Rivermatics

USGS Streamgage 12500450

Yakima River above Ahtanum Creek at Union Gap, WA

Yakima River above Ahtanum Creek at Union Gap, WA is USGS streamgage 12500450 in Washington, monitoring river discharge in hydrologic subbasin 17030003. It sits on the Yakima River, alongside 3 other gauges Rivermatics tracks on the same river. It drains a watershed of about 3,479 square miles. Discharge records at this site go back to 1966. Typical flow runs near 3,469.4 cfs in July and 4,114.3 cfs in April, with the higher of the two arriving in April. Rivermatics issues a daily machine-learned flow outlook for this gauge, reaching 14 days ahead.

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Gauge details

State
Washington
Drainage area
3,479 sq mi
Gauge elevation
943 ft
Subbasin (HUC-8)
17030003
Coordinates
46.53426, -120.46725
USGS site number
12500450
Records begin
1966-10-01 (60 years)
Rivermatics forecast
14-day flow outlook

14-day flow forecast

Based on observations through for Yakima River above Ahtanum Creek at Union Gap, WA. Each day carries a median estimate and the band the model expects the flow to fall within — not a single number to plan against. Forecasts are re-issued daily; see the live screen for the current outlook.

Forecast daily mean discharge in cubic feet per second, by date
Date Low p10 Expected p50 High p90 Range
2,178 2,261 2,310
2,145 2,247 2,314
2,103 2,241 2,351
2,117 2,252 2,383
2,099 2,244 2,374
2,068 2,228 2,359
2,046 2,215 2,352
2,024 2,205 2,352
2,004 2,196 2,352
1,997 2,193 2,358
1,987 2,191 2,363
1,979 2,187 2,366
1,980 2,188 2,372
1,970 2,185 2,373

All values in cubic feet per second (cfs). Estimates only — do not use them for navigation or for any safety, rescue, or emergency decision.

Typical flow by month

Long-term daily discharge percentiles from the USGS record (up to 60 years of data), averaged within each month. These describe the historical normal range — they are not a forecast and not today's reading.

Historical monthly discharge percentiles in cubic feet per second
Month Low p10 Typical p50 High p90 Range
January 1,085.7 2,272.6 5,826.8
February 1,310.7 2,467.6 6,955.2
March 1,521.3 2,977.7 7,378.4
April 2,093.3 4,114.3 8,838.3
May 2,821.9 5,341 11,683.9
June 2,798.7 4,537.7 10,134.3
July 2,835.5 3,469.4 4,976.8
August 2,741.6 3,320.6 3,764.2
September 2,139.3 2,587.7 3,056.3
October 1,197.5 1,720 2,290.6
November 1,043.3 1,722.3 3,416.7
December 1,098.4 1,877.1 5,553.2

All values in cubic feet per second (cfs).

Common questions

When does Yakima River above Ahtanum Creek at Union Gap, WA normally run highest?
May, on the long-term record. The median daily flow that month is about 5,341 cfs, against 1,720 cfs in October, the lowest month. These are historical normals for the date, not a forecast and not today's reading.
What is a normal flow for Yakima River above Ahtanum Creek at Union Gap, WA?
It depends on the month. In January, half of days historically fall near 2,272.6 cfs, with the middle 80% of days between 1,085.7 and 5,826.8 cfs. The month-by-month table on this page gives the full range.
How long has Yakima River above Ahtanum Creek at Union Gap, WA been measured?
Discharge records at USGS site 12500450 begin in 1966, about 60 years, covering roughly 9,200 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
Is there a flow forecast for Yakima River above Ahtanum Creek at Union Gap, WA?
Yes. Rivermatics trains a machine-learned model — a temporal-fusion transformer — on this basin's observed flows, weather, and snowpack, and issues a daily flow outlook reaching 14 days ahead: a median estimate inside a confidence band, not a single number to bet on. Every forecast is scored against days the model never trained on, and that track record is published on the live gauge screen. Open live conditions to see the current outlook.
Where is Yakima River above Ahtanum Creek at Union Gap, WA?
The gauge sits at 46.53426, -120.46725, in Washington, in hydrologic subbasin 17030003, at an elevation of about 943 feet, draining roughly 3,479 square miles.
Can I use Yakima River above Ahtanum Creek at Union Gap, WA data for flood or safety decisions?
No. Rivermatics provides estimates, not guarantees, and the readings and forecasts here may be delayed, inaccurate, or wrong. Do not use them for navigation or for any safety, rescue, or emergency decision. Check the National Weather Service and USGS directly, and use your own judgment.

Upstream and downstream on the Yakima River

Every gauge Rivermatics tracks on this river, ordered by drainage area — upstream first. See the Yakima River in full.

Other gauges in this subbasin