2 Year Graph

Seasonal Variation Graph

Graph Details and Help

Water quality data is displayed as a scatter-plot with data from individual sampling events displayed by date, for the previous two- and ten-year periods. Data from all available sources are plotted together. Clicking on a graph will open a larger version of it. To view/download data older than ten years, or to view/download data from individual data source(s), click the "Download Data" icon or button.

The scale used is chosen to accommodate typical values for the water quality parameter being graphed. Units are shown on the y-axis and in the graph title.

Graphs are generated and stored in the Water Atlas database on a periodic basis using an automated process. The date when the graph was created is shown.

The Seasonal Variation Graph displays a statistical summary of data from all available data sources for the entire period of record. It is used to illustrate typical variation in the selected water quality parameter from month to month during the year. The diagram below shows how to read the graph:

The median value is shown. Although not specifically marked on the graph, the mean (average) value is midway between the 25th and 75th percentiles.

The "whiskers" indicate the range of the sample values; those that are outside pre-defined "Minimum" and "Maximum" values are excluded. Sample data less than the Minimum or greater than the Maximum are considered to be outliers and are not displayed on the graph.