7/20/2010 L B WIN 81.8 0.26 13.70 1.1 8/16/2010 L B mean 0.34 13.07 0.8 WIN 82.6 0.39 12.30 1.6 7/20/2010 L B WIN 82.6 0.41 20.20 4.5 7/20/2010 H H WIN 82.6 0.23 16.80 1.3 8/16/2010 L B mean (-hydro flow) 0.31 14.55 1.4 WIN 83.8 0.50 12.60 0.6 6/20/2010 L B WIN 83.8 0.44 12.90 1.3 7/20/2010 L B WIN 83.8 0.40 11.10 0.4 8/16/2010 L B mean 0.45 12.20 0.7 WIN 84.1 0.27 14.30 0.5 6/20/2010 L B WIN 84.1 0.29 12.60 1.2 7/20/2010 L B WIN 84.1 0.21 10.80 0.3 8/16/2010 L B mean 0.26 12.57 0.7 Figures 3-6 Sampling locations