Cook Reservoir (Wash) dam
Cook Reservoir (Wash)
Cook Reservoir, also known as Hochstein Upper, is a private water storage facility located in Oregon, specifically in Washington County. Managed by a private owner, this reservoir serves primarily for irrigation purposes, storing up to 14 acre-feet of water with a normal storage capacity of 13.6 acre-feet. Built in 1972, the earth dam stands at a height of 27.5 feet and spans 160 feet in length, with a hydraulic height of 22 feet.
Situated along the Tualatin River tributary, Cook Reservoir plays a crucial role in water resource management in the region, covering a surface area of 2.7 acres and having a maximum discharge capacity of 72.9 cubic feet per second. Despite its significant hazard potential, the dam has not been rated for its current condition. With a controlled outlet featuring Needle gates, the facility undergoes regular inspections every three years to ensure its structural integrity and compliance with state regulations. Although located near individual residences, the reservoir remains a key asset for agricultural water supply in the area.
Overall, Cook Reservoir serves as a vital component of the local water infrastructure, contributing to irrigation needs and water resource management in Washington County, Oregon. With its strategic location, substantial storage capacity, and essential role in supporting agricultural activities, the reservoir underscores the importance of sustainable water management practices in the face of changing climate conditions. As a state-regulated facility subject to inspection and enforcement by the Oregon Water Resources Department, Cook Reservoir remains a key player in ensuring water security and resilience in the region.
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 Cook Reservoir (Wash) -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Tualatin River Near Dilley | 110 cfs | → |
| Willamette River At Newberg | 10,800 cfs | → |
| Fanno Creek At Durham | 15 cfs | → |
| East Fork Dairy Creek Near Meacham Corner | 21 cfs | → |
| Fanno Creek At 56th Ave | 0 cfs | → |
| South Yamhill River At Mcminnville | 351 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Cook Reservoir (Wash).
Boat launches
- Crescent Park Greenway Hillsboro
- Cook Park
- Tualatin Community Park
- Dayton Boat Ramp
- San Salvador Access
- Sauvie Island Boat Ramp
Campgrounds
Track Cook Reservoir (Wash) 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 Cook Reservoir (Wash)
Where does the data for Cook Reservoir (Wash) 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 Significant 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 Cook Reservoir (Wash).