EFFECTS OF WATERFOWL MIGRATION ON WATER QUALITY IN A GROUNDWATER-FED QUARRY LAKE

Krystal Lake in Chazy, NY occupies a former limestone quarry that was abandoned in the early 1960s. The roughly rectangular lake basin is approximately 500 meters long, 200 meters wide and has a maximum depth of 18 meters. The oligotrophic lake is predominantly groundwater fed with no permanent surface water inputs or outflows. The watershed is mostly undeveloped secondary woodland and apple orchard. The lake has relatively little shallow-water area but is a popular staging area for migrating geese in the fall; notably Canada Geese (Branta canadensis) and Snow Geese (Chen caerulescens). The objective of this study was to assess the impact of migrating waterfowl on the lake’s water quality.

Water quality indicators (nitrate-N, total phosphorus, soluble reactive phosphorus, sulfate-S and chloride) were measured at approximately weekly intervals in samples collected from depths of 3–5 m, 6–12 m and 9–16 m at three permanent stations through the late summer and fall 2012. Surface water temperatures reached a maximum (26–27 ^oC) in mid-August and epilimnion thickness reached nearly 8 meters. The surface water temperature maximum coincided with an observed late summer algal bloom that persisted until surface water temperature decreased below about 20 ^oC in mid-October. The algal die-off approximately coincided with the beginning of the fall waterfowl migration. Goose densities reached a maximum in early November but were highly variable through the end of the migration period in early December.

Preliminary results indicate small increases in nutrients during the waterfowl migration period but the relationship is not straightforward. The observed variations reflect complex abiotic and biotic interactions between groundwater base-flow inputs, internal lake processes, algal growth and decay, waterfowl migration inputs and agricultural runoff.