Kidd, Jessica2025-08-182025-08-182025-08-182025-08-13https://hdl.handle.net/10012/22192This thesis investigated ways to gather, archive, share and use the knowledge needed to inform effective Cumulative Effects Assessment (CEA) for freshwater ecosystem protection and restoration. Specifically, this thesis focuses on methods for collecting, managing, and applying long-term regional data needed to characterize baseline conditions and monitor cumulative effects by addressing the following four questions: 1) Can community-based monitoring (CBM) collect long-term regional biophysical data needed for effective CEA; 2) How can long-term regional freshwater data be managed and shared so that it is reusable for CEAs; 3) How can long-term regional surface water data be analyzed to estimate baseline conditions and identify areas impacted by cumulative effects; and 4) Can the restoration of water bodies impacted by cumulative effects be improved with knowledge that is foundational for effective CEAs? Results of a pan-Canadian analysis of CBM projects confirmed that CBMs can contribute robust, valuable long-term regional biophysical data to CEA. As part of this analysis, project characteristics that should be considered when designing CBM projects for integration/use in CEA were identified. Insights gained from interviews with technology sector experts guided the development of recommendations that will make freshwater data open and reusable within the freshwater science sector. Natural Range of Variation (NRV) calculations (Tukey Inner Fence or median ±2 median absolute deviation methods) were used to estimate surface water quality baselines which, when paired with Mann-Kendall trend analysis and spatial assessment of regional concentrations, provided a robust approach for assessing cumulative effects in freshwater ecosystems. Finally, known deficiencies in conventional approaches to urban water body restoration were addressed through application of the foundational elements of effective CEA to a case study of a degraded lake (Frame Lake) located in Yellowknife, Northwest Territories. This thesis defines the types of information that should inform freshwater ecosystem decision-making and articulates how that information can be obtained, managed and used.encumulative effects assessmentwatershed monitoringwatershed planningenvironmental impact assessmentcommunity-based monitoringfreshwater datanatural range of variationurban water body restorationfreshwater ecosystem protectionNATURAL SCIENCES::Biology::Terrestrial, freshwater and marine ecology::Freshwater ecologyDoctoral Thesis