How Drought Affects River Flow Across the US

2026-04-25

Drought has profound effects on river systems that extend far below the surface. During drought, baseflow from groundwater decreases as water tables drop. Snowpack-dependent rivers in the West face earlier and lower spring peaks. The Colorado River has seen its flows drop 20% since 2000 compared to the 20th century average, driven by aridification and reduced snowpack

. Agricultural diversions during drought further reduce instream flows, creating feedback loops that stress ecosystems. Low flows concentrate pollutants, raise water temperatures, and block fish passage. Tributaries dry completely, disconnecting habitats. The economic impact runs into billions: hydroelectric generation drops, barging becomes impossible on rivers like the Mississippi, and irrigation restrictions hit farmers hard..