My detailed data sets for the Raccoon and Des Moines Rivers at Des Moines go back to 1974 and 1982, respectively. Here are some interesting nuggets from that data:
| Largest Nitrate-N Loading Years | |||
| Raccoon | Des Moines | ||
| year | N Load (kg) | Year | N Load (kg) |
| 2015 | 47,456,365 | 1991 | 68,891,857 |
| 1993 | 36,559,570 | 2016 | 65,197,500 |
| 1991 | 35,032,826 | 1993 | 65,193,560 |
| 2016 | 33,442,173 | 2015 | 50,554,633 |
| 2010 | 31,752,718 | 1984 | 48,170,390 |
| 2007 | 31,445,480 | 1999 | 47,259,680 |
| 1999 | 30,326,304 | 2010 | 45,514,501 |
| 1984 | 30,241,192 | 2007 | 44,537,829 |
| 1983 | 29,720,481 | 1992 | 43,067,226 |
| 1998 | 27,109,932 | 1983 | 42,305,864 |
| Smallest Nitrate-N Loading Years | |||
| Raccoon | Des Moines | ||
| year | N Load (kg) | Year | N Load (kg) |
| 1977 | 256,146 | 1989 | 852,083 |
| 2000 | 1,099,153 | 1988 | 4,014,574 |
| 1981 | 1,136,409 | 2000 | 5,073,673 |
| 1989 | 1,514,568 | 2012 | 5,086,696 |
| 2012 | 2,332,742 | 1987 | 12,498,792 |
| 1988 | 3,273,469 | 2002 | 13,307,778 |
| 1985 | 4,721,665 | 1990 | 13,442,047 |
| 1976 | 5,423,966 | 1985 | 14,218,439 |
| 1980 | 6,093,000 | 1996 | 18,212,045 |
| 1994 | 6,814,386 | 1997 | 18,490,627 |
| Largest Average Nitrate-N Concentration Years | |||
| Raccoon | Des Moines | ||
| year | N Conc (mg/L) | Year | N Conc (mg/L) |
| 2015 | 11.72 | 2015 | 9.89 |
| 2002 | 9.87 | 2016 | 9.64 |
| 1979 | 9.72 | 1992 | 8.89 |
| 1992 | 9.26 | 1991 | 8.70 |
| 2007 | 9.13 | 2007 | 7.89 |
| 2016 | 9.07 | 2006 | 7.70 |
| 1991 | 8.54 | 2002 | 7.51 |
| 1978 | 8.48 | 2005 | 7.42 |
| 2006 | 8.17 | 1999 | 7.24 |
| 1998 | 7.76 | 1995 | 7.09 |
| Smallest Average Nitrate-N Concentration Years | |||
| Raccoon | Des Moines | ||
| year | N Conc (mg/L) | Year | N Conc (mg/L) |
| 1977 | 0.58 | 1989 | 1.46 |
| 2012 | 2.34 | 2012 | 2.42 |
| 1981 | 2.52 | 1988 | 3.29 |
| 2000 | 2.89 | 2000 | 3.31 |
| 1976 | 2.98 | 1997 | 4.66 |
| 1989 | 2.98 | 2011 | 4.67 |
| 1975 | 3.68 | 2013 | 4.97 |
| 1988 | 4.56 | 1994 | 5.17 |
| 1974 | 4.72 | 2008 | 5.26 |
| 1985 | 4.75 | 2009 | 5.39 |
| Largest Nitrate-N Load Months | |||
| Raccoon | Des Moines | ||
| year | N Load (kg) | Year | N Load (kg) |
| Jun-13 | 12,398,580 | Jun-91 | 18,978,427 |
| Jun-15 | 10,435,396 | May-91 | 18,326,453 |
| May-13 | 9,426,514 | Jul-93 | 18,290,586 |
| Jun-08 | 9,103,654 | Jun-13 | 15,158,386 |
| May-91 | 8,768,826 | May-99 | 13,097,714 |
| May-16 | 8,740,426 | Jun-01 | 12,269,743 |
| May-07 | 8,726,000 | May-16 | 12,132,889 |
| Apr-99 | 8,663,559 | May-13 | 11,401,836 |
| Jul-93 | 8,516,596 | Jun-99 | 11,219,770 |
| Dec-15 | 8,486,714 | Jun-08 | 11,181,267 |
| Smallest Nitrate-N Load Months | |||
| Raccoon | Des Moines | ||
| year | N Load (kg) | Year | N Load (kg) |
| Jun-77 | 357 | Dec-89 | 5189 |
| Jul-77 | 386 | Feb-13 | 6735 |
| May-77 | 680 | Jan-89 | 8016 |
| Sep-12 | 829 | Nov-89 | 8673 |
| Oct-12 | 1168 | Jan-13 | 12,364 |
| Aug-12 | 1417 | Oct-89 | 12,578 |
| Oct-76 | 1648 | Jan-12 | 13,351 |
| Sep-05 | 2293 | Dec-13 | 14,936 |
| Oct-05 | 2423 | Dec-12 | 14,991 |
| Oct-03 | 2424 | Feb-89 | 15,205 |
| Days with Highest Nitrate-N Concentration | |||
| Raccoon | Des Moines | ||
| year | N (mg/L) | Year | N (mg/L) |
| 5/8/2013 | 24.4 | 5/17/2013 | 18.6 |
| 11/15/1979 | 22.0 | 5/10/2013 | 18.5 |
| 5/7/2013 | 21.9 | 5/16/2013 | 18.4 |
| 5/13/2013 | 21.4 | 5/11/2013 | 18.4 |
| 5/14/2013 | 21.4 | 5/15/2013 | 18.3 |
| 6/14/2013 | 21.2 | 5/13/2013 | 18.2 |
| 5/15/2013 | 21.1 | 5/14/2013 | 18.0 |
| 5/26/2013 | 21.1 | 5/9/2013 | 17.9 |
| 5/12/2013 | 21.0 | 5/18/2013 | 17.7 |
| 11/27/1979 | 21.0 | 5/12/2013 | 17.6 |
| Days with Largest Nitrate-N Load | |||
| Raccoon | Des Moines | ||
| year | N Load (kg) | Year | N Load (kg) |
| 6/15/2013 | 891,628 | 6/10/1991 | 837,946 |
| 5/28/2013 | 831,469 | 6/11/1991 | 798,649 |
| 6/15/2015 | 766,411 | 6/16/1991 | 753,432 |
| 6/25/2015 | 751,348 | 6/17/1991 | 746,810 |
| 6/1/2013 | 690,639 | 6/18/1991 | 736,640 |
| 6/16/2013 | 681,671 | 6/9/1991 | 734,977 |
| 5/31/2013 | 681,367 | 6/12/1991 | 720,287 |
| 6/2/2013 | 670,633 | 6/20/1991 | 700,066 |
| 5/29/2013 | 644,484 | 6/13/1991 | 699,853 |
| 6/3/2013 | 641,876 | 6/19/1991 | 693,082 |
These next two graphs show the average nitrate-N concentration and load with calendar day (DOY-day of year) over the period of record for each river.
