Phosphorus Budget for Gull Lake, Michigan

In this report, we summarize measurements of the P budget of Gull Lake, comparing a recent year of measurements (2013–14) of tributary inflows and the outflow with similar measurements made for the P budgets compiled by Tague (1977) and Tessier (unpublished). Tessier’s unpublished data are included as Appendix B. The 2013–14 data do not represent as complete a budget as the two previous ones, but are useful to consider whether watershed inputs of P via tributary inflows are changing. Watershed inputs are a particular concern for the Gull Lake Quality Organization because of new confined animal feeding operations and the applications of manure on croplands within the Gull Lake watershed.