Subsurface agricultural irrigation drainage: the need for regulation

Area of Science:

• Environmental Science
• Ecotoxicology
• Water Resource Management

Background:

• Subsurface agricultural drainage in the western U.S. poses a significant toxic threat to fish and wildlife.
• Contaminants in this drainage, including trace elements and salts, have poisoned migratory waterfowl in national wildlife refuges.
• This pollution violates the Migratory Bird Treaty Act and threatens critical wetlands and public health.

Purpose of the Study:

• To highlight the environmental and public health risks associated with subsurface irrigation drainage.
• To advocate for the regulation of agricultural subsurface drainage as a specific class of pollution.
• To propose a regulatory strategy for managing toxic irrigation wastewater.

Main Methods:

• Review of U.S. Department of the Interior studies on drainwater contaminants.
• Analysis of the composition of subsurface irrigation effluent, including trace elements, salts, and nitrogenous compounds.
• Examination of the National Pollutant Discharge Elimination System (NPDES) permit process for wastewater management.

Main Results:

• Drainwater contains toxic concentrations of pollutants, some classified as EPA priority pollutants exceeding toxic waste criteria.
• On-farm drainage systems offer point-source identification for wastewater.
• A four-step regulatory approach (site evaluation, contaminant reduction via NPDES, compliance monitoring) is presented.

Conclusions:

• Subsurface irrigation drainage requires specific regulation under the NPDES process.
• Active U.S. Environmental Protection Agency (EPA) involvement is crucial for implementing adequate wastewater controls.
• Environmental sound management of this effluent is necessary to protect wildlife and public health.