How does the construction of dams impact California's ecosystems?

The construction of dams significantly disrupts natural river flows and habitats, which is why this answer is correct. Dams alter the natural dynamics of rivers by changing the flow rate and sediment transport, leading to a cascade of ecological consequences. For instance, the alteration of water temperature and quality can affect the organisms that are adapted to specific conditions in free-flowing rivers. Many fish species rely on migration patterns that are disrupted by dam construction, leading to declines in native fish populations and weakening the overall aquatic ecosystem. Additionally, the alteration of sediment flow can inhibit the natural process of habitat renewal in riverbanks and deltas, further impacting the biodiversity that those environments sustain.

While constructing dams may create new recreational opportunities or promote certain activities, these benefits do not counterbalance the ecological disruptions caused. Similarly, the claims that dams enhance fish populations or promote greater biodiversity do not hold true when considering the broader environmental impacts, particularly on species that rely on natural river systems for their life cycles.