Source: Assadian, N.W., L. Esparaza, L. Fenn, A. Ali, S. Miyamoto, U. Figueroa, and A. Warrick. 1998. Spatial variability of heavy metals in irrigated alfalfa fields in the upper Rio Grande River Basin. Agric. Water Manag. 36:141-156.

Because of the decrease in quality of wastewater discharge in the Rio Grande River, crop contamination and heavy metal deposition onto fertile soils has become a growing concern. The Rio Grande River serves as the international boundary between Texas and Mexico, and farmers on both sides contend that the decline of water quality from the river has contaminated fertile soils and reduced crop yields. There are many factors, both past and present, that contribute to the instability of water quality in the Rio Grande. In recent years, this region's economy has dramatically shifted from agriculture production to manufacturing. This has caused a boom in population and brought many industrial plants to the upper basin of the Rio Grande River. On the Texas side, wastewater is treated and then discharged into the Rio Grande. On the Mexican side, raw sewage is directly discharged into open irrigation canals and finds its way to the river. Atmospheric fallout from factory fumes are an additional source of heavy metals that can be easily transported into agriculture fields by river water. With limited water supplies and growth of population along the border, farmers will be forced to depend more on urban effluents for irrigation. To achieve sustainability of water quality in the future, an international commitment is needed. Future water management practices should include deviation of degraded waters directly away from farmland rather than mixing these waters within the Rio Grande River. Better use of sanitation practices and stronger control of raw sewage and industrial waste discharge would improve the sustainability of water quality in the Rio Grande. The authors conclude that an increase in metal loading is already taking place, particularly for Cr and Cd in Mexico, and additional loads from degraded waters are possible without regulation of water and soil management.

Abstract author: Matthew David VerMilyea, 5 November 1999.

SUSAG Abstracts: Go back to the SUSAG Abstracts search page.