MAPPING OF SUBMERGED SHORELINES AT JUNIUS PONDS, NY

Abstract

Wetland hydrology can be complex with changes in water budgets and routing, which can influence sensitive ecosystems containing rare plant and animal species that rely on stable or slowly changing water levels. Junius Ponds, Unique Area, NY consists of four interconnected ponds which were formed in kame deposits associated with the last glaciation. Water flows from south to north from Phillips Pond to Lowery Pond and into East and West Newton Ponds. In some locations along the margins of the ponds, there are fens containing rare endemic species. Water levels in these ponds are pivotal because they control the amount of rare fen habitat available. Rising water levels submerge and remove habitat. Over the last ~100 years, pond water levels have generally risen and today are near their highest in historical time. Water levels and water routing are governed by culverts associated with I-90 and SR 318, changes in land use, and are also influenced by factors like beavers and climate. Here, we use a combination of historical aerial imagery, bathymetric mapping, and side scan sonar to investigate the modern high stand shoreline and prior submerged shorelines. This information provides constraints on past wetland extents and associated water level changes. The sonar data was collected with a Humminbird SOLIX 12 CHIRP MEGA SI + G2 with frequencies of 50/83/200/455/800 kHz & 1.2 MHHz in the summer of 2018. Reefmaster, SonarTRX, ArcGIS, and Google Earth were utilized in the analysis of sonar data and generating detailed bathymetry. Comparing depth and speed corrected side scan sonar data with aerial imagery indicates that, past shoreline features in Lowery Pond are approximately 1-1.5 meters below the pond surface level. There are also several generations of shoreline features indicating multiple lake level stages. These data are foundational for examining the evolution of wetland systems through time and for site management.