Two linked line charts visualize water level readings over time for two well locations. The upper chart displays the full dataset, while the lower chart contains a brushable axis. Dragging the brush updates the upper chart’s x-axis domain to the selected time range, filtering both charts to that interval. The visualization uses d3.csv, d3.scaleTime, d3.scaleLinear, and d3.brushX to manage data loading, scaling, and interactive selection, rendering paths and circles as SVG elements.