The US Environmental Protection Agency has recently released a final regulation for Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater. This involves the approval of several test procedures for measuring the toxicity of effluents and receiving waters, which are referred to as whole effluent toxicity or WET test methods. Visitors can download the entire 275 page document, its table of contents, individual sections, or the appendices. Anyone working in biomonitoring or other similar fields will appreciate the timely and important information provided.