Reservoir · Washington · United States · USGS NWIS
Alder Reservoir
91.4% full
Capacity
264.58 hm³
Volume stored
242 hm³
Coordinates
46.802°N, 122.311°W
Last updated
2026-07-16
Current fill
91.4%vs 7 days ago
-1.0%losing
vs 1 year ago
+15.3%year-over-year
7-day trend
→stable
Data source: USGS National Water Information System (NWIS) — daily reservoir storage volume. Capacity is the design (normal full-pool) capacity from the US National Inventory of Dams (NID); fill % = current volume ÷ design capacity. Last reading: 2026-07-16.
Catchment Weather
Past 30 days + 14-day forecast · Open-Meteo
Satellite imagery: Esri, Maxar, Earthstar Geographics. Map: Esri, HERE, Garmin, © OpenStreetMap contributors. 46.802, -122.311 · Open in Google Maps
About Alder Reservoir
As of July 16, 2026, Alder Reservoir is filled to 91.4% of its total capacity, holding roughly 242 hm³ of water out of a maximum 265 hm³. At this level the reservoir is high.
Over the most recent week on record the fill level has held broadly steady (-1.0 pts), and it is 15.3 points above its level on the same date a year earlier.
Across the readings we hold for Alder Reservoir — 1326 data points between August 14, 2022 and July 16, 2026 — the level has ranged from a low of 41.6% (October 24, 2025) to a high of 98.3% (June 15, 2024). On average the reservoir is fullest around June and at its lowest around October.
It is operated by USGS primarily for multiple purposes. It lies within the Washington basin at 46.802°N, 122.311°W.
Key facts
- Current fill level
- 91.4%
- Water stored
- 242 hm³
- Total capacity
- 265 hm³
- 7-day change
- ▼ 1.0 pts
- Year-on-year
- ▲ 15.3 pts
- Primary use
- Multipurpose
- River basin
- Washington
- Operator
- USGS
- Coordinates
- 46.802°N, 122.311°W
- Last updated
- July 16, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 16 Jul 2026 | 91.4% | 242 |
| 15 Jul 2026 | 91.4% | 242 |
| 14 Jul 2026 | 91.5% | 242 |
| 13 Jul 2026 | 91.7% | 243 |
| 12 Jul 2026 | 92.0% | 243 |
| 11 Jul 2026 | 92.2% | 244 |
| 10 Jul 2026 | 92.3% | 244 |
| 9 Jul 2026 | 92.4% | 244 |
| 8 Jul 2026 | 92.6% | 245 |
| 7 Jul 2026 | 92.6% | 245 |
| 6 Jul 2026 | 92.7% | 245 |
| 5 Jul 2026 | 92.9% | 246 |
Frequently asked questions
What is the current water level of Alder Reservoir?
As of July 16, 2026, Alder Reservoir is at 91.4% of its capacity, holding approximately 242 hm³ of water, according to USGS NWIS data.
Is Alder Reservoir reservoir full?
No. As of July 16, 2026, Alder Reservoir is high at 91.4% of its capacity, so it is not full.
Is the water level at Alder Reservoir rising or falling?
The level at Alder Reservoir has been broadly stable over the latest week on record (-1.0 points).
How much water can Alder Reservoir hold?
Alder Reservoir has a total capacity of 265 hm³.
Where is Alder Reservoir reservoir located?
Alder Reservoir is located in Washington, United States, within the Washington basin (coordinates 46.802°N, 122.311°W).
What is Alder Reservoir used for?
Alder Reservoir is used primarily for multiple purposes, and is managed by USGS.