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


Data Release:
Heerspink, B., Kendall, A. D., Martin, S. L., Hyndman, D. W. (2026). Field Data and 
Sample Watershed Characteristics for a Repeated Synoptic Stream Water Chemistry 
Sampling in Michigan's Lower Peninsula, HydroShare,
http://www.hydroshare.org/resource/abed25adbcb443a0b5edd975912bbb0f


This archive contains the field data, supporting information, and python code 
used for all analysis and results presented in Heerspink et al., 2026. 
Specifically it contains:
	- 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.  
	- Physical and landscape characteristics summarized within the sample
	location watersheds. 
	- GIS files showing sample locations and sample point watersheds.
	- Python code used to format and analyze this data, and to create figures
	for the above referenced manuscript. 
	- Derived data and figures created by the python code. 

All of the files needed to run the python code, and re-create the 
analysis and figures presented in Heerspink et al., 2026 are included 
in this data release. Details on field data collection, sources of 
supporting data, and the analysis implemented in the including python code
are presented in the methods section of the above referenced manuscript. 

----------------------------------------------------------------------
Description of file structure: 

	The directories of this data release contain the data files, code and 
	figures presented in the manuscript.

	Descriptions of the content for each subdirectory are presented
	below. Brief descriptions of each file in each sub-directory are 
	also provided. For detailed information about the data included here
	or the analysis, please refer to the associated manuscript or contact
	the authors directly. 
	
	This sampling effort and manuscript were internally referred to as the 
	"Statewide" or "Statewide Nutrients" project, reflecting the effort 
	to collect, analyze and interpret data collected across Michigan's 
	Lower Peninsula. This naming convection is reflected in the names 
	of files contained within this data release. 
		
------------------------------------------------------------------------
Instructions:
	- To run the provided reference code
		1) Download all the folders in the repository to the 
		same level on your local machine 
		2) Install the project python environment using the provided 
		environment yaml file. 
			- For instructions on installing python and using and 
			environment file to setup a python environment, please 
			reference the following resources:
				- https://github.com/DOI-USGS/python-for-hydrology/tree/main/installation 
				- https://docs.conda.io/projects/conda/en/latest/user-guide/tasks/manage-environments.html 
		2) Open Spyder (included in the environment) or other python IDE,
		and change the working directory to the "Code" folder 
		3) Run the files in the following order:
			1) Statewide_Data_Formatting
			2) Statewide_Data_Analysis
			3) Statewide_Linear_Model
			4) Statewide_Final_Manuscript_Figures
	
------------------------------------------------------------------------
Folders and Files 

environment - Yaml python environment file. 
	
		
Synoptic_Stream_Chemistry_Metadata.xml - Formatted metadata with author and data attribution information. 

 Code/: -- Data processing and analysis codes 
    - Statewide_Data_Formatting - Formatting of observational and supporting data compiled 
	by project staff during and directly after sample collection in 2010-2011. 
	
	- Statewide_Data_Analysis - Statistical analyses of the water quality and watershed 
	characteristics data. These analyses form the basis for the manuscript results. 
	
	- Statewide_Linear_Model - Ordinary Least Squares (OLS) statistical model relating 
	watershed characteristics to observed water chemistry for all sample locations 
	across the three sampling events. 
	
	- Statewide_Final_Manuscript_Figures - code to create the content of the main body 
	and supplemental figures. To create the final manuscript figures, the authors combined 
	or formatted some of these figures using graphic design software. 

 Data/: -- Original and pre-processed data
	- Baseflow_Data.csv - Data for the October 2010 synoptic sampling campaign.
	
	- Snowmelt_Data.csv - Data for the March 2011 synoptic sampling campaign.
	
	- Summer_Rain_Data.csv - Data for the June 2011 synoptic sampling campaign.  
	
	- LP_Wide_SENSEMap_Sources.csv - Spatially explicit nutrient source estimates 
	from Hamlin et al., 2020 (https://doi.org/10.1029/2019JG005134) summarized
	for the sample watersheds. 
	
	- LP_Wide_Watershed_hydro_properties.csv - hydrologic properties summarized 
	for the sample watersheds.
	
	- NLCD_2006_reclassed_percentages.csv - 2006 NLCD Land Cover Classes 
	summarized by percent of total area for the sample watersheds. 
	
	- NLCD_2011_reclassed_percentages.csv - 2011 NLCD Land Cover Classes 
	summarized by percent of total area for the sample watersheds. 
	
	- Statewide_Data_Units.csv - Units for all types of collected data. 
	
	- Statewide_USGS_Flow_Sites.csv - Information on USGS streamflow gages 
	co-located with project sample locations. 
		- Note to users: The USGS Site I'd for these locations all start
		with a leading zero. Some applications like Microsoft Excel 
		automatically strip leading zeros. 
	
	- StatewideWatershedProperties.csv - Summarized static watershed properties
	for the sample point watersheds.

Derived_Outputs/: -- Outputs from the formatting and processing codes
	- HydroLCModel_SigParams.csv - Significant parameters from the combined 
	hydrology and land cover linear regression model. 

	- HydroLCModelData.csv - Statistical analysis summarizing results of the 
	combined hydrology and land cover linear model including R-squared, 
	adjusted r-squared, P-values and Moran's I. 
	
	- LandCoverModelData.csv - Statistical analysis summarizing results of the 
	land cover linear only model including R-squared, adjusted r-squared, 
	P-values and Moran's I. 

	- IonConcentrationSummaryStats.csv - summary statistics of major ions 
	across the three sampling events.
	
	- NutreintConcentrationSummaryStats.csv - summary statistics of nutrient
	species across the three sampling events.
	
	- Statewide_Derived_Data_Units.csv - units for the formatted or 
	analyzed data contained in the Derived_Outputs folder. 
	
	- StatewideLinearModel.h5 - HDF5 file with the outputs of the linear
	models and comparisons between the different models. 
	
	- StatewideSamplingData.h5 - HDF5 file containing the outputs of the 
	data formatting and data analysis codes.

	- StatewideSampleEvent8DayPrecip.csv - 8-day prior precipitation totals
	for the sample point watersheds across the three sampling events. 
	
	- StatewideWatershedPropertiesUpdated.csv - Updated, formatted version of the 
	watershed properties for the sample point watersheds. 
	
Paper_Figs_and_Tables:/ -- Formatted paper figures and tables for main body 
and supplemental. This folder will not be populated until the manuscript 
plotting code is run locally by a user. The resulting files are labeled by 
their corresponding figure number in the manuscript.


Shapefiles:/ -- GIS files related to sampling locations, all files in EPSG:3078
	- Michigan_LP_boarder_noIslands_MiGeoRef.shp - Municipal boarder of the State
	of Michigan's Lower Peninsula with no islands. 
	
	- Statewide_Sampling_Points_MiGeoRef.shp - Sampling location points for the three
	seasonal synoptic sampling events. 
	
	- Statewide_Sampling_Full_Sheds_MiGeoRef.shp - Sample point watersheds.