trol of erosion and moderate applications of fertilizers,
pesticides, and herbicides. BMPs, however, require
willing farmers whose willingness is often directly proportional
to economic incentives, or to the potency of
the regulatory alternative (Young and Karkoski 2000).
Total maximum daily load, or TMDL, is a calculation
of the maximum amount of a pollutant that a waterbody
can receive and still meet water quality standards (EPA
1999). The U.S. Environmental Protection Agency has
recently published guidelines for establishing acceptable
nutrient criteria for different ecoregions of the
United States, recognizing the inherent variability in
local and regional availability of nutrients (EPA 2000).
To allow for this natural variation, phosphorus and nitrogen
water quality standards are established within
each region based on comparison with reference, or
minimally impacted, waters, or on a percentile of the
lowest-nutrient waters (Fig. 3). Once a standard is set,
management practices can be enacted that reduce inputs
of unwanted nutrients. Atmospheric deposition is an
additional large source of non-point pollution that
could be reduced through more stringent controls on
emissions of sulfur, nitrogen, metals, and organic toxins,
and application of more efficient technologies for
transportation and energy production (Driscoll et al.
2001).
trol of erosion and moderate applications of fertilizers,pesticides, and herbicides. BMPs, however, requirewilling farmers whose willingness is often directly proportionalto economic incentives, or to the potency ofthe regulatory alternative (Young and Karkoski 2000).Total maximum daily load, or TMDL, is a calculationof the maximum amount of a pollutant that a waterbodycan receive and still meet water quality standards (EPA1999). The U.S. Environmental Protection Agency hasrecently published guidelines for establishing acceptablenutrient criteria for different ecoregions of theUnited States, recognizing the inherent variability inlocal and regional availability of nutrients (EPA 2000).To allow for this natural variation, phosphorus and nitrogenwater quality standards are established withineach region based on comparison with reference, orminimally impacted, waters, or on a percentile of thelowest-nutrient waters (Fig. 3). Once a standard is set,management practices can be enacted that reduce inputsof unwanted nutrients. Atmospheric deposition is anadditional large source of non-point pollution thatcould be reduced through more stringent controls onemissions of sulfur, nitrogen, metals, and organic toxins,and application of more efficient technologies fortransportation and energy production (Driscoll et al.2001).
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