The Management of Lake Chapala (México): Considerations After Significant Changes in the Water Regime

Abstract

ABSTRACT Forty-five percent of the water from the river supplying Lake Chapala has been diverted in the past 10 years. The water quality consequences of this change in water quantity are numerous. In this period, the lake volume has declined by 50 percent. Because of the reduced flushing and the corresponding relative increase in outputs via evaporation more than twofold, the lake's total dissolved solids content has increased. A second consequence, and one of great importance to the ecology of the lake, is the increase in water turbidity. With a reduction in lake mean depth from 7.2 m to 4.5 m, wind-driven resuspension of the inorganic sediments has increased. This has caused light limitation of phytoplankton production to the extent that nutrient loading models to predict production of biomass fail when applied to this lake. Reduction in turbidity by increased flocculation could significantly speed up the eutrophication process, because high concentrations of nutrients are present in the system (total i...