PERMANENT_ID		ID number for each lake that corresponds to high-resolution USGS National Hydrography Dataset
lake.name			name of each lake (standardized across all files)
date				date of measurement in YYYY-MM-DD format
year				year of measurement, four digit format
month				month of measurement, values range 5-9
day					day of measurement, values range 1-31
Z.max				maximum depth at sample site (m)
sample.depth		depth of water sample (m); integrated water sample taken from surface down to sample depth
sample.layer		Ye = epi, N = not stratified	
TotalP.ug.L			total phosphorus in ug/L
MRP.ug.L			molybdate-reactive phosphorus in ug/L
TFP.ug.L			total filterable phosphorus in ug/L
TotalN				total nitrogen in mg/L
chl.a.ug.L			chl-a concentration in ug/L
Fe					iron in mg/L