Water Watch Review: 26 Days of Metro Rationing, by the Numbers

26 days into the San Juan metro water rotation: Carraízo up 139 cm, La Plata down 179 cm since August 8, on AAA’s own 5:00 AM charts. The numbers first, then what they add up to.

At a glance

Carraízo, day by day

Three reservoirs, one scale

What it adds up to

What changed the picture over these 26 days was one storm at the very end. Carraízo spent most of the window falling — 18 of 24 days down, including a −7 cm drop on August 18 — before 1.14 in of rain on September 1 produced a +172 cm jump the next morning, pushing it to 38.92 m and erasing the earlier decline for a net gain of 139 cm since the rotation began. Cidra barely moved on net, up just 4 cm to 400.17 m, but the same late rain lifted it three straight mornings and it now sits 1.80 m above the control line, on pace to reach the observación line in about 4 days if that rate holds — arithmetic, not a forecast. La Plata got rain too, 2.13 in in the final week, but it barely dented the slide: 23 of 24 days down, a steady −7.5 cm/day pace, and a net loss of 179 cm to 44.59 m. It remains 4.09 m above the control line, still falling.

Numbers from AAA’s Monitoreo Diario charts, read each morning for our reservoir board; rain from USGS gauges within 12 km of each reservoir (a proximity proxy, not a basin measurement). Rates and pace dates are arithmetic over the stored readings, not forecasts. The narrative is drafted by Claude from the computed figures and checked number-by-number against them before publishing.