The USGS, in cooperation with the USEPA, is developing a water-quality model, called SPARROW (Spatially Referenced Regressions on Watershed Attributes), to assist in the development of regional nutrient water-quality criteria and total maximum daily loads (TMDL) for streams in New England. SPARROW is a spatially detailed, statistical model that relates concentrations of phosphorus and nitrogen (nutrients) in streams to pollution sources and watershed characteristics. The SPARROW model for New England will refine a national model developed by the USGS in the early 1990s. The model provides estimates of nutrient concentrations, yields, and transport in watersheds.

The New England SPARROW model is the first SPARROW model built upon the 1:100,000-scale National Hydrography Dataset (NHD). There are 42,000 NHD stream reaches and associated watersheds (figure 1) in the model. The NHD watersheds average less than 2 square miles in size and were generated using the National Elevation Database (NED) and Natural Resources Conservation Service watershed boundary data.

The New England SPARROW model will provide estimates of the amount of in-stream nutrients based on data pertaining to point and non-point contaminant sources and watershed characteristics such as slope, streamflow, stream density, percent wetlands, and land use. Information about point sources will be derived from databases such as the USEPA's Permit Compliance System; information about nonpoint sources will be derived from data such as fertilizer use, livestock wastes, and atmospheric deposition.

The New England SPARROW model will provide estimates of phosphorus and nitrogen concentrations and yields, sources, and downstream movement of nutrients by watershed. This information will be used to

• understand ranges in nutrient levels in surface waters
• identify the environmental factors that affect nutrient levels in streams
• define the variation of nutrient level by ecoregion, watershed, and other environmental settings, and
• evaluate management options for reducing nutrient loads to achieve water-quality goals.

 

--Richard Moore (603) 226-7825 or rmoore@usgs.gov

Back to Table of Contents