Bacterial Water Quality Sampling
Russian River | Santa Rosa Creek
Results of bacteriological sampling at selected locations in the Russian River are available through the Sonoma County Health Department web page.
What are you testing for?
The primary purpose of this monitoring program is to monitor these waters for bacteria content. Analysis for levels of total coliform, fecal coliform, Enterococcus, and Escherichia coli are of primary concern. Other measurements taken on the water may include dissolved oxygen content, pH (hydrogen ion activity), conductivity (ionized or dissolved minerals in the water), water temperature, and turbidity (clarity). These parameters are measured in the field and can provide an indication of whether conditions of concern exist at the time of sampling. For example, a lower than normal dissolved oxygen reading can indicate the presence of decaying matter; a higher than normal turbidity could indicate a recent discharge of sediment; or a higher than normal conductivity reading could indicate the presence of a nonpoint source runoff of animal wastes (which are high in ionized salts).
Where do these bacteria come from and what does it mean to me?
Sources of these bacteria include the natural environment (soils and decaying vegetation), stormwater, urban runoff, animal wastes (both wildlife and domestic animals), and human sewage. Analysis for coliform, Enteroccoccus, and E. coli bacteria is widely used as an indicator test. Coliform is a heading that describes a type of bacteria, which includes E. coli. It is found within the intestines of warm blooded animals, though most water contamination comes from cattle and people. Enterococcus is much like coliform bacteria, but is known to have a greater correlation with swimming-associated illnesses and is less likely to die-off in highly saline water. While these bacteria normally occur at low levels in the environment, high levels can indicate contamination (but do not cause illness) and the presence of other harmful pathogens. These pathogens, if contacted, could result in such symptoms as diarrhea, cramps, and nausea. These symptoms are not limited to the effects of contact with contaminated water, however, and may be caused by other factors.
What are the water quality standards for bacteria?
The California Department of Health Services (DHS) has the following draft
guidelines:
Total Coliform: 10,000
per 100 ml
Fecal Coliform: 400
per 100 ml
Enterococcus: 61
per 100 ml
E. coli: 235
per 100 ml
These guidelines have not been adopted as a standard at this time, which means
both that they may change and that they are not enforceable.
The Basin Plan objectives for fecal coliform state that median 30-day levels (based on a minimum of 5 samples/30 days) should not exceed 50/100 ml and that no more than 10% of those samples should exceed 400/100 ml. A 30-day median is determined by arranging the daily sampling values in ascending order (ex 20, 30, 50, 80, 120) and selecting either the middle number in that arrangement (50) or, if there is no one median number (20, 30, 50, 80) the mean of the two centermost (40). Levels that do not meet Basin Plan objectives do not necessarily pose a health threat, but instead indicate the need for further investigative sampling. For the data presented here, numbers in blue denote exceedance of Basin Plan objectives, and numbers in red denote exceedance of Department of Health Services guidelines.
Where do these standards come from?
The California Department of Health Services' "Draft Guidance for Fresh Water Beaches" describes bacteria levels that may require posted warning signs in order to protect public health. However, it must be emphasized that these are draft guidelines, not adopted standards, and are therefore both subject to change (if it is determined that the guidelines are not accurate indicators) and are not enforceable.
The Water Quality Control Plan for the North Coast Region (Basin Plan) prevents degradation of water quality by outlining the Region's water bodies, stating their beneficial uses, and setting objectives to protect those uses. Beneficial uses of the region's water bodies include municipal and domestic water supply, agricultural and industrial water supply, recreation, commercial and sport fishing, warm and cold freshwater habitat, wildlife habitat, and fish migration and spawning.
Revising Freshwater Bacteria Standards
The Water Quality Control Plan for the North Coast Region (Basin Plan) contains a fecal coliform bacteria freshwater water quality objective for the protection of waters designated with the contact recreation beneficial use (REC-1). Water quality objectives present in the Basin Plan were developed in the 1970’s and were based on the California Department of Health Services’ (DHS) recommendation at that time. However, since the 1970’s, the U.S. Environmental Protection Agency (USEPA) and the DHS have recommended standards that differ from the current Basin Plan freshwater bacteria objective.
The State Water Board, USEPA, and the Regional Water Boards rank the need for incorporating revised freshwater standards into basin plans as the highest statewide priority. A Statewide contract to develop revised statewide bacteria objectives for both fresh and estuarine waters is currently in progress. The revised statewide bacteria objectives were taken before the State Water Board in 2006, but have not been adopted to date.