Fig. 1, Emily measuring water height above weir board with Bob Livingstone.
Last October a seventh grader, Emily Tietje, from Falmouth Academy wrote a letter to then Board Chairman Jonathan Davis. She expressed an interest in doing a project at the weir and its effect on the salinity of the Pond. This was to be her science project for the year. She also wanted to contact several of the scientists sho had worked on the Pond and were familiar with the workings of the weir. Chairman Davis responding to Emily's letter had emailed Board members saying, "We obviously want to encourage this kind of participation," and further asked for help from a member to assist Emily with her project.
Since I had known the Tietje family for years, and since Emily's father Jim had worked with my late son Bruce summers at the Falmouth Yacht Club, I offered to help with Emily's Project. I had found out that Emily had already researched her project by going to OPET's website (www.opet.org) and had referred to K.O. Emery's A Coastal Pond Studied by Oceanographic Methods. She had also discussed her project with her science teacher Dr. Audrey Meyer.
My first meeting with Emily was last Fall [2000] the afternoon of November 9 at the Trunk River. She had brought her dad along. There the three of us, Emily, her father, and I walked to the point where the river stream flows into the wider opening Lagoon. This is the area known as the sill which over time had built up to the point of blocking all tidal flow into Oyster Pond except for the occasional wind-driven storm tides. Work had not yet begun to rebuild the Trunk River groins plus some dredging of the Trunk River channel.
The next location where we met was the weir. I talked to Emily and her father about several aspects of collecting water samples. I also had Emily measure the height of the water from the top of the weir board to the water surface (see figure 1). I suggested that she record for each sample the direction of water flow (in or out), and perhaps she should consider samples from several other locations. These might inlcude the Lagoon, the South shore, and Spohr Garden Dock, which represents the halfway point North in the Pond.
Fig. 1, Emily measuring water height above weir board with Bob Livingstone.
Following my instructions I had Emily collect a water sample. (see Fig. 2)
Fig. 2, Emily collecting a water sample on the upstream side of the weir.
After the sample was collected, Emily was prepared to measure the temperature in Centigrade and to determine the salinity for this location. (See Fig. 3)
Fig. 3, Emily determining salinity by a specific gravity method: filling a container with the sample and taking a surface reading from a floating hydrometer. The value read was then referred to a table corrected for temperature (Centigrade). The salinity (ppt) was read off from the table. Father Jim assisting.
Emily's project at the weir went from November 2000 to January 2001. Weir samples up to last week in December gave salinity readings of 0.0 ppt including the one (Fig. 3) taken on November 9, 2000. Oyster Pond was still a nearly fresh water environment.
In her report Changing salinity at Oyster Pond Weir (Science Period 2 for Dr. Meyer) Emily notes that the highest salinities measured were storm related: January 1, 2001 (12 ppt) and again January 21, 2001 (14 ppt). I also had a salinity of 15.6 ppt on January 21, 2001 - storm related.
Many of the samples collected for Emily's project were driven during the winter cold period. Water temperatures at the weir were between 2 and 3 degrees Centrigrade - cold. I remember Jim with his sledge hammer trying to open up a space in the ice under Spohr's Dock. Oyster Pond froze rather solid. Because of the ice, Emily and her father gave yeoman's service to OPET. The Board should be deeply greatful.
Peter Cook and his wife Dale with their company SEA STONE did the work on rebuilding the Trunk River groins along with some dredging of the river including the sill. I have a photograph December 21 when dredging the sill area began. Soon after this the level in Oyster Pond as measured at the weir dropped 23 cm (about 9 inches). At this date July 2, 2001 the tidal flow into the Pond is still a bit of a mystery. But even with the sill reforming, some salt water has entered the Pond. Recent readings of salinity have shown the Pond to be approximately 2.0 ppt.
Photo of jetty construction by Robert Livingstone.
This page updated July 1, 2004.