Calgary water,
measured against its own ceilings.

Total water withdrawn from the Bow and Elbow rivers each year. Annual withdrawals have stayed in a narrow band since the late 1990s. Two reference lines are shown:

• ■ Provincial licence (Bow): ~460,000 ML/yr — the legal upper bound on diversion.
• ■ Plan operational cap:233,000 ML/yr through 2040 — the Water Efficiency Plan’s self-imposed ceiling, set below licence to stay within river-ecology limits during low-flow years.

Treatment-plant capacity is shown on the daily chart below, where it’s the binding ceiling (plants are rated daily, not annually).

Annual river withdrawals divided by Calgary’s population, in litres per resident per day. Calgary went from 616 L/resident/day in 1997 to 389 L/resident/day in 2023— a 37% reduction while population grew from ~790,000 to ~1.42 million. The dashed reference line shows the City’s separately published 2023 per-capita demand figure (356 L/p/d), which is lower because it excludes water resold to regional customers and uses a different population denominator.

Civic census stops in 2019; 2020–2022 are absent because no comparable City estimate was published. The 2023 point uses the April 1, 2023 estimate from the Spring 2024 Population Outlook.

Total daily water demand from the City’s public Climate & Environment dashboard, January 2024 onward. Background shading marks Calgary summer (June–September, orange) and winter (December–February, blue) so the seasonal swing is visible at a glance. Four reference lines overlay the demand curve — two true daily ceilings, two annual ceilings shown as daily-average equivalents (annual figure ÷ 365) so they can share the axis:

• ■ Licence (daily avg): 1,260ML/day — Calgary’s Bow River licence (460k ML/yr) shown as a daily average. Annual ceiling.
• ■ Plant capacity: 950 ML/day (Bearspaw 550 + Glenmore 400 rated post-upgrade). True daily ceiling.
• ■ Plan peak-day target (2040): 908 ML/day — ~96% of plant capacity. True daily ceiling.
• ■ Plan annual cap (daily avg): 638ML/day — the Water Efficiency Plan’s 233k ML/yr ceiling shown as a daily average. Annual ceiling.

Peak observed in this dataset: 698 ML on 2025-06-09 — about 73% of plant capacity and 77% of the 2040 peak target.

Calgary system water broken down into end-use sectors and non-revenue water (NRW) — the standard utility category that covers physical pipe leaks, meter undercounting, and authorised-but-unbilled use like firefighting and mains flushing. The City’s public copy sometimes shortens NRW to “leaks”; the Plan’s engineering target is an Infrastructure Leakage Index of 3.0 by 2030, which measures the real-loss (true leak) component specifically.

Average daily single-family per-capita water use by season, 2010–2017. Summer is roughly 20% above winter for this dataset — the seasonal swing is what drives peak-day stress on the system, and it’s mostly outdoor watering rather than indoor fixtures.

A decomposition of the seasonal data: the winter bar represents essentially pure indoor use (outdoor watering doesn’t happen at −20°C), and the summer bar splits that same indoor baseline from the outdoor add-on. The outdoor portion is the variable component — what stage-based restrictions actually target. Indoor use is roughly constant year-round.

Estimate from City of Calgary single-family data, 2010–2017. Assumes indoor use is constant year-round; in practice it varies modestly. See artefact derivation for full methodology.

The Water Efficiency Plan’s 2027–2030 budget envelope is $354M–$420M total. The largest single line is the Accelerated Water Loss Program ($179M) — pipe replacement, leak detection, copper-lead service replacement, and similar infrastructure work. Advanced metering is $161M, the second-largest line. Programs and policies (the “rules” portion: outdoor schedule, rate design, education, business programs) total $12.5M of operating budget — about 3.5% of the plan.

Mean discharge of the Bow River at the Calgary gauge (ECCC station 05BH004), 1912–2024. Thin lines are individual years; thick lines are 10-year rolling means. Summer (Jul/Aug/Sep) is when the river runs lowest and demand runs highest — that’s the stress window the operational cap is designed for. Recent years like 2023 (summer mean 72 m³/s) have been notably low.

When Calgary has been at each restriction stage since the June 2024 Bearspaw South Feeder Main rupture. Two distinct events drove every Stage 3-4 period on this timeline: the 2024 rupture and follow-up repairs, and the March 2026 planned reinforcement work for the ongoing Bearspaw replacement.

Calgary’s outdoor water restrictions have four stages, each with a defined trigger and a distinct rule set. Stages 1–2 are targeted at outdoor watering; Stages 3–4 are emergency measures with broader prohibitions.