Lake water has been impaired with nutrients due to the synergic action of human-made activities and climate change. This situation is increasing eutrophication around the globe faster than before, causing water degradation, loss of its uses, and water-associated economic and health effects. Following the Sustainable Development Goal 6, more precisely its target 6.6, nations are already behind schedule in protecting and restoring water-related ecosystems (i.e., rivers and lakes). As concerns with eutrophication are escalating, eutrophic water remediation practices are the keys for restoring those lake waters. Diverse methodologies have been investigated focusing on the nutrient that limit primary productivity (i.e., phosphorus), but few have been applied to in-lake eutrophic water remediation. Thus, the objective of this paper is to provide an overview and critical comments on approaches and practices for facing eutrophic lake water remediation. Information on the successful cases and possible challenges/difficulties in the peer-reviewed literature are presented. This should be useful for supporting further remediation project selection by the stakeholders involved. In summary, for a successful and durable restoration project, external nutrient inputs need to be managed, followed by holistic and region-specific methods to attenuate internal legacy nutrients that are continually released into the water column from the sediment. When aligned well with stakeholder participation and continuous monitoring, these tools are the keys to long-lasting water restoration.

Climate change and human actions will exacerbate eutrophication cases in inland waters. By external or internal inputs, there will be an increase in nutrient concentrations in those systems worldwide. Those nutrients will bring faster trophic changes to inland waters and possible health and recreational advisories. A novel approach using a floating filtration system, a silt curtain, and geotextiles (woven and non-woven) is under investigation. This method has been applied as an in-situ pilot experiment deployed at Lake Caron, a shallow eutrophic lake in Quebec, for two summers. Turbidity, total suspended solids (TSS), total phosphorus (TP), blue-green-algae-phycocyanin (BGA-PC) and chlorophyll-a showed statistically significant average removal efficiencies of 53%, 22%, 49%, 57% and 56%, respectively, in the first year and 17%, 36%, 18%, 34% and 32% in the second. Statistical correlations were found with TSS, turbidity and variables that could represent particles (TP, turbidity, chlorophyll-a). Employing this in situ management method could be a promising remediation for not only shallow lakes (average depth <2 m) but also for ponds, rivers, coastal regions, bays and other water types, to enable cleaner water for future generations.

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