Recent investigations reveal substantial shortcomings in chemical monitoring programs, with under 1% of the estimated 300,000 chemicals of environmental concern regularly assessed in U.S. surface waters. Comprehensive analyses linking millions of monitoring records to toxicity thresholds uncovered that many highly toxic substances remain undetected, undermining ecological risk assessments. Despite some progress in reducing heavy metal contamination through regulation, the vast chemical diversity and insufficient sensitivity of current monitoring hinder accurate evaluations of aquatic health risks worldwide, emphasizing the need for expanded and more sensitive surveillance systems.