California | January 4, 2021

The EPA has released the second National Rivers and Streams Assessment report.

A product of the Clean Water Act, NRSA (National Rivers and Streams Assessment report) is a part of the 4 NARS (National Aquatic Resource Surveys) overlooked by the EPA and is completed in efforts by tribes, states, and other federal agencies in order to maintain and survey the quality of water across the country through a scientific approach to monitoring. 

1.2 million perennial river and stream miles were surveyed to produce the below outcome, with the exception of fillets, which were only assessed in large river systems.

Key Findings for Chemical indicators:

  • Total phosphorus, total nitrogen, salinity, and acidification are the chemical stressors surveyed in the waterways as a chemical indication of any stress to the waterways. 
  • Calculated by the phosphorus relative to the least-disturbed reference distribution, 58% of waters served were rated poor.
  • Calculated by the nitrogen relative to the least-disturbed reference distribution, 43% of waters served were rated poor.
  • These ratings conclude that when water ways are rated poor for nutrients then biological conditions based on the benthic macroinvertebrates were 2 times more likely to be poor as well.

Key Findings for Biological indicators:

  • Benthic Macroinvertebrates (dragonfly, stonefly larvae, snails, worms, and beetles) and fish are surveyed for a biological indication of any stress to the waterways. 
  • Calculated by the macroinvertebrate scores relative to the least-disturbed reference distribution, 30% of the biological indicators were rated good
  • Calculated by the fish scores relative to the least-disturbed reference distribution, 26% of the biological indicators were rated good.

Key Findings for Human Health indicator:

  • 69% enterococci (bacteria present with fecal) found below the criteria recommendation of the EPA in waterways. 
  • 0.1% of waterways had microcystins(toxins produced naturally from algae) concentrations that were higher than what the EPA recommends to be safe for swimming.
  • 24% of river miles contained methylmercury above the EPA criterion recommendation for fillet (fish).  
  • 40% of waterways surveyed found PCBS (man made chemicals that can be toxic) in fillets above the EPA human health fish tissue standard.
  • 3% of the surveyed rivers displayed PFOS (perfluorooctane sulfonate-an synthetic compound that can be dangerous to humans & the environment ) in fillets from fresh water. 

Key Findings for Physical habitat indicators:

  • 64% of river miles and streams are a good habitat for fish.
  • 58%  of the waterways are good for riparian vegetation (strips of vegetation surrounding the river).
  • 52% of the streambed sediment levels are good.
  • These ratings conclude that when sediment levels were rated poor benthic macroinvertebrate are two times more likely to be a poor rating than if the sediment levels were rated good or fair.

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