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Some interesting patterns have emerged from the first years of long-term monitoring:
- All sites with any human use have much higher nitrate and phosphate concentrations than the forested reference stream (Figures 2, 3 and 4).
- Among the small watersheds, urban and suburban watersheds have similar nitrate concentrations, much higher than the forested reference, but lower than the agricultural watershed (Figure 2).
- Nitrate concentrations decrease downstream along the Gwynns Falls (Figure 3). Phosphate concentrations decrease through the rural and suburban portions of the watershed, but increase at the urban end (Figure 4).
Figure 2. Nitrate concentrations in four small watersheds in the Baltimore metropolitan area from Fall 1998 - Summer 2000.
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Figure 3. Mean nitrate concentrations at forested reference and four longitudinal sampling sites along the Gwynns Falls from October 1998 - December 1999.
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Figure 4. Mean soluble reactive phosphate concentrations at forested reference and four longitudinal sampling sites along the Gwynns Falls from October 1998 - December 1999.
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