Defining reference conditions for measuring the effects of shoreline development on lakes in Maine

Kirsten Ness

Lakes in Maine are valuable ecologically, economically, and recreationally.  Shoreland zoning regulations were instituted in 1971 by the State of Maine to control development and alterations of lake riparian zones. These regulations must be observed by towns to control activities within 250 feet of the high water marks of lakes and ponds larger than 10 acres. The amount of protection provided by these zoning regulations has not been evaluated, largely due to a lack of definition of reference conditions for lake littoral zones. The focus of our study is to describe and evaluate factors at the watershed, lake, and site scales that influence the structural complexity of the littoral zone. Important factors at the watershed scale include lake position in the watershed, geologic setting, and land use patterns. The intensity of shoreline development, hydrology, morphometry, and water chemistry parameters influence littoral habitats at the lake level.  Site level factors include aspect, riparian vegetative cover, slope of the riparian zone, and lake fetch. Based on these factors we can develop expectations for habitat complexity measured by coarse woody habitat, macrophyte functional type, and sediment composition. We also plan to explore using macrophyte species composition as a biotic indicator of disruption of littoral habitats by shoreline disturbance. This pilot study focuses on small to moderate size, headwater drainage lakes with little or no shoreline development in an area of uniform geology. Results will be used to develop habitat and biotic metrics to apply to lakes representing a gradient of development intensity.