A Brief Historical Ecology of the Spring Valley Pond
The Spring Valley pond is a small, man-made pond located in Carrboro, North Carolina. It is part of the Bolin Creek watershed, which drains northern Carrboro and eventually reaches Jordan Lake. It was built as part of the development of the Spring Valley subdivision during the mid 1980s, and accounts for a substantial portion of the neighborhood greenspace. The aesthetic and biological characteristics of the pond are determined in large part by a constantly evolving interplay of natural and human influences.
This website explores the pond in a historical context in order to
better understand how the combination of and reaction between natural processes
and human activities have changed the pond over time,
with the expectation that a detailed understanding of the pond will allow Spring Valley residents
(and anyone else interested) to create the best possible community space.
Currently, this exploration focuses on the relationship between the faunal community of the pond and the aesthetic expectations of neighborhood residents. Other threads of exploration which this project may follow in the future include a floral inventory, a more detailed limnilogical assessment, and a collection of resident comments, memories, and expectations. More about Historical Ecology and the perspective of this project can be found here.
Prior to the the construction of the Spring Valley development, the land was essentially unused. This image, from the Town of Carrboro archive of aerial photographs, shows the site in February, 1979 with an approximate map of current roads are overlaid in blue. Numerous small streams drain the land, feeding Bolin Creek, which appears as a brown band cutting across the upper right-hand corner of the image.
The Spring Valley subdivision was developed by Illinois-based Prairie Development Inc,
who purchased the 34 acre tract on which it is located in early 1984.
The sale contract can be viewed here.
Based on the recommendations of civil engineers, plans were made to construct a dam between property and Bolin Creek,
collecting the output of the small streams in a small reservoir.
The dam and reservoir are discussed during this
Carrboro Board of Alderman meeting February 28, 1984.
The likely motivation in building the pond was to collect runoff from the neighborhood,
allowing the developers to include a greater percentage of impermeable surface area (such as roads and houses).
Construction of the pond had begun by 1985, when the Town of Carrboro produced the aerial photograph show at left.
During the first five to ten years of the pond, from its construction through the early 1990s, native flora and fauna which colonized the new habitat from the surrounding woodlands and nearby Bolin Creek played a large role in shaping the pond's appearance and defining the pond for residents.
of the young pond's most common and easily observed species included Red-winged Blackbirds,
Great Blue Herons, Copperheads, Bullfrogs, American and Fowler's Toads, Cattails, and Water Lilies.
Please see the faunal inventory for further discussion.
This assemblage of species gave the pond a somewhat swamp-like appearance, similar to a beaver pond, with high biotic productivity and a large proportion of cryptic, weedy habitat along the pond margins (see the picture at right). This habitat came to be associated with perceived and potential declines in pond quality by some residents, specifically due to silt accumulation in areas of dense plant cover (especially at the shallow inlets), and as cover for undesirable animals (especially snakes). Neighborhood opinion on these issues is made especially clear in the minutes of a May, 1989 home owner's meeting addressing the pond (see pages 1, 2, 3, and 4)
Another issue discussed in the 1989 minutes, and regularly during the early years of the pond, is water color and quality. Eutrophication and turbidity have major effects on pond aesthetic, and a muddy pond with prominent algal growth was seen as a problem. Continued development upstream of the pond resulted in a prominent suspended accumulation of the orange clay characteristic of the area, as seen in these photos (here and here) from September, 1993. Residents responded to these issues in part by adding a colorant to the pond's water and introducing Grass Carp, a Eurasion fish widely used for aquatic weed control. More on Grass Carp can be found on the faunal inventory page. A September, 1994 report from the pond management consultant Aquaculture Advisory Service provides further details on modifications made by the residents to the pond's water and plant and animal communities. (see pages 1, 2, 3, and 4)
The image at left is from 1995, and shows some of the results of the decisions discussed above, as does
another image from the same year.
The pond is essentially clear of marginal vegetation, except for ornamental trees and woody shrubs,
and water color is distinctly different.
Alongside efforts to modify the plant community and water quality, which appear to have been driven largely by the aesthetic expectations of Spring Valley residents, major changes to the faunal community were made.
Management of pond fauna falls into two general categories: efforts to resist colonization of the pond by native species of plant and animal (such as beaver, muskcrat, and the vegetation discussed above), and the introduction of animals (primarily fish), often with the expressed goal of displacing less desirable members of the biotic assemblage. By bolstering pond ichthyofauna through stocking, residents hoped to reduce the population densities and overall species richness of reptiles and amphibians in the pond. A second report by pond management contractors, dated January of 1997, details the stocking of several fish species. The report also discusses the control or removal of several native species, selectively including and excluding species from the pond.
More recently, Spring Valley residents decided to remove the domestic Muscovy ducks, one of the longest-standing, most prominent, and most contentious members of the pond's avifaunal community. Their removal has been an issue practically since they were introduced, with debate revived annually by the appearance a new generation of ducklings, seen here. Details of the final decision and relocation of the ducks can be found in this selection from a 2005 neighborhood newsletter. The absence of these larger, more aggressive domestic ducks may be the reason wild mallards appear to becoming more regular visitors to the pond.
Furthermore, cattails have recolonized one inlet of the pond. If allowed to persist, other, previous members of the pond community (such as Red-winged Blackbirds) may also return. These developments may be indicative of a return to a less modified biotic and aesthetic state, driven (or allowed) by changes in neighborhood opinions and expectations.
All content is © Jeff Mette 2006 unless otherwise noted.
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