As we discussed several months ago in this column, one important water sample the stream monitors from Stillwaters Environmental Center take every month at our monitoring sites (see map) is to measure fecal coliform bacteria.

Fecal coliform bacteria are non-disease causing bacteria typically found in the gut of warm-blooded animals like dogs, cats, horses, cows, and people. They can also be found in bird droppings and in waste from wood processing plants.

They are measured from water samples by spreading some of the water sample on a growth medium and seeing how many colonies grow, and the measurement unit is CFU/100 ml which means “colony forming units per 100 milliliters of water. While it sounds pretty technical, it just means the amount of these bacteria can be estimated and that number tells us something about the health of our waters.

Bacteria enter out stream directly by wildlife, indirectly from runoff from cow or horse manure deposited close to a waterway or from human septic tank wastes flowing too quickly through groundwater. The amount of bacteria changes with the season and other factors because they are alive.They grow quickly when the water temperature is just right, but they can be killed more quickly by very low temperatures or by exposure to salt water.

These bacteria being measured are not harmful to humans or animals themselves but they are measured because they are indicators that other disease-causing organisms such as viruses or parasites are present. Fecal coliforms are much easier to measure than the pathogenic organisms for which you would have to filter many gallons of water to get enough viruses to make an accurate measurement.

Washington State set the bacteria standards for marine waters to match the standards set for shellfish harvest. So rather than setting standards like those for freshwater streams where swimming or wading exposures are calculated, these standards are set considering how much bacteria a clam or oyster could accumulate living in water contaminated by human, animal or other waste containing bacteria.

With Stillwaters six years of monthly fecal coliform data we can begin to see whether there are reasons for concern when using the Appletree Cove and Carpenter Creek estuaries and their shellfish resources.

We see a mixed review for these estuaries. While the fecal coliform numbers measured are typically low they also have periodically been very high value. Each sampling station exceeded one or both of the state water quality standards during the 2004-05, 2005-06 and 2006-07 water years (June through May of the next year). The 2007/08 water year Sites A, B, and C exceeded one or both standards. The 2008/9 Sites A and C exceeded standards.

So far in the 2009/10 water year only Site A has exceeded standards while all the rest of the sites have been in compliance. The salt marsh, site A, is the most variable.

The open water at the Kingston Marina is the most consistently low in bacteria. For site A and C most of the high values appear to occur in the warmer months however, Site B, where there are perhaps more influence by bird use, exhibits some high values in the winter months.

These values tell us that there is reason to continue to watch our estuary areas closely.

Betsy Cooper is a board member and stream monitor at Stillwaters Environmental Education Center. She also serves on the Kingston Citizens Advisory Council.