This example shows ground-water levels over time, with one color-coded line per well. The main chart displays the full time series, while a smaller context chart below it includes a brushed region that filters the data displayed in the main chart. Built with D3 v5, the visualization uses `d3.line`, `d3.nest`, `d3.brushX`, and `d3.scaleTime` to render the SVG. The data is loaded from a CSV file hosted on VizHub.