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The article discusses the ecological aspects of the restoration of the Colorado River through the managed flood from the Glen Canyon Dam. It states that the Colorado river ecosystem was significantly altered after the closure of the closure Glen Canyon Dam in 1963, and mentions identification of strategy for protecting the downstream ecosystem which was described in the Glen Canyon Dam Environmental Impact Statement. It notes analysis of the flood on canyon resources.

Mediterranean forests are highly susceptible to wildfires, which can cause several impacts not only within burnt areas but also on downstream aquatic ecosystems. The ashes' washout from burnt areas by surface runoff can be a diffuse source of toxic substances, such as metals, when reaching the nearby aquatic systems, and can be noxious to aquatic organisms. The present work aimed at assessing the ecotoxicological effects of post-fire contamination on two aquatic producers (the microalgae Raphidocelis subcapitata and the macrophyte Lemna minor) through in-situ bioassays, validating the obtained results with the outcomes of laboratory bioassays with surface water collected simultaneously. Four distinct sites were selected in a basin partially burnt (Ceira river basin; Coimbra district, Portugal) for bioassay deployment: one site upstream the burnt area in the Ceira river (RUS); three sites located under the influence of the burnt area, one immediately downstream of the burnt area in the Ceira river (RDS) and the other two in tributary streams within the burnt area (BS 1 and BS 2). The in-situ bioassays lasted for 13 days and began following the first post-fire major rain events. Results showed that the microalgae growth rate was able to distinguish the three sites within and downstream of the burnt area (BS 1 , BS 2 , RDS) from the site upstream (RUS). By contrast, the macrophytes growth rate only allowed to differentiate between the sites within the burnt area (BS 1 and BS 2) and those up- and downstream of the burnt area (RUS and RDS). The in-situ results for both species were corroborated with the results of the laboratory experiments, supporting the use of laboratory surrogates for a screening assessment of wildfire impacts in aquatic ecosystems. Direct causal relationships between the observed ecotoxicological effects on R. subcapitata and L. minor and the physical-chemical parameters of the water samples were difficult to establish, although the results suggest (i) a role of differential major and trace metal load in explaining species growth variation; (ii) interaction between metals and/or between metals and other field parameters are likely to modulate the biological responses to the challenges deriving from wildfire runoff. • The input of toxic compounds, as metals, in post-fire scenarios, can be harmful for freshwater primary producers. • The use of in-situ assays with freshwater producers allowed establishing broad causal relationships. • More research is needed to better understand the impacts of post-fire contamination in the freshwater ecosystem functioning. [ABSTRACT FROM AUTHOR]