Upper Midwest Environmental Sciences Center



Figure 4. | Nitrate plus nitrite concentrations (box-whiskers) in fall stratified random sampling and October mean discharge (dashed line) at Dam 8 in the Upper Mississippi River. Data from Pools 4, 8, and 13 are included in the nitrate concentration. Mean concentrations dropped steadily from 1993 to a low in 1996, but have increased since then. |
![]() |
Page Last Modified: April 17, 2018