ABSTRACT:

A repeated synoptic sampling of stream chemistry and physical parameters (e.g. streamflow) in 64 Great Lakes tributaries across Michigan's Lower Peninsula was completed during three distinct hydrologic conditions: spring snowmelt, post-planting summer rainfall, and fall low-flows. Data from this sampling effort, along with physical properties of the sample watershed were analyzed to understand how landscape characteristics and hydrologic processes controls seasonal variations in stream nutrient concentrations. The methods and results of these analyses are presented in the associated publication: "Heerspink, B.P., Kendall, A.D., Martin, S.L., and Hyndman, D.W. 2026. Seasonally variable relationships between landscape characteristics, hydrology, and stream nutrient concentrations revealed through strategic synoptic sampling. Journal of Hydrology. https://doi.org/10.1016/j.jhydrol.2026.135975".

This archive contains the field data, supporting information, and python code used for all analysis and results presented in the above referenced paper. Specifically, it contains:
1) Water quality and streamflow and other physical data collected during a repeated synoptic sampling of streams across Michigan's Lower Peninsula between October 2010 to June 2011.
2) Physical and landscape characteristics summarized within the sample location watersheds.
3) GIS files showing sample locations and sample point watersheds.
4) Python code used to format and analyze this data, and to create figures for the above referenced manuscript.

Field data collection, sample analysis, and compilation of supporting data (e.g. sample point watershed land cover) are described in the methods section of Heerspink et al., 2026.