Freshwater quality in Skeleton Lake will be analyzed by conducting water column profiles in May to early June 2017 prior to snow melt and ice decay; and, in July 2016 following complete ice thaw. A multi-parameter water chemistry sonde will be deployed with dissolved oxygen (O2), pH, conductivity, temperature, and total algae sensors to determine transitional zones in the water column. Water from the upper, mid, and lower depths of the lake will be sampled and analyzed for a complete set of water chemistry parameters, including dissolved greenhouse gases and contaminants. To quantify Net Primary Production (NPP) in surface waters, I will deploy a raft equipped with continuously measuring sensors, including CO2, O2, and photosynthetically active radiation (PAR); along with an anemometer, barometric pressure and air temperature data loggers. A thermistor chain deployed from the raft will determine summer thermal mixing depths in surface waters. Dissolved O2 stable isotopes (d18O-O2) will be used to assess whole-lake metabolism by separating changes in O2 saturation due to temperature, and mixing, from changes due to metabolic activity. These will be coupled with measurements of stable carbon (C) isotopes for dissolved inorganic carbon (DIC) (d13C-DIC) and particulate organic matter (POM) (d13C-POM) to assess rates of net carbon metabolism. Water column respiration rates will be measured by incubating surface, mid, and bottom depth waters in dark glass containers equipped with O2 and CO2 sensors.