Monday, May 1, 2017

First Quarter nitrate levels in the Raccoon and Des Moines Rivers (at Des Moines) were above average in 2017 compared to the historical record. First quarter Raccoon nitrate-N concentration was 16th highest out of 43 years (1977-present), while total load was 8th highest. In an average year, 16% of the Raccoon N load occurs in the 1st quarter. In 2015, which was the biggest loading year ever for the Raccoon, only 6.7% of the annual load occurred in the 1st quarter.

For the Des Moines River, average concentration was 10th highest out of 36 years (1982-present) while load was 4th highest. In an average year, 13% of the Des Moines R. N load occurs in the first quarter.

Elevated river discharge was driving higher loads in 2017. First quarter Raccoon discharge was 8th highest while Des Moines R. discharge was 5th highest in the respective historical records where nitrate data is available.

Four graphs showing the 1st Quarter nitrate loads of 2017