Shallow lakes are highly abundant in the Canadian Western Boreal Forest (WBF) and provide essential ecosystem functions, water resources, sources of biodiversity and anthropogenic values. Increasing exposure to resource development and climate change are putting these lakes at risk, raising the need for baseline data and an understanding of the controls on lake hydrochemistry to facilitate adaptive management. Understanding the natural variability of, and controls on lake connectivity and water quality is essential to help guide future land use decisions and management strategies intended to mitigate these complex environmental problems. Very few monitoring programs have been performed in the WBF region. This thesis therefore aims to provide insight in the natural variability of lake chemistry and provide reference material for managers to assess potential lake disturbances. This thesis studies the relationship of lake ion and nutrient chemistry with landscape characteristics to infer the processes driving the variability in lake hydrology. A first study investigates the influence of regional-scale landscape characteristics across four Canadian ecozones of the WBF, while a second study focuses on the influence of local-scale landscape characteristics within the Boreal Plains (BP). This first study illustrates that the WBF is more spatially variable in lake ion and nutrient chemistry than previously assumed. Water types delineated by multivariate regression trees (MRTs) were capable of addressing 38% of the variability in lake ion chemistry across the WBF, using the regional characteristics of depth of glacial overburden, bedrock geology types and permafrost. Graphical plots of end-members indicated that the processes of groundwater dissolution, hydrologic isolation and difference in continental-scale precipitation interact to produce distinct lake ion chemistries. Permafrost, peatland abundance, depth of glacial overburden and topographic position delineated water types explaining 31% of the variability in lake nutrient chemistry across the WBF. These identified water types did not adhere to individual Canadian ecozones or sampling areas, and policy makers must therefore consider the complex interactions occurring across the WBF nor assume that hydrologic processes acted uniformly across each of the ecozones. Using MRT analyses, the second study showed that different lake and catchment characteristics give rise to distinct shallow lake hydrochemistry signatures (both ion and nutrient) across the BP. Water types delineated by MRT analysis showed relative wetland connectivity and relative topographic position addressing 45% of the variability in shallow lake ion concentrations. 48% of the variability in lake water quality was explained using water types delineated by the regional hydrologic regime (i.e. recharge vs discharge) and the geologic setting the shallow lakes were situated in. Results of this study showed that comparing natural variability in BP shallow lake hydrochemistry requires a careful consideration of the hydrological landscape shallow lakes are located in. Both studies also assessed the correlations between variability in ion and nutrient chemistry, and found the two chemistry sets to be influenced by distinct processes. Research and surveys assessing lake ion chemistry therefore provide little insight in lake nutrient loadings, and vice versa. This thesis provides the natural range in lake chemistry variability for well-defined hydrologic landforms across the WBF as reference for managers to determine whether lakes have experienced disturbance or not. Additionally, this thesis shows managers and stakeholders that determining future land use practices in the WBF and its individual ecozones requires specific consideration of landforms in policy, regulation and/or adaptive practices to ensure pre-disturbance lake water quality and connectivity and to sustain the lakes’ ecosystem functions in the region.