Letter: Evidence is clear — Hix Bridge debris hurts oysters

To the editor:

The Westport River Watershed Alliance must politely disagree with the gentleman regarding the Hix Bridge granite block removal project.  Most of what we know about this situation and the oysters has come from Dr. Ken Perez, a former EPA scientist, who is volunteering his time to improve our river by working on this project.  Other scientific articles have confirmed Dr. Perez’s expertise.

WRWA believes the gentleman’s observations refer to flow on the surface and in that regard, he is right – the flow restriction is not significant on the surface.  It is the flow at the bottom of the river that is severely restricted by the granite blocks that were pushed over into the channels when the bridge was rebuilt after the 1938 storm.

A bathymetric study of the Hix Bridge channel, commissioned by the Army Corps of Engineers, confirms this fact.  For further evidence, we have devised a study with oysters at different levels and in a high and low flow areas to demonstrate a well known scientific fact — oysters are healthier in high flow areas.

Right now wild oysters are having a tough time repopulating north of the bridge because of the sediment that has built up in the deeper water. The sediment eventually buries them alive. Opening up the channels will increase the tidal flow and allow the sediment to move downstream where it will decompose or move out with the tide.

I don’t disagree with his “Additional Facts” except to repeat that it is the granite blocks that have choked off the tidal flow in the deeper water above the bridge.  The blocks retain the sediment above the bridge.  It is not the surface water, where he is correct – the flow is unchanged – that is a concern.  It is the deeper water.

Our own survey of oysters above and below the bridge confirms our theory.  The oysters that are below the sediment line above the bridge are dead.  The new spat that are above the sediment are still alive.  The few oysters that are big enough to take hold above the bridge, but partially immersed in the sediment, are sickly with paper thin shells that break when you try to open them.

To address the poor health of the oysters at his dock .6 miles below the bridge, they may be in a low flow area with a lot of sediment.  In addition, without the abundant supply of spat from the historically large oyster beds north of the bridge, the rest of the river downstream will logically have fewer oysters.

Dr. Perez and I will make ourselves available to meet with anyone who has questions about the project.

Matt Patrick

Executive director, Westport River Watershed Alliance

 

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