THE LAMOILLE WATERSHED AS A MODEL FOR STORM WATER NUTRIENT RUNOFF FROM DAIRY FARMS IN VERMONT

Storm water runoff from agricultural areas carries excess nutrients with it, which leads to dead zones in nearby lakes. Lake Champlain is the sixth largest lake in the United States and is facing issues related to excess nutrients thought to be from farms. One area not adequately addressed is manure management on farms, especially farms using manure pits with and without a containment wall. The runoff from three farms of each of these types of manure management were analyzed for nutrients before and after storm events. Four key analytes linked to nutrient runoff were analyzed from field samples: phosphorus, dissolved oxygen, nitrate, and ammonia.

The study took place in the Lamoille River watershed, Vermont, which feeds into Lake Champlain. Stream data was collected before and after rain events. The differences between before and after storm values, and between upstream and downstream values of all of the analytes were statistically significant. However, there was no significant impact of manure containment style (with or without a wall) on phosphorus, dissolved oxygen, nitrate, and ammonia.

Manure pit style had relativity low impact on the streams, suggesting that containment is not effective, or other factors caused the increase in nutrient levels. Soil erosion, manure spreading, and septic tanks may have contributed. Sites were selected away from houses and fields. Erosion was visible at some sites, but with no measurable difference from sites without visible erosion. The results of this study indicate that manure containment systems currently in place may not be effective in reducing nutrient input to Lake Champlain.