Potentially Damaging Effects of The Wilder Dam on the Connecticut River's Ecosystem

I was informed about NHAS, and by extension AJAS, by a good friend. I had been looking for a scientific opportunity for a while beforehand, and I was excited to have the chance to step into the world of science. I found I had a great passion for research and discovery, and it carried me through a summer lockdown that I spent testing and researching. After the summer session ended, I continued to refine my paper and presentation in preparation to present at AJAS. While my research focuses on modern-day ecology and environmental science, the bulk of my passion lies with prehistoric life. I'd like to have a career in paleoecology someday, as a teacher or a researcher.

The Effect of The Wilder Dam on the Health of the Connecticut River

Kai Doron

Hanover High School

ABSTRACT

Dams, such as the Wilder Dam on the Connecticut River, often have negative effects on the waters around them. Dams can cause stagnation and temperature fluctuation, leading to eutrophication and a higher level of fecal contamination. The aforementioned factors could have a large effect on the health of the Connecticut River and the surrounding area as a whole. To investigate the quality of the water above, at, and below the Wilder Dam, dissolved oxygen, ammonia, phosphate, microplastics, and total dissolved solids concentrations, temperature, pH, and total coliform counts were monitored over the course of three days in July 2020. Water was collected via a bucket and distributed across colorimetric tests and endo agar bacteria plates. The data collected indicates that the Wilder Dam increases the water temperature by an average of 1 ℃ before it flows downstream, and causes a spike in coliform growth by at least 250 CFU/ 100mL. The Wilder Dam appeared to have no consistent impact on the other test parameters, though it is possible one may have emerged with increased testing. The changes seen indicate that the Wilder Dam could be damaging the surrounding ecosystem by harming aquatic fauna through fluctuating temperature and fecal contamination and reduce space on the banks through flooding, which would lead to the harm of terrestrial life.

INTRODUCTION

Dams often directly affect surrounding ecosystems by disrupting the natural environment.1 Dams can instigate changes that can cause adverse effects such as stagnation, temperature fluctuation and flooding. Stagnation is caused when a large body of water is made still rather than moving, and can lead to increased  bacterial growth and an increase in the overall temperature of the water column.1 Temperature increase can in turn make the area uninhabitable for many species of aquatic life. It can also cause increased levels of dissolved oxygen, which can indicate algal blooms, phosphate and ammonia. These chemicals can indicate fecal pollution.² Temperature increase can also cause trash to break down into microplastics.³ Flooding, caused by the construction of a dam, greatly reduces liveable area for riverside animals and plants.

The Wilder Dam is located on the Connecticut River and spans the border between the states of New Hampshire and Vermont and consists of a dam with two banks totaling 580 feet.1  The dam was constructed by Great River Hydro to generate power and provides a popular fishing spot in the form of Wilder reservoir. This investigation looked at the impacts of the Wilder Dam on the temperature of the Connecticut River, the concentrations of dissolved oxygen, ammonia, phosphate, total dissolved solids, the size and concentration of microplastic particles, and the levels of coliform bacteria. This research is important because the Wilder Dam may be a detriment to the Connecticut River, and no recent readings have been taken due to the current pandemic.

MATERIALS

Colorimetric dissolved oxygen, ammonia, and phosphate tests purchased from Chemetrics were all used according to the procedures detailed by the supplier. pH strips were also used according to instructions. A microplastic sieve set (355?m, 135?m, and 75?m,) was used to segregate microplastics by size.  A dissection microscope was used to sort microplastics from non-plastics and suspected microplastics were confirmed by poking with a hot dissection needle. A bacterial incubator was used to culture coliform plates. Endo Agar plates were used to culture coliform bacteria. Pipettes, syringes, and disposable gloves were used for the collection of samples. A TDS (total dissolved solids) meter was used to measure TDS and temperature.

Figure 1: A map of the testing site locations in relation to each other and the flow of the Connecticut River. Ledyard was upstream of the Wilder Dam at Ledyard Bridge, Wilder is located at the Wilder Dam itself, and Lyman is downstream from the Wilder Dam at Lyman Bridge.

METHODS

Testing on location

Water samples were obtained according to the protocols outlined by the New Hampshire Department of Environmental Services Volunteer River Assessment Program.7  A TDS (Total dissolved solids) meter was used to measure the TDS concentration and temperature of the sample. The remaining collected sample water was stored for later microplastics testing. Colorimetric tests were used to measure the concentration of phosphate, dissolved oxygen, and ammonia. Each of these tests were repeated three times on site.

Testing Coliform

On location, 1.5 mL of sample water were pipetted into a petri dish with endo agar, which selectively grows total coliforms, and sealed for transportation. Endo agar also allows for the specific identification of E. coli bacteria as that bacteria forms shiny, metallic green colonies on the plate surface. The coliform plates were unsealed and dried for 12-24 hours to fully absorb the sample. The samples were then placed in an incubator set to 37℃ and allowed to incubate for 48 hours after drying. Promega Colony Counter was used to take 3 pictures of each plate and the results were averaged.4

Testing Microplastics

To collect microplastics, 500 mL of sample water were poured through the sieves to sort the microplastics by size (355?m, 0.135?m, and 0.075?m). Suspected microplastics were poked with a heated needle under a microscope to test if they melted, which would confirm them as plastics. The plastics were weighed by size range and the concentration of each size of microplastics was calculated.

RESULTS

Figure 2: The temperature of the water in Celsius at each of the three testing sites on each day of testing. From left to right, the bars in each set represent the Ledyard, Wilder, and Lyman sites. The water was consistently one degree Celsius or more warmer at the downstream locations than at the upstream sampling location, even when the sampling time was changed. The temperatures across all sampling events stayed in the range of 23-27 degrees.

Fig. 2: The concentration of total dissolved solids at each of the three locations on two days of sampling. (Only two days of testing could be performed due to malfunctions with the meter.) From left to right, the bars in each set represent the Ledyard, Wilder, and Lyman sites.

Figure 3: The pH of the Connecticut River at each of the three testing locations on each day of testing. Red lines indicate a healthy range of pH. From left to right, the bars averages in each set represent the Ledyard, Wilder, and Lyman sites. The error bars represent standard deviation across three test strips.

Figure 4: The ammonia concentration in parts per million at each of the three testing locations on each day of testing. From left to right, the bars in each set represent the average at Ledyard, Wilder, and Lyman sites. The bars represent the mean from each of the three tests taking on each day at each location with error bars showing standard deviation.

Figure 5: The phosphate concentration in parts per million at each of the three testing locations on each of the three days of sampling. From left to right, the bars in each set represent the average at Ledyard, Wilder, and Lyman sites. The bars represent the mean from each of the three tests taking on each day at each location with error bars showing standard deviation.

Figure 6: The dissolved oxygen concentration in parts per million at each of the three testing locations on each of the three sampling days. The bars represent the mean from each of the three tests taking on each day at each location with error bars showing standard deviation. From left to right, the bars in each set represent the Ledyard, Wilder, and Lyman sites.

Figure 7: The total coliform counts, presented as colony forming units (CFU) per 100mL of water, of the samples taken from each of the three testing sites on each of the three days of sampling. The sample gathered on July 1 at the Lyman site had 4 colonies of E. coli evidenced by the presence of green metallic colonies on the endo agar plate. The presence of E. coli on this day is indicated in the graph. The bars represent the mean from each of the three coliform pictures averaged for the three plates for each site.  Error bars show standard deviation. From left to right, the bars in each set represent the Ledyard, Wilder, and Lyman sites.

Figure 8: The mean concentration of microplastic particles in the water at each of the three sample sites for 3 days. The bars represent the mean from each of the three tests at each site, with error bars showing standard deviation. From left to right, the bars in each set represent the Ledyard, Wilder, and Lyman sites.

DISCUSSION

Phosphate readings were within the range of 0 to 10, with no discernable pattern across testing locations or days. The mean reading was 0.15. Ammonia readings were consistently between 0 and 0.25 with no discernable pattern. There was no pattern present with dissolved oxygen readings with readings in the range of 4 to 7. Smaller microplastics were more consistently found at and downstream of the dam, while larger plastics were more evenly spread throughout testing locations. The total coliform colony count was higher at and downstream of the dam when compared to upstream. E. coli was found at the Lyman site on July 1st with 4 colonies. The TDS readings were in the range of 63-69 ppm, with no particular pattern to the readings.

All readings were in the range of normal, healthy levels at all locations. As can be seen in Figure 2,  the water temperature was found consistently warmer at and below the dam. This suggests the water there may be stagnant.6 This could be the cause of the increased bacterial growth from the samples taken at and below the dam.2 However, water flow measurements need to be taken in order to confirm stagnation is indeed present and if it may be a cause of the temperature increase and elevated total coliform levels at and below the dam.  This bacterial growth, and particularly the presence of E. coli, suggests possible fecal contamination in the water downstream of Wilder Dam, and stagnant water could increase the impact of fecal pollution.

I believe the simplest, although not the easiest or cheapest solution to mitigate fecal pollution would be to destroy the dam. However, I believe that the next best option is to create a filtered stream around the dam that decontaminates the released water at least somewhat before it goes downstream. These solutions could help the overall health of the river, and reduce the impact of the Wilder Dam on the safety of the Connecticut River. However, there is still not enough evidence to take action yet. In the future, the best path to take would be testing a wider area and also testing for water flow speed as well as coordinating with others to test more areas at the same time across more testing days/seasons, and wait for similar conditions to test more accurately.

REFERENCES

Water, Water Everywhere. HACH Company. Second Edition. 1983.

“Wilder Project FERC No. 1892.” Great River Hydro LLC Relicensing, www.greatriverhydro-relicensing.com/wilder-project/.

“Home.” Hanover Conservancy, www.hanoverconservancy.org/lands/wilder-dam/.

Andrea D. Steffen. “Report: People Eat, Drink, And Inhale Teaspoon Of Microplastics Every Week.” Intelligent Living, 13 June 2019, www.intelligentliving.co/eat-drink-inhale-microplastics/.

“Home.” Calculators Tools, www.promega.com/resources/tools/.

"Beyond Three Gorges in China". Water Power Magazine. January 10, 2007. Archived from the original on June 14, 2011. Retrieved November 23, 2010.

https://www.des.nh.gov/organization/divisions/water/wmb/vrap/documents/vrap-protocols.pdf