Chesapeake Bay Pollution Graphs
Graph 1: Total amount of nitrogen pollution into the bay.
Year
Nitrogen load (millions of
pounds)
1985
369.8
2009
2011
282.7
267
Graph 2: Amount of nitrogen pollution (millions of pounds) into the bay by different sources.
Year
Agriculture
Urban Runoff
Wastewater &
Septic Systems
Sewer Overflow
1985
141.8
34.2
89.2
5.2
2009
113.8
39.7
52.2
8.4
2011
108.7
40.1
44.4
8.3
Atmosphere
99.4
68.6
65.9
Graph 3: Total amount of phosphorus (millions of pounds) into the Bay.
Year
Phosphorus (millions of pounds)
1985
25.6
2009
19.2
2011
18.3
Graph 4: Amount of phosphorus (millions of pounds) from different sources
Year
Agriculture
Urban Runoff
Wastewater & Sewer
Overflow
1985
11.0
2.8
10.0
2009
10.6
3.0
4.0
2011
10.4
3.0
3.1
Atmosphere
1.73
1.70
1.69
Analysis Questions:
1. Looking at graph #1, what is the general trend in the amount of nitrogen going into the Bay?
2. Looking at graph #3, what is the general trend in the amount of phosphorus going into the Bay?
3. What do you think could be responsible for the trends you noticed in nitrogen and phosphorus pollution?
4. Looking at graphs #2 and #4, what happened to the amount of nitrogen and phosphorus pollution coming from
urban (cities) runoff?
5. Why do you think urban runoff seems to have an opposite trend from the other sources?
6. Why do you think that the nitrogen pollution coming from agriculture (farming) and wastewater and sewage
have dropped so significantly?