“A river is the report card for its watershed.”- Alan Levere, CT DEP
Throughout history, people have been drawn to rivers for their beauty, fertility, and vast potential for recreational and technological uses. In many instances, humans have abused rivers and other bodies of water to the point of permanently changing or damaging their ecosystems. Legislation and regulation has been employed to remediate and prevent the worst cases of abuse. However, pollution has not been totally eradicated from our watersheds.
Fishkill Creek is one of many tributaries in the Lower Hudson River Basin, the most heavily impaired segment of the Hudson River in terms of water quality. By studying tributaries like Fishkill Creek, we cannot only study isolated pollution input, but also better relate these inputs to the health of major river basins.
A Brief Overview and Analysis of the Data Trends
We performed several water-sampling tests at ten sites along Fishkill Creek. We tested for Escherichia coli, dissolved oxygen, pH, turbidity, nitrate, electrical conductivity, and temperature. Our study reveals much about the health of the Kill and its surrounding ecosystem.
The highest level of E. coli, for instance, was observed at Site 7 and was found to be 220 CFU/100 mL; the EPA regulations for E. coli concentrations in water designated for recreational uses is 410 CFU/100mL for a one-time measurement. Even at its highest, E. coli concentrations were below accepted regulatory standards. However, the concentration of E. coli in the water dissipated as we moved closer to the source of the creek, suggesting that various human activities that took place as the creek progressed were responsible for the microbes.
For the water temperature we encountered, saturation of dissolved oxygen was expected to be 9.2 mg/L to 10.2 mg/L. Most of the readings taken at Fishkill Creek were slightly below this, and lowest at Site 5, with a reading of 7.06 mg/L. However, as Site 5 was a relatively lentic and marshy stretch of the river, this is to be expected (slow-moving or sedentary water bodies have lower levels of dissolved oxygen). Dissolved oxygen peaked at Site 1, (9.34 mg/L) where water was taken immediately after being aerated by a waterfall; this is also to be expected.
The pH of the river was mostly constant, if slightly alkaline, and this can likely be attributed to minerals dissolved in the water. The Fishkill Watershed has limestone deposits, which would contribute to a higher pH.
Turbidity is a measurement of suspended solid particles. When the creekmoved quickly, it was capable of carrying a greater quantity of particulate matter, and consequently, the turbidity was higher. When the water slowed, suspended solids settled to the bottom. The sites we surveyed ranged greatly in regards to the speed and energy of the water; our turbidity readings fluctuated accordingly. Lentic sites (such as 1, 3, 5, 7, and 10) had lower turbidity readings (3 NTU to 3.5 NTU) than lotic sites including 4, 6, and 9 (5.0 NTU to 5.9 NTU).
Nitrate also decreased as we neared the source of the creek. Again, this is to be expected, as nitrogen is often used as a fertilizer, and its presence in the water was likely the result of fertilizers being used upstream. EPA guidelines state that nitrate levels may not exceed 10 mg/L; the greatest concentration (site 5) in the Fishkill Creek was only 2.4 mg/L.
Electrical conductivity, the ability of water to conduct an electrical current, is used as a method to determine the quantities of anions and cations from dissolved ionic compounds in the water. The Fishkill Creek feeds into the Hudson River Estuary, which mixes saltwater into the otherwise-freshwater creek during high tides near its confluence. The electrical conductivity generally decreased as we moved upstream, away from the Hudson. However, a spike at site five indicates possible pollution from road salt runoff.
We found that E. coli, nitrate, and electrical conductivity increased with the flow of the creek downstream, likely due to human influences. Turbidity and dissolved oxygen fluctuated in accordance with river speed. While we are somewhat concerned about Sites 5 and 7, where we found rather high levels of E. coli and nitrate, and rather low levels of dissolved oxygen, Fishkill Creek as a whole appears to be in excellent condition. All levels of potential toxins are far below EPA standards. In addition, the ecosystem in and around the creek is thriving, as we observed snakes, fish, and crawfish at Site 10. As a whole, our studies show that Fishkill Creek is in relatively good shape, and is likely not detrimental to the overall quality of the Hudson. With careful monitoring of tributaries like the Fishkill, we can address issues like water pollution on a smaller, more manageable scale. In time, we will develop an increased understanding of the dynamic Hudson River Basin.