在美国西部，极端高温与偏弱冬季积雪已使夏季水风险上升。2026年2月与3月，科罗拉多州立大学研究员 Brad Udall 指出，温度异常与快速融雪让积雪在三周内从「不佳」变成「糟透」，原本应支持晚季河川水文的融雪补给已被耗损，部分科罗拉多河河段已仅剩涓流。科罗拉多河服务7州约4,000万人，其主要水库 Lake Powell 与 Lake Mead 也为超过2,500万人供电；Lake Mead 目前仅高于历史最低位17英尺（约5.2公尺）。

这种水文压力叠加长期流域政治争议。科罗拉多河流域内，饲料作物 alfalfa 用水仍为最大，超过沿河各城市合计。各州错过2026年2月期限，未能更新《1922科罗拉多河条约》，该条约本应在上、下游流域之间分水。美国内政部5月宣布应急措施以维持 Lake Powell 发电，模型显示可能影响 Lake Mead 输出并压缩下游供水。Udall 指出，上游州可能首次未达下游州需水要求，进而引发跨州诉讼；虽然美国尚未有城市到达 Day Zero，但风险已不再只是情境推演。

德州 Corpus Christi 是最接近临界的警讯。官方预估9月进入 Level-1 干旱紧急状态，条件为180天需求超过供给。至5月初，Choke Canyon Reservoir 与 Lake Corpus Christi 仅为7.4%与8.7%蓄水。市政已施行家庭用水限制并要求工业用户9月起减少25%；住户月均用水6,000加仑（约22,700公升），而 ExxonMobil–Saudi Basic Industries 联合工厂日耗水13.5百万加仑（约51,100立方公尺）。工业淡化计划估价超过10亿美元且被否决追加拨款（Greg Abbott）。官方与学界呼吁采用20年时程规划，因地下水有限、湖泊易受干旱冲击，气候驱动的稀缺正逼使七州、两国与4,000万以上人口面对政策结构重组。

Extreme heat and weak winter snowpack in the American West have raised summer water risk. In February and March, Colorado State University researcher Brad Udall said unusual temperatures and rapid melt moved the snowpack from poor to terrible within three weeks. Runoff that should sustain rivers later is now depleted, and some reaches of the Colorado River are down to a trickle. The river serves about 40 million people in seven states. Lake Powell and Lake Mead reservoirs also power electricity for over 25 million people; Lake Mead is now only 17 feet (about 5.2 m) above its record low.

The physical stress sits on top of a decades-long basin dispute. In the Colorado basin, alfalfa is still the largest water use, greater than all river cities combined. States missed the February deadline to update the 1922 Compact, which is meant to divide flow between upper and lower basins. In May, the U.S. Interior Department announced emergency actions to hold Lake Powell generation, and models warn this may cut Lake Mead output and downstream availability. Udall says the upper basin could fail, for the first time, to deliver required water to the lower basin, risking litigation. No city has reached Day Zero yet, but the risk is no longer only a theoretical scenario.

Corpus Christi, Texas, is the clearest near-term warning. Officials expect a Level-1 drought emergency by September, defined as 180 days with demand above supply. In early May, Choke Canyon Reservoir and Lake Corpus Christi were 7.4% and 8.7%. Household restrictions and a 25% industrial cut were ordered; average residential use is 6,000 gallons per month (~22,700 L), while the ExxonMobil–Saudi Basic Industries plant uses 13.5 million gallons per day (~51,100 m3). A proposed industrial desalination project was estimated above US$1 billion, and Governor Greg Abbott denied added funding. Experts urge a 20-year horizon because groundwater is finite, lakes are drought-prone, and climate-driven scarcity may force structural policy changes across seven states and 40+ million people.