Data sheets:
Water Quality Index: As mentioned in the introduction, the WQI for the river as a whole was 74.9%. On the WQI ratings scale, this percentage falls under the category of "good". This number was obtained from nine of the ten tests previously discussed (benthic macroinvertebrates is not a factor in this calculation). Once all data had been collected, each test was analyzed independently. The data from each test was entered into a chemical monitoring data sheet, where it was assigned a Q-Value. Q-Values are found on a scale of 1-100, with 1 being the worst and 100 being the best possible value. The Q-Values for each test were then multiplied by a weighting factor, which varied depending on the importance of each test. The resulting values from each test were then added together to obtain the water quality index.
Low scores: Despite the good overall WQI, low scores were calculated for the individual tests of turbidity, BOD, and E. Coli bacteria. For turbidity, the low water levels at the time of testing increased the concentration of suspended solids. Also, the very fine particles that existed on the substrate of the river were easily kicked up or dislodged. These two factors resulted in a high turbidity, which translates into a low Q-Value for this test. The significance of a low score for turbidity is that the temperature of the water goes up, and the water's capacity for dissolved oxygen goes down. For BOD, a low score implies that the amount of oxygen needed by aerobic organisms is high. This indicates a high presence of decomposers, which break down organic matter. Therefore, a large amount of organic matter in the river could be the reason for the low BOD score. As for E. Coli bacteria, the low water level of the river is again the likely reason for the low score. The low water level increases the concentration of the fecal coliform that is present, so a water sample will have more fecal coliform than it would have if the water level had been at normal levels.
Health of the river: The good water quality ratings that resulted from both the WQI and PTI calculations implies that the river is very healthy. However, some of the individual tests that produced low scores, as listed above, show that there is still room for improvement. One way to improve the river's health would be to increase the water level of the river. This could be done by reducing the amount of water extracted or diverted from the river. Another way to improve the river's health would be by decreasing the amount of organic matter/waste that is introduced into the water. This could be done by making sure that no domestic animals use the river for excretion, and by prohibiting the deposit of any animal carcasses and/or waste by humans into the river. To continue the existing quality, it is important to keep the watershed mostly free of human alteration. The protected forest preserve that surrounds the river is a major reason for the high water quality.
Discrepancies between tests: While the PTI rating obtained from the benthic macroinvertebrate data was excellent, the WQI rating achieved by the nine chemical tests was only good, failing to reach the level of excellent. One possible reason for this discrepancy is that a WQI rating is more sensitive to daily weather and the influx of runoff. Many of the chemical tests are greatly affected by qualities of the river that can change frequently, such as the river's water level. Therefore, a study conducted on a day like ours that followed a short period of no rain can impact the results of many of the tests in a negative way. On the other hand, benthic macroinvertebrates must survive in the water constantly, and are not impacted by the frequent changes (like daily weather). Therefore, the PTI rating is not as influenced by daily changes as the WQI rating is.
Limitations of our study: One major limitation to our study is the fact that all tests were based on a small sample of a much bigger river. With a sample size this small, it is possible that the average results of the entire river could be significantly different. Another limitation is the fact that our tests were only taken on one day (three days when the other two classes' data is taken into account). As stated above, daily changes in weather and other factors mean that results may be quite different from one day to the next.
Suggestions for further study/improvements: If this study were conducted again, I would recommend recording data on more than just three days. Taking data for more days improves the accuracy of study because it gives a better idea of how the river quality is on an average day. If possible, I would also recommend conducting the same tests both upstream and downstream from the main location. This would provide useful information on how the water quality is changing (if at all) as you move along the river. This further study would allow more conclusions to be drawn about what in the watershed is changing the quality of the water.
Low scores: Despite the good overall WQI, low scores were calculated for the individual tests of turbidity, BOD, and E. Coli bacteria. For turbidity, the low water levels at the time of testing increased the concentration of suspended solids. Also, the very fine particles that existed on the substrate of the river were easily kicked up or dislodged. These two factors resulted in a high turbidity, which translates into a low Q-Value for this test. The significance of a low score for turbidity is that the temperature of the water goes up, and the water's capacity for dissolved oxygen goes down. For BOD, a low score implies that the amount of oxygen needed by aerobic organisms is high. This indicates a high presence of decomposers, which break down organic matter. Therefore, a large amount of organic matter in the river could be the reason for the low BOD score. As for E. Coli bacteria, the low water level of the river is again the likely reason for the low score. The low water level increases the concentration of the fecal coliform that is present, so a water sample will have more fecal coliform than it would have if the water level had been at normal levels.
Health of the river: The good water quality ratings that resulted from both the WQI and PTI calculations implies that the river is very healthy. However, some of the individual tests that produced low scores, as listed above, show that there is still room for improvement. One way to improve the river's health would be to increase the water level of the river. This could be done by reducing the amount of water extracted or diverted from the river. Another way to improve the river's health would be by decreasing the amount of organic matter/waste that is introduced into the water. This could be done by making sure that no domestic animals use the river for excretion, and by prohibiting the deposit of any animal carcasses and/or waste by humans into the river. To continue the existing quality, it is important to keep the watershed mostly free of human alteration. The protected forest preserve that surrounds the river is a major reason for the high water quality.
Discrepancies between tests: While the PTI rating obtained from the benthic macroinvertebrate data was excellent, the WQI rating achieved by the nine chemical tests was only good, failing to reach the level of excellent. One possible reason for this discrepancy is that a WQI rating is more sensitive to daily weather and the influx of runoff. Many of the chemical tests are greatly affected by qualities of the river that can change frequently, such as the river's water level. Therefore, a study conducted on a day like ours that followed a short period of no rain can impact the results of many of the tests in a negative way. On the other hand, benthic macroinvertebrates must survive in the water constantly, and are not impacted by the frequent changes (like daily weather). Therefore, the PTI rating is not as influenced by daily changes as the WQI rating is.
Limitations of our study: One major limitation to our study is the fact that all tests were based on a small sample of a much bigger river. With a sample size this small, it is possible that the average results of the entire river could be significantly different. Another limitation is the fact that our tests were only taken on one day (three days when the other two classes' data is taken into account). As stated above, daily changes in weather and other factors mean that results may be quite different from one day to the next.
Suggestions for further study/improvements: If this study were conducted again, I would recommend recording data on more than just three days. Taking data for more days improves the accuracy of study because it gives a better idea of how the river quality is on an average day. If possible, I would also recommend conducting the same tests both upstream and downstream from the main location. This would provide useful information on how the water quality is changing (if at all) as you move along the river. This further study would allow more conclusions to be drawn about what in the watershed is changing the quality of the water.