02-10-1997 Council Packet - Laserfiche WebLink

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the total l^eldahl nitrogen concentration. This suggests that 35 percent of the nutrients leaving the golf courses are in a particulate form. This was unexpected because loss of soil under well established turf is typically very low. However, visual inspection revealed the presence of grass clippings in most of the samples. The majority of the suspended material appears to be from grass clippings caused by the frequent mowing of the courses. Management practices which prevent the movement of the clipping off of the courses, or remove them from the runoff stream would reduce the export of nutrients from golf courses. The mean parameter concentrations at each of the sample sites are shown in Table 7. Interquartile boxplots showing the median and range for each of the parameters are shown in Appendix B. Differences between the sites for each parameter were determined by ANOVA procedures performed on the normal log of the concentrations because, although the means were normally distributed, they did not have equal variances. Significant differences (p<0.05) between site means for the different parameters are shown in Table 8. For most of the nutrient parameters, the mean concentrations at the Minikahda inlet and outlet sites were significantly lower than at the other sites, and the mean concentrations at the Meadowbrook site were higher (Table 8). The mean total phosphorus concentrations at the Minikahda sites was not significantly different from the Woodhill Country Club. The concentrations of most parameters at Baker National and the Woodhill Country Club were not significantly different. The common perception that the more intensively manicured private courses would have higher pollutant export concentrations is not supported by the data. The data also show that under proper management, high quality turf can be maintained with minimal effect on runoff water quality. No significant differences were found for any parameters between the Minikahda inlet and outlet sites, showing that the golf course did not significantly increase nutrient concentrations in the stream flow. The Minikahda golf course, therefore, appears to have no negative effect on the water quality of Lake Calhoun, which is immediately downstream of the course. FUNGICIDES AND HERBICIDES Detectable concentrations of at least one fungicide were observed in 40 of 59 • unoff water samples. Chlorothalonil, (Trade Name DACONIL), the most frequently observed fungicide, (Figure 3), was detected in 34 samples. DACONIL® was also the most frequently applied fungicide. Propiconazole (BANNER®) was detected in 14 samples, end Iprodione (CHIPCO®) in 4 samples. Both Chlorothalonil and Propiconazole were detected in the same sample on 12 occasions, and Chloroth''’onil and Iprodione were both detected in 3 samples. Pentachloronitrobenzene (PCNb) was not detected in 4 • (