The cui-ui is a large sucker fish endemic to Pyramid Lake and, prior to its desiccation in the 20th century, Winnemucca Lake in northwestern Nevada. It feeds primarily on zooplankton and possibly on nanoplankton. The maximum size of male cui-ui is approximately 53 cm (21 in) and 1.6 kg (3.5 lb), while females reach approximately 64 cm (25 in) and 2.7 kg (6.0 lb). A cui-ui typically lives for 40 years but does not reach sexual maturity until at least age eight. The cui-ui is an endangered species, and one of the few surviving members of its genus.

An hydrological transport model is a mathematical model used to simulate the flow of rivers, streams, groundwater movement or drainage front displacement, and calculate water quality parameters. These models generally came into use in the 1960s and 1970s when demand for numerical forecasting of water quality and drainage was driven by environmental legislation, and at a similar time widespread access to significant computer power became available. Much of the original model development took place in the United States and United Kingdom, but today these models are refined and used worldwide.