Dynamic temporal patterns of nearshore seepage flux in a headwater Adirondack lake

Although seepage in lakes is known to vary as a function of precipitation and watershed characteristics, temporal patterns of seepage flux over daily and weekly time scales have not been extensively studied with a concentrated effort of direct measurement of seepage in nearshore areas. In this study, seepage was intensively measured with seepage meters over two summers and during snowmelt in Lower Sylvan Pond, a small lake in the Adirondack Mountains region of New York State, USA. A consistent pattern of slight discharge (never exceeding 105 mL m−2 h−1) was observed at three stations along a segment of the shoreline near the inlet stream. A distinct temporal pattern of seepage was observed at three stations along another portion of the shoreline. Seepage discharged (>400 mL m−2 h−1) for a portion of the summer in 1998 and then shifted to recharge (<−500 mL m−2 h−1) for the remainder of the summer. A similar temporal pattern was observed again in 1999 but the transition to recharge occurred earlier and higher rates of discharge (610 mL m−2 h−1) and recharge (−608 mL m−2 h−1) were recorded. Additionally, seepage at these three stations increased after large rainfall events and a pronounced episodic increase of seepage was measured during snowmelt. Distinct seepage patterns along portions of the shoreline show that seepage can vary considerably within seasons and suggests a need to consider changes of seepage over time periods of days to weeks as well as among seasons and years. This study demonstrates that the resolution of temporal seepage data can be important to the understanding of water fluxes to aquatic ecosystems.