Watersheds Transporting Wastewater to Coastal Ocean

The model does not fully account for differences in land cover, watershed size, ecosystem processes, sanitation efficiency, and other biogeochemical processes. This may lead to overestimation of impacts in coastal ecosystems with slow-flowing water, and underestimation for areas with rapid flush times.

Data on the location of most septic systems and sewer outfalls were modeled not observed and did not include information on septic failure rates or permitted or accidental sewer overflow events. This adds uncertainty to the model, and potentially underestimates the impacts of nitrogen given the high rates of septic tank failure.

For treated nitrogen, the model may overestimate actual nitrogen removal rates by treatment plants, leading to underestimation of impacts in the model.