Date of Award

2010

Document Type

Honors Thesis (Open Access)

Department

Colby College. Environmental Studies Program

Advisor(s)

F. Russell Cole

Second Advisor

David Firmage

Third Advisor

Philip Nyhus

Abstract

The purpose of this study was to assess the impacts of patterns of land use and development on water quality in the Belgrade Lakes on a regional scale. Regional research and cooperation could identify key areas in the watershed where development or changing land use could have the greatest negative influences on lake water quality. Past work has centered on water chemistry, nutrient dynamics, development and economic factors but there has been no comprehensive analysis of land use and development history for the entire Belgrade Lakes Region. The Belgrade Lakes are a chain of 7 lakes in central Maine connected by a complex system of streams and wetlands. Existing research on the Belgrade Lakes has focused on individual lakes and watersheds, but due to the interconnectivity of the system, limiting nutrients such as phosphorus (P) have the ability to be transported from one lake to another throughout the chain. The total phosphorus concentration in lakes is a particularly important water quality parameter because it can be a direct cause of algal blooms. Algal blooms threaten lake ecosystems and can result in dissolved oxygen depletion, fish kills, reduced water clarity, foul odors and declines in aquatic plants.

A Geographic Information System (GIS) was used to classify and quantify land use, identify spatial patterns of development and predict areas in the watershed most likely to be developed in the future. Analyses of current watershed development and projections for residential development in 2020, 2035 and 2050 were made using town records and demographic statistics. These projections were used to model the current phosphorus budget and the additional phosphorus load from future development. Cropland, residential lands and roads currently contribute a disproportionate 55% of the total external phosphorus load despite covering approximately 11% of the watershed land area.

Residential development is expected to increase by 1,327 units by 2050, which would increase the overall external phosphorus load into the lake system. Currently, approximately 1,811 kg P/yr are inputted to the Belgrade Lakes system from shoreline and non-shoreline residential development combined. By 2050, this could increase to 2,285 kg P/yr if mitigation procedures are not put into place. Moderate increases in total phosphorus concentrations of approximately 1 ppb are expected in Great Pond and Long Pond and relatively small increases are expected in East Pond and North Pond due to stagnating local populations in the Towns of Smithfield and Mercer. The largest projected increases are in Salmon Lake/McGrath Pond and Messalonskee Lake at approximately 2.3 ppb by 2050. These high expected changes can be attributed to the central location of the town of Belgrade among several of the lakes and its relative proximity to job centers such as Augusta and Waterville. The Town of Sidney is the fastest growing town in the region and is located directly between Augusta and Waterville, so future development in the Messalonskee Lake watershed will likely be the highest in the Belgrade Lakes watershed. Although some increases are more dramatic than others, all projected phosphorus concentrations are near or within the range necessary for algal blooms in Maine (1 2-1 5 ppb or higher), except Long Pond.

This study has implications for responsible land use management and development planning that could be combined with existing knowledge of nutrient dynamics to minimize phosphorus loading from future development and reduce loading from existing forms of development. Recommendations were included to assist local municipalities in improving lake water quality in the face of increasing development. Private dirt roads and residences are two areas where local property owners have the greatest ability to reduce phosphorus loading. Routine road maintenance and shore line buffers consisting of native vegetation are two relatively simple methods of reducing areas of exposed soil and erosion that lead to phosphorus loading. Towns should develop plans to update grandfathered septic systems, especially along the shoreline, to reduce phosphorus loading from existing sources. Additional research is also necessary to examine the regional effects of development in one part of the Belgrade Lakes watershed on another.

Keywords

land use, water quality, Maine

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