A Study of Salinity in Effluent Lakes, Puerto Penasco, Sonora, Mexico

Abstract

An investigation of salt build -up in two saline discharge lakes was conducted during 1979 in Puerto Peñasco, Mexico. Salt water was discharged to the smaller, deeper Lake I from a shrimp aquaculture prototype at an average rate of 70 liters per second. Water flowed to Lake II through a short channel, and exited the system through either evaporation or infiltration into the underlying sandy soil. In an attempt to differentiate between the evaporation and infiltration terms in the water budget, salt-budget equations have been derived for the two-lake system. These equations have been approximated in a series of monthly time steps, using averages of weekly salinity and water level measurements. Due to imprecision in the data, meaningful results have been obtained only for Lake II. The average calculated infiltration rate is 0.015 meters per day, and calculated evaporation rates show good correspondence with pan evaporation records for a station 2 kilometers away from the lakes. Examination of the salt budget equations shows that, under steady-state conditions, the ultimate salinity is finite. Thus, the maximum expected salinity of a lake may be calculated from worst-case (summertime) values of lake volume, inflow, evaporation, and salinity of incoming water.