Observation network
The ECCC Algoma CAPMoN (Canadian Air and Precipitation Monitoring Network) site (47°02’01.2”N, 84°22’44.3”W), located about 600 m outside the watershed boundary (Figure 1), has measured atmospheric chemistry at the site since 1980. Constituents monitored include wet deposition (rain or snow) of major ions, (inferential) dry deposition and concentrations of acid-forming gases and particles. A meteorological station at the CAPMON site measures air temperature, wind speed and direction, relative humidity and vapour pressure, barometric pressure and solar radiation.
The TLW drainage system consists of first order streams and a cascading chain of 4 lakes. The Batchawana (separated into upper and lower basins), Wishart, Little Turkey and Big Turkey Lakes (surface areas of 6, 6, 19, 19 and 52 ha, respectively) are connected by Norberg Creek, which drains into Lake Superior via the Batchawana River (Figure 1). The lakes flush quite rapidly, with water renewal times ranging from 0.2 years at Wishart to 1.2 years at Upper Batchawana (Jeffries et al., 1988). Historically (1980 to 2019) lake temperature profile and chemistry, and lakeoutflow discharge and chemistry data were collected along the drainage network.
Stream flows and chemistry are monitored on an ongoing basis at v-notch weirs installed at 13 first order catchments within the watershed. These catchments vary in their topography from upland dominated with steep slopes to those having more moderate relief with swamps (Jeffries et al. 1988). Variation in stream hydrology and chemistry reflect these differences in basin topography and soils (Beall, Semkin & Jeffries, 2001; Creed, Sanford, Beall, Molot & Dillon, 2003; Leach, Buttle, Webster, Hazlett & Jeffries, 2020; Nicholson 1988). The catchments have a snowmelt-dominated hydrologic regime. The dominant anions in stream water are alkalinity (primarily HCO3-) and SO42-, with NO3- and Cl- as minor components. The dominant cation is Ca2+, with lesser amounts of Mg2+, Na+, and K+. Basins at lower elevation with presence of deep tills have higher average alkalinity and Ca2+concentrations than bedrock dominated higher elevation catchments.
Hydrometeorology and surface water chemistry measurements make up the core monitoring at TLW; however, other ecosystem components, such as physical and chemical properties of throughfall, soil, soil pore water, groundwater, structure and composition of overstory and understory vegetation and abundance and composition of stream and lake aquatic biodiversity have been monitored at locations within the watershed (Table 1). Several experimental manipulations have been conducted at TLW, such as enhanced acidification experiments (Hogan, 1992; Thirukkumaran & Morrison, 1996) a comprehensive forest harvesting experiment (Buttle, Webster, Hazlett & Jeffries, 2018; Leach, Buttle, Webster, Hazlett & Jeffries, 2020; Kreutzweiser, Capell & Good, 2005; Morrison, Cameron, Foster & Groot, 1999; and a nearshore aquatic habitat manipulation experiment (Smokorowski, Pratt, Cole, McEachern & Mallory, 2006).