APPROPRIATE USE OF THE CLUE MODEL

As with other nitrogen loading models, including those of the Cape Cod Commission and Buzzards Bay Project, the CLUE model is most appropriate under the following conditions:

Soils: This model is designed for coastal watersheds where unconsolidated coarse-grained sediments predominate. In such watersheds, the contribution of groundwater flow exceeds that of surface water flow because little precipitation runs off the surface of the ground. Instead, precipitation easily seeps into the coarse sediments and travels as groundwater to the receiving waters. These conditions exist on Cape Cod, in southern New England, Long Island, and in other coastal areas.

Receiving Waters: This model is specifically applicable to shallow embayments for which a flushing rate or water residence time can be determined. Tidal exchange is a key factor determining flushing rate.

Land Use: The type of land use (residential, commercial, agricultural) affects the amount of nitrogen delivered to underlying groundwater, which in turn affects the amount of nitrogen entering the receiving waters of a particular watershed. The model is applicable to rural and suburban areas where waste disposal is primarily by on-site systems; that is, individual homes have septic systems. The model accounts for agricultural and recreational land uses. It does not incorporate industrial land use.

Under these conditions, CLUE can be a useful tool in understanding the effects of land-use decisions on estuarine ecosystems. It is the only model currently available for southern New England coastal regions that estimates effects of nitrogen loading on four key ecosystem components - algal blooms, eelgrass, susceptibility to low-dissolved oxygen conditions, and fish populations.