Boulder staff: municipal supply likely reliable through 2050 under most scenarios; severe climate stress could create gaps

Boulder water resources staff presented a municipal water supply briefing to the Environmental Advisory Board on Nov. 5, laying out sources, modeling assumptions to 2050 and next planning steps.

The presentation, delivered by the city's water resources manager, said most modeled futures — including optimistic, continued-trends and moderately stressed scenarios — provide a reliable supply for Boulder through 2050 under the city's existing reliability criteria. The city's system is supplied chiefly from two Boulder Creek watersheds (about two-thirds of treated supply) and from transmountain Colorado River projects managed through the Northern Colorado Water Conservancy District (about one-third), and is treated at two local plants before distribution, staff said.

"We want our water system to be reliable enough not to require any sort of water use restrictions" in most years, the presenter said, describing a reliability goal set in 1988 that aims to avoid restrictions roughly 95% of the time and allows outdoor restrictions in some years. Model runs included a 10% factor of safety in demand to account for outages and other unmodeled risks.

Why this matters

The Colorado Water Plan and basin-scale forecasts show growing uncertainty: the plan estimates a 500,000 to 800,000 acre-feet-per-year gap across the South…