Overview
The following three figures and accompanying tables show the approximate change in nutrient and sediment loads to the Chesapeake Bay since 2009. Horizontal lines mark the 2017 and 2025 load reduction targets.
Figures 1 and 2 show that nutrient loads from agriculture and wastewater decrease from 2009 to 2016. Figure 1 and the accompanying table show that nitrogen loads from septic systems have shown an increase between 1985 and 2009, but show a slight decreased since 2009. Urban/Suburban runoff loads show little change in nitrogen, with fluctuations in more recent loads. Phosphorus and Sediment loads from urban/suburban land show a long-term decline.
Figure 1: Total Nitrogen Delivered to Chesapeake Bay
Figure 2: Total Phosphorus Delivered to Chesapeake Bay*
* Caution is warranted when interpreting the Phosphorus progress results. Two studies by the United States Geological Survey (USGS), released in 2013 and 2015, indicate increasing phosphorus trends on Maryland’s Eastern Shore. Based on these monitoring results and other available science, such as phosphorus saturation and transport in soils, EPA believes that the level of effort to manage phosphorus may increase and has advised Maryland to consider additional actions to manage phosphorus in its 2016-2017 milestones and Phase III WIP.
Figure 3: Total Sediment Delivered to Chesapeake Bay
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