The old line from Heraclitus says you can never step in the same river twice. The Columbia may be about to test that idea. As the 2026 water year winds toward its close, the early read on 2027 is shaping up to look remarkably like the year now ending from a runoff perspective, and that rhyme is the thread running through our latest PNW hydro work.

Start with the here and now. July has been unusually dry across the Northwest, and the hydro system has felt it. Even with a stout heat event parked over the region, the generation response has been muted, ticking up from 9.9 GW to 11 GW over a weekend before flattening out rather than pushing higher. Our latest forecast steped generation down in every remaining month of the water year, with the deepest cuts landing in August and September as unregulated water expectations for late summer soften. Figure 1 shows the July precipitation picture running well below normal with little relief in the ten-day forecast.

Figure 1 | July Month-to-Date and 10-Day Forecast Precipitation (Percent of Normal)

Zoom out to the full season and the story is better than the dry headlines suggest. Jan-Jul runoff at The Dalles has been locked in near 93 MAF since late June, and while that lands a touch below the long-run normal, it is a clear step up from the string of dry years before it. Figure 2 ranks the water year against history and shows 2026 finishing ahead of 2023, 2024, and 2025, even if it falls shy of an average year.

Figure 2 | NWRFC Unregulated Flows Water Rank, Jan-Jul Runoff at The Dalles

Which brings us to next year. The first ESP-driven look at the 2027 water year comes in right around 93.5 MAF, almost exactly where 2026 is set to finish. The total may rhyme, but the composition tells a more interesting story. 2026 was distributed unusually, with runoff concentrated up at Grand Coulee relative to Lower Granite. The 2027 forecast pulls that back toward normal, trimming the Grand Coulee contribution while lifting flows on the Snake at Lower Granite. Figure 3 lays the two side by side. Same river system but a different shape.

Figure 3 | 2027 Jan-Jul ESP Forecast Runoff, Grand Coulee vs. Lower Granite

For operators and traders, that redistribution matters as much as the headline volume, shifting where and when the water shows up across the system. Our PNW Hydro Enterprise product tracks all of it, from daily generation forecasts and unregulated flow updates to the ESP-driven outlook that frames the year ahead.

Follow the link to learn more about Energy GPS PNW Hydro Enterprise coverage, reach out to us at [email protected].

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