Grovers Mill Pond
The neighborhood I live in has a special claim to fame as the place in which Martians landed in Orson Welles' famous radio broadcast War of the Worlds. As our local newspaper put it, "Thanks to Orson Welles, Grovers Mill may be the most famous neighborhood in all of central New Jersey" ( Trenton Times, May 9, 2004). Grovers Mill Pond and Big Bear Brook make up the watershed that greeted these strange visitors. In the 1800s early settlers to the area built a 400-foot-long earthen dam to trap Big Bear Brook for their grinding mill. Over the years, silt and sediment have spilled into the pond from nearby farms, creating an over-vegetated ecosystem resembling thick green muck (McCrone, 2004). This eutrophication has greatly reduced the amount of dissolved oxygen available to the aquatic organisms in the pond (Greenwood et al, 356). In addition, the dam has become hazardous, with hundreds of trees growing from its earth foundation. This past summer the rehabilitation of Grovers Mill Pond and Dam got underway. Thus far, the pond has been drained but not yet dredged, trees and shrubs have been removed, and efforts are presently underway to reconstruct the old earthen dam.
Insofar as Grovers Mill Pond flows into Big Bear Brook at my study site, I wondered what impact the reconstruction might have on Big Bear Brook.
Big Bear Brook
Walking along Big Bear Brook, one sees an idyllic scene of lush vegetation that includes ferns, vines, and a velvet carpet of green moss. The area is rich in trees, including evergreens, maple, and oak. The brook runs through a forested wetland with random expanses of surface water and mushrooms sprouting in the damp soil. Among the wildlife enjoying the landscape are a resident great blue heron, squirrels, mallards, white-tailed deer, a variety of birds, and dragonflies. Looking into the one-foot-deep brook, one sees leaves, stones, and duckweed.
Litter in Big Bear Brook
Sadly, upon closer inspection there is evidence of pesky "litterbugs." Litter in the form of candy wrappers, empty soda and beer cans, yogurt containers and even a tire, mars the landscape. The general area smells mildly of decay. I believe the odor is caused by decaying plants because I didn't see visible evidence of sewage or waste from agricultural or domestic uses. There are homes near the brook, but no septic tanks.
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Along the banks of the brook is a good deal of moss and a small amount of sedge. The vegetation thickens as one walks away from the pond, further along the brook. McCormack, in her interesting book, Vanishing Wetlands, explains that if wetlands are not overburdened with effluence they can act as pollution filter systems for groundwater and streams (McCormack, 1995, p. 46). Lisowski and Williams elaborate: "Wetland plants can absorb and break down impurities, preventing pollutants from contaminating water. In addition, the roots and stems of wetland plants retain silt and sediment, preventing pollutants from traveling farther downstream" (Lisowski and Williams, 1997, pp. 14-15). I wondered what role this wetland plays in the water quality of Big Bear Brook as it travels downstream. I hypothesized that as the water traveled down Big Bear Brook, away from Grovers Mill Pond, the increasing vegetation along the banks would purify the water and indicators of water quality would change positively.
Reconstruction at study site
I decided to collect water samples at five different points along the brook and do a variety of tests to learn more about the quality of the water. As
Greenwood, Allan, and Shepard note, "There is no single measure to objectively describe the quality of a stream... Rather, it is defined in terms of
various chemical, physical, and biological characteristics. Together, these factors define the 'health' of the aquatic ecosystem..." (Greenwood
et al, 2004, p. 358). I tested for benthic macroinvertebrates, total coliform bacteria, dissolved oxygen, nitrates, pH, phosphates, temperature, and
turbidity, using the LaMotte Green Water Monitoring Kit. In addition, I contacted Steven E. Yergeau, restoration specialist at the Stony Brook-Millstone
Watershed Association, who was kind enough to send me raw data collected since the 1990s on Big Bear Brook. This data would serve as a basis for
comparison with my findings to see how the restoration project at Grovers Mill Pond and Dam might be impacting the brook. The raw data from the previous
year would be my control. I hypothesized that in the short term the restoration project would negatively impact the quality of water in Big Bear Brook
because of the potential stresses that can be experienced during reconstruction. Because the quality of any aquatic habitat is the product of the chemical, biological, and physical conditions of a stream and its watershed, if the hydrology of the watershed is disrupted, it can result in changed concentrations of suspended solids or biostimulatory nutrients such as nitrogen or phosphorus, potentially affecting aquatic life (United States Department of the Interior, Fish and Wildlife Service, 1988 and California Environmental Protection Agency, 2004). Over the long term, I hypothesized that Big Bear Brook would benefit from the rehabilitation of Grovers Mill Pond and Dam because it is expected that the water quality of Grovers Mill Pond will be greatly improved (Snedeker, 2004).
Map of water sampling sites (Click to enlarge)
I gathered the following data from Big Bear Brook in October of this year. I chose to demarcate my study site as the watershed area bounded by
Grovers Mill Pond and Mercer County Bridge No. 762.1. I took water samples from the five sites identified in the diagram, as drawn in my field
journal. ( See appendix on page 3 for sampling procedures.)
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