SUNCOR ENERGY (USA) INC - COMMERCE CITY REFINERY

Exceptional drought arrives suddenly along the South Platte corridor

Denver County's drought conditions took a sharp turn in the first week of August. For most of the past twelve weeks the county held steady at 100% cumulative coverage across the Abnormally Dry through Extreme Drought categories, an already severe baseline that had at least stopped worsening. Then, in the week of August 4 through 10, the Exceptional Drought category, the worst classification the U.S. Drought Monitor tracks, jumped from 0% to 36.4% coverage. Because these categories are cumulative, that means more than a third of the county, including the stretch of the South Platte River corridor running through this ecosystem, is now sitting in the single most severe drought tier on record, layered on top of conditions that were already extreme. This matters for a river system already under seasonal stress, and it matters more given what sits along that same corridor. The Suncor Energy (USA) Inc. Commerce City refinery discharges to this stretch of the South Platte under its own permit, and if this sudden drought escalation has already reduced available flow, that would narrow the margin for diluting anything the plant releases, right as the river can least afford it. Current streamflow data for this stretch wasn't available to confirm whether flow has in fact dropped yet. Late summer already brings naturally lower flows and warmer water, both of which cut into dissolved oxygen just when aquatic insects are emerging and fish and invertebrates need it most. A jump this sudden and this deep, rather than a gradual slide, deserves close attention in the weeks ahead, both for what the drought itself does to the river and for how much less room it could leave to absorb whatever the refinery is putting into it.