Restoring Herring River Starts with Removing a Nearly 100-year-old Dike
Recently I received in the mail a brochure from the Friends of Herring River, a non-profit group that is supporting the Herring River Restoration Project. For those of you who may not be aware of this project, which has been in the planning stages for several years now, a little background might be helpful.
The Herring River Valley in Wellfleet and Truro was one of the largest tidal estuarine systems on Cape Cod. It originally encompassed eleven hundred acres of salt marsh, intertidal flats and miles of tidal creeks. Then, in 1909, a dike was built across the mouth of Herring River, largely at the behest of local banana magnate Lorenzo Dow Baker. The purported purpose of the dike was to reduce mosquitos, though Baker also owned land along the river basin which might be developed if the wetlands were drained. The dike, unfortunately, didn’t reduce the mosquitos, but simply traded the native salt-water species for an equally voracious brackish variety.
What the dike did do was drastically reduce the tidal flow into the Herring River Valley, which in turn completely changed the character of the estuary. Over the past century the salt marsh has been reduced to a small fraction of its original extent. Non-native “invasive” species such as Phragmites grass took over a formerly productive salt marsh. Navigable tributaries became clogged and impassable, greatly reducing the number of alewives or migratory herring in the spring. Acidity in the system increased and oxygen levels dropped, resulting in fish and eel kills. And even the rich oyster beds outside the dike were closed in the 1980s due to fecal coliform contamination that was attributed to the poorly-flushed waters of the dammed up river valley.
Despite these consequences, the Town of Wellfleet continued to maintain and rebuild the dike for nearly 100 years. In 2003, the Herring River Valley was classified as “impaired” under the federal Clean Water Act, and the Town finally agreed that something needed to be done. After much discussion, an agreement was reached between local, state and federal officials that a new dike would be built with adjustable tide gates that would gradually be opened with the goal of eventually restoring full tidal flushing to the valley – a process that is projected to take decades to complete. Currently, construction of the new dike is scheduled to begin in 2017.
The brochure from the Friends of the Herring River paints a very rosy picture of what the gradual restoration of the river valley will look like. The expansion of salt marshes to their original extent will create valuable nurseries for commercial fish and shellfish. The annual herring and eel migration will greatly increase. The closed oyster beds, cleansed of contamination, will likely reopen. Invasive species will be replaced by native marsh plants. River tributaries will be restored, providing greater access for canoeing and kayaking. And that’s only some of the predicted benefits. Underlying all of these, however, is the basic assumption that increasing or restoring salt marsh habitat is always a worthwhile and desirable thing.
It’s a hard proposition to argue with. The many environmental virtues of salt marshes have been extensively documented. And I’m not arguing against it. I agree that the restoration of the Herring River Valley is a worthwhile project, and should be done. I do support it – just not without reservations, and next week I’ll tell you what some of those reservations are.