Altnow Reservoir dam
Altnow Reservoir
Altnow Reservoir, located in Harney County, Oregon, is a privately owned irrigation reservoir designed by M.A. Palmer & Sons and completed in 1908. The reservoir has a dam height of 20 feet and a storage capacity of 122 acre-feet, with a surface area of 16.1 acres and a drainage area of 0.77 square miles. Its primary purpose is irrigation, drawing water from Warm Spring Creek to support agricultural activities in the surrounding area.
Despite its age, Altnow Reservoir has a low hazard potential and is not currently rated for its condition. The reservoir features a slide gate outlet structure and has a maximum discharge capacity of 183.94 cubic feet per second. The reservoir is state regulated by the Oregon Water Resources Department, with permitting, inspection, and enforcement measures in place to ensure its safe operation. While the last inspection date was in 2009, the reservoir is subject to regular inspections every six years.
Altnow Reservoir plays a vital role in supporting local agriculture in the Drewsey area, providing a reliable water source for irrigation purposes. With its earth dam construction and historical significance dating back over a century, the reservoir stands as a testament to the ingenuity and resourcefulness of early water management practices in Oregon. As water resource and climate enthusiasts, Altnow Reservoir serves as a reminder of the essential role that well-maintained reservoirs play in sustaining agricultural livelihoods and ecosystem health in arid regions.
Dam data reference
Condition Assessment
- Satisfactory
- No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
- Fair
- No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action.
- Poor
- A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency.
- Unsatisfactory
- A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
- Not Rated
- The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Hazard Potential Classification
- High
- Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
- Significant
- Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environmental damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
- Low
- Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
- Undetermined
- Dams for which a downstream hazard potential has not been designated or is not provided.
Plan around the weather
Same NOAA / yr.no feed Snoflo's iOS app uses. Watch the precipitation column on the meteogram -- rain on the basin upstream typically lifts inflow 24-72 hours later.
Next 5 days, hour by hour
Temperature line with weather symbols on top, snow + rain accumulation as columns, humidity as a dotted line.
5-day forecast table
Every 3 hours, broken out across temperature, snow, rain, humidity, and wind. Each cell is colour-coded relative to the column min/max.
| Time | Condition | Temp (°F) | Snow (in) | Rain (in) | Humidity (%) | Wind (mps) | Wind dir |
|---|---|---|---|---|---|---|---|
| Loading detailed forecast… | |||||||
15-day temperature & precipitation
Daily temperatures, snow, and rain projected over the next two weeks.
Nearby streamflow gauges
USGS streamgauges around Altnow Reservoir -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| North Fork Malheur River At Beulah Or | 1 cfs | → |
| Malheur R Be Warmsprings Res Nr Riverside Or | 0 cfs | → |
| John Day R At Blue Mtn Hot Spgs Nr Prairie City | 32 cfs | → |
| John Day River Near John Day | 68 cfs | → |
| Owyhee River Below Owyhee Dam Or | 158 cfs | → |
| Malheur River Below Nevada Dam Near Vale Or | 23 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Altnow Reservoir.
Boat launches
- Beulah Reservoir Ramp
- North Warm Springs
- North Point Boat Launch 1
- North Point Boat Launch 2
- Warm Springs Reservoir South Boat Ramp
- Middle Warm Springs
Campgrounds
- Chukar Park
- Crane Crossing
- Crane Creek Campground
- Little Crane
- North Fork Malheur Campground
- North Fork Malheur
Paddle runs
Track Altnow Reservoir in the Snoflo app
Save this dam as a favorite and get the local NOAA / yr.no forecast plus regional flow context wherever you are.
About Altnow Reservoir
Where does the data for Altnow Reservoir come from?
Structural and regulatory data come from the U.S. Army Corps of Engineers' National Inventory of Dams (NID). Weather forecast comes from NOAA / yr.no -- the same feed Snoflo's iOS app uses.
How often is the report updated?
NID structural data refreshes annually as the Corps publishes updated assessments. The weather forecast refreshes throughout the day.
What does the Low hazard rating mean?
The Corps of Engineers' hazard potential classification grades probable consequences if the dam fails: High = probable loss of human life; Significant = no probable loss of human life but possible economic loss / environmental damage; Low = no probable loss of human life, only minor economic / environmental losses. See the Dam Data Reference card above for the full definitions.
What's "% of normal"?
The current storage value compared to the historical average storage on this calendar day. 100% = right on average; values above 100% mean above-normal storage (wet year); values below mean below-normal (dry year or drought).
Can I get alerts when storage crosses a threshold?
Yes -- alerts are managed in the Snoflo iOS app. Favorite this dam, set a threshold, and you'll get a push the moment conditions cross.
Other water bodies near here
Snoflo-tracked reservoirs and dams within driving distance of Altnow Reservoir.