May 2017

The soup du jour being served in the Delta doesn’t sound very appetizing. And it appears to be having a significant effect on endangered fish. Estuary News recently reported on a new study underway at the U.S. Geological Survey which shows salmon, smelt and other at-risk fish are increasingly exposed to urban and agricultural pesticides that can have deadly effects on fish. The report sheds light on some important facts:Delta toxic soup can

  • A wide variety of insecticides, herbicides and fungicides are being detected in the Delta
  • More than half the pesticides applied in the Delta are not routinely trackedfish bowl w salmon & smelt
  • Pyrethroid use has greater correlation to fish abundance variability than water flows
  • Climate change likely increases the toxicity of pesticides in the Delta

The new research confirms a number of previously held views for continuing declines in native endangered salmon and other critical species. First, the research confirms multiple stressors, and not simply water flows alone, are the likely cause of the steep decline in native endangered species. Second, the combination of some pesticides, even below toxic levels, can have deadly synergistic effects for fish. Third, a wide variety of insecticides, herbicides and fungicides are creating a lethal brew in the Delta. Finally, the toxic soup results from both urban and agricultural sources in the Delta.

When combined, pesticides at sub lethal levels can have deadly synergistic effects on fish – and new monitoring in the Bay Delta shows that the water is a soup of urban and agricultural insecticides, herbicides and fungicides.

– Estuary News

Regulators and policymakers should take note. More rigorous monitoring, testing and regulation is clearly required of both urban and agricultural discharges in the Delta. Delta residents must be held accountable for polluting their own environment.