Model describes sustainable long-term recycling of saline agricultural drainage water

Due to high water tables, the western San Joaquin Valley is prone to high salinity in drainage water, which requires appropriate management and disposal in order to sustain agricultural productivity. We developed a model that describes a farming system for irrigating a salt-tolerant crop with high-salinity drainage water from a salt-sensitive crop. The farming system would include the collection of subsurface drainage water from the salt-sensitive crop, which would then be combined with good, low-salinity water for an average electrical conductivity (EC) of 5 deciSiemens/meter (dS/m); irrigation of the salt-tolerant crop(s) (cotton, in this case) for several cycles; and final disposal of the drainage water in an evapor-ation pond. The main benefits of this system are that the proportion of the farm required for evaporation ponds decreases and fresh water is saved. According to our calculations, this farming system could be physically sustainable for centuries. However, the costs related to mitigating wildlife impacts caused by ecotoxic salts such as selenium in the evaporation ponds must be fully evaluated to determine the system's economic viability.