1) Choose from any of these hyper-surveilled storage reservoirs in the Pacific Northwest.
2) Excavate “teacup” basins in a plaza. Downscale their dimensions in proportion to the reservoirs selected in (1) so they will all fit within the installation site.
3) Ring the basin interior with concentric steps-cum-seats.
4) Hack into the servers of the U.S. Department of the Interior where the data on water levels at the reservoirs is collected and parsed. (Or does the bureau have an API?)
5) Re-network the flow of data from these real-world reservoirs, so that not only will the numbers get rendered into info-porn, they will also determine the water levels of your simulant reservoirs.