This animation shows the accumulation of water quality observations for each of the lakes in the LAGOS-NE database. For each year and lake, the cumulative count of in water quality observations to date is shown by color. The first field observation in the database was recorded in 1933 from Lake Pepin (WI/MN). The lake with the most data points across the time period is Lake Champlain (NY/VT/QC). Approximately 12,000 lakes have at least one observation and appear as points on this map. Another 39,000 lakes are included in LAGOS-NE that do not have water quality observations, but have a large range of GIS-derived ecological context variables and watersheds calculated.