The San Carlos Lake fish kill is a stark reminder of the ecological and economic risks posed by deteriorating water systems. The event has disrupted local ecosystems and raised alarms about the sustainability of water supplies for millions of Americans. Similar conditions threaten major reservoirs like Lake Mead and Lake Powell, which are critical for water delivery across the Western U.S. The Great Salt Lake and Lake Erie face different but equally severe challenges, including toxic algal blooms and rising salinity, which endanger aquatic life and public health.