part, and it is at best not a common usage. Causes Freshets are the result of the mass delivery of water to the landscape, either by snowmelt, heavy rains, or a combination of the two. Specifically, freshets occur when this water enters streams and results in flooding and high flow conditions. When freshets occur in the winter or early spring, the frozen ground can contribute to rapid flooding. This is because the meltwaters cannot easily infiltrate the frozen surface and instead run overland into rivers and streams, leading to a rapid flooding response. Deeper snow packs with large snow water equivalents (SWE) are capable of delivering larger quantities of water to rivers and streams, compared to smaller snowpacks, given that they reach adequate melting temperatures. When melting temperatures are reached quickly and snowmelt is rapid, flooding can be more intense. In areas where freshets dominate the hydrological regime, such as the Fraser River Basin in British Columbia, the timing of freshets is critical. In the Fraser River Basin, the annual freshet was observed 10 days earlier in 2006 compared to 1949. In these areas, earlier freshets can result in low flow conditions later in the summer or fall. Freshets may also occur due to rainfall events. Significant rainfall events can saturate the ground and lead to rapid inundation of streams, as well as contributing to snowmelt by delivering energy to snowpacks through advection. In the tropics, tropical storms and cyclones can lead to freshet events. Ecology The magnitude of freshets depends on snow accumulation and temperature. Smaller freshets have been associated with El Niño conditions, where the milder conditions lead to lower snow accumulations. The opposite is true under La Niña conditions. Runoff from freshets is a major contributor of nutrients to lakes. In La Niña conditions with stronger freshets, higher runoff, and high nutrient inputs, more positive ecological indicator species (Arcellacea) are present in lakes, indicating lower levels of ecological stress. In El Niño conditions, smaller freshets contribute less runoff and result in lower nutrient inputs to lakes and rivers. In these conditions, fewer positive ecological indicator species are present. Migratory fish, such as salmon and trout, are highly responsive to freshets. In low flows present at the end of freshets, fish are more likely to ascend streams (move upstream). During high flows at the peak of a freshet, fish are more likely to descend streams. Biogeochemical Impacts Freshets