Part of the Stillwaters’ monthly monitoring program focuses specifically on the marine nearshore and salt marsh areas that are fed by Carpenter Creek. One of the unique qualities of these aquatic ecosystems is the presence of dissolved compounds in the water, particularly salts. The total gram weight of dissolved salts in one kg of seawater is referred to as salinity.

According to “Oceans” by Karl Turekian, there are 12 chemicals that make up “salt” in salinity, but 85 percent of the salt is good old table salt, sodium and chlorine. These dissolved compounds affect what species can live in these waters, and they prevent oceans and our estuary from freezing during the winter.

Daily changes in weather and currents will cause salinity to vary. In our estuary – where the salty water from the Puget Sound and the freshwater from Carpenter Creek and other direct freshwater drainages meet – salinity can very several parts per thousand (ppt).

At our monitoring sites we measure conditions in several very distinct environments. First, the salt marsh is a special place where the freshwater draining from the whole of the Carpenter Creek watershed begins to be diluted with periodic incursions from the saltwater pushing its way into and over the salt marsh area. The salinities measured in the salt marsh site (site A on monitoring map) tend to have salinity readings of from 0-4 ppt, a very dilute influence of salts. However the presence even that amount of saltwater has an effect on the plants that can live there, and make it a place where tiny salmon, which start their life in freshwater, can begin their transition to a saltwater life.

The next place we monitor, just south of West Kingston Road (Site B), the water is constricted from mixing fully with the fresher salt marsh, so it is more significantly influenced by the Appletree Cove estuary water. The salinity measured in this area has a range of 22-29 ppt. Here you see totally different plant species, those that live in salty conditions happily. For example, pickleweed can be totally submerged or be fully exposed at low tide. It is used as food plants by the larval aquatic organisms, and can be very tasty for humans in salads (tastes a bit salty though).

We also measure salinity at Arness Park, where we stand on the rocks and dangle our monitoring probe from a pole out into the water. At this point, we are outside of the estuary and in Appletree Cove, but we are still near the culvert where freshwater sources are contributing water and surface runoff affects salinity. The range of salinity here is 18-30 ppt, which is not a big difference from the estuary.

Finally, at the marina (Site D) we have observed a slightly higher salinity on average: 28.11 ppt. However, like the estuary sites, we have seen a wide range of salinities even at this site (19 – 30.77). These measurements give us an appreciation for the special adaptability our marine organisms must have to live day to day in our waters.