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Ditch Remediation:
Questions & Answers
Why were ditches put into marshes?
Salt marshes have been ditched to remove surface water from the salt marsh and help dry out any area of standing water. Most commonly ditches were associated with mosquito control and salt haying. Salt hay ditches are generally narrower, shallower, and shorter than mosquito control ditches. In the case of salt haying, the goal was to convert vegetation to Spartina patens and promote firmer peat that could more readily support livestock as well as wagons and other farm vehicles. For mosquito control, the purpose was to remove mosquito breeding areas.
Why are ditches a problem for salt marshes?
Ditches result in changes in the types of vegetation, lowered water table, increased oxidation (decomposition) of peat, subsidence (lowered elevation) and loss of open water habitat. By changing the way the water flows through the marsh, ditches cause natural tidal channels to fill in or become deeper and stratighter when incorporated into the ditch network. The end result is a conversion from "natural creek hydrology" to one of "ditch hydrology."
What can be done to restore the impacts of ditches?
Natural hydrology can be restored by "remediation" of the ditches. In other words, the ditches can be filled in (plugged or back filled) or converted to small pools of open water (pannes). The result is an increase in natural sedimentation and natural plant root growth. Over time, the ditches 'heal' by filling in and becoming contiguous with teh surrounding marsh.
