Is it safe to swim in the Yuba River?

Whether it be due to strong currents and seasonally cold water or water quality impairments, there are a multitude of reasons why people may consider the Yuba River unsafe to swim.  Like any river people should always consider the risk of drowning when swimming in the Yuba, but what water quality impairments are important when deciding whether or not it is safe to swim?  

Many sections of the Yuba River are polluted with heavy metals such as mercury, arsenic, copper, and iron, but are levels high enough to cause health problems? No, levels are not high enough to pose health risks through contact recreation and therefore are not applicable when determining whether or not it is safe to swim. Although, people should still heed warning when deciding how much fish to consume from the Yuba due to fish mercury contamination.  To find out more about safe eating guidelines for fish,  visit the California Office of Environmental Health Hazard Assessment or click on the fish advisory map below. 

 OEHHA Fish Advisories Map 

From a water quality impairment standpoint, bacteria levels are what are important to monitor in order to determine if a water body is safe to swim.  Naturally there is bacteria in the environment, but fecal coliform bacteria (found in human and animal feces) can be used as indicators of possible sewage contamination.  In the past SYRCL has primarily tested for Escherichia coli (E. coli) contamination as well as Enterococcus, another type of fecal bacteria though not a coliform.    E.coli and Enterococcus by themselves are generally not harmful, but do indicate the possible presence of pathogenic bacteria, viruses, and protozoans that live in human and animal digestive systems.  Elevated levels of these bacteria can cause health problems and therefore pose risks to people coming into contact with the water.  Thus monitoring bacteria is important in order to determine if it is safe to recreate in the water.  The table below lists the water quality guidelines for bacteria monitoring.  


Water Quality Guideline

E. coli (MPN/100mL)

<235 MPN/100 mL (EPA Contact Recreation Guideline)

Total Coliform (MPN/100mL)

Presence a concern

E. coli O157:H7 (positive/negative)

Presence a concern

Crypotosporidium (oocyst/L)

Presence a concern

Giardia (cyst/L)

Presence a concern

Salmonella (MPN/100 mL) or (positive/negative)

Presence a concern

Enterococcus- Enterolert (MPN/100 mL)

61 MPN/100 mL (EPA Contact Recreation Guideline)

Enterococcus- MF (CFU/100 mL)

61 MPN/100 mL (EPA Contact Recreation Guideline)

Enterococcus-MTP (MPN/100 mL)

61 MPN/100 mL (EPA Contact Recreation Guideline)

SYRCL's bacteria data is separated by region and region tributaries, so to view the data click on one of the following: North Yuba, Middle Yuba, South Yuba, South Yuba Tributaries and Lower Yuba.  The picture below depicts monitoring sites where E. coli levels have been found to be unsuitable, suboptimal, or suitable, unless insufficient data exists.  

Due to budget constraints SYRCL has had to largely cut all bacteria sampling, but will be participating in the SWRCB Central Valley Safe to Swim Study for the fourth time this year at a select number of sites.  The purpose of the Safe-to-Swim Study is to determine if high use swimming areas have safe levels of bacteria. Click below to view reports and data from 2008 and 2009. 

SWAMP Safe-to-Swim Study, Labor Day 2008 Final Report 

SWAMP Safe-to-Swim Study, Labor Day 2008 Results 

SWAMP Safe-to-Swim Study, June 2009 Final Report

SWAMP Safe-to-Swim Study, June 2009 Results