Dam Report

Hewitt Dam dam

Montana, USA Hewitt Lake Coulee Hazard Low
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Dam height
10ft
Hazard rating
Low
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Hewitt Dam -- None dam
Hewitt Dam None · Hewitt Lake Coulee
About this dam

Hewitt Dam

Hewitt Dam, located in Phillips County, Montana, is a federal-owned structure primarily managed by the Department of Interior Fish and Wildlife Service. Built in 1938, this Earth-type dam serves as a Fish and Wildlife Pond with a capacity of 3,250 acre-feet of water from the Hewitt Lake Coulee. The dam stands at a height of 10 feet and has a hydraulic height of 7 feet, with a length of 1,180 feet and a surface area of 459 acres.

Despite its low hazard potential, the dam's condition assessment in 2020 was rated as poor, indicating a need for maintenance and potential upgrades. The structure has a moderate risk level, with a history of modifications and inspections by the Fish and Wildlife Service. With a maximum discharge capacity of 6,240 cubic feet per second, the dam plays a crucial role in managing water resources for the surrounding area while also providing habitat for fish and wildlife. As a key component of the local ecosystem, Hewitt Dam serves as a focal point for water resource and climate enthusiasts interested in conservation efforts in Montana.

StateNone
River / streamHewitt Lake Coulee
NID IDMT00640
Owner typeFederal
Primary purposeFish And Wildlife Pond
Dam typeEarth
Year built1938
Dam height10 ft
Dam length1,180 ft
Max storage3,250 AF
Normal storage1,070 AF
Surface area459.0 ac
Drainage area17.4 sq mi
Hazard potentialLow
ConditionPoor
Last inspectionWed, 23 Sep 2020 00:00:00 GMT

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.
Detailed forecast

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.

Hourly detail

Next 5 days, hour by hour

Temperature line with weather symbols on top, snow + rain accumulation as columns, humidity as a dotted line.

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Deep dive

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.

TimeConditionTemp (°F)Snow (in)Rain (in)Humidity (%)Wind (mps)Wind dir
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Long-term outlook

15-day temperature & precipitation

Daily temperatures, snow, and rain projected over the next two weeks.

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Regional inflow

Nearby streamflow gauges

USGS streamgauges around Hewitt Dam -- inflows here typically show up in storage 24-72 hours later.

Around the water

Make a day of it

Boat launches, lakeside camping, fishing access, and other reservoirs near Hewitt Dam.

Track Hewitt Dam 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.

FAQ

About Hewitt Dam

Where does the data for Hewitt Dam 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.

More reservoirs

Other water bodies near here

Snoflo-tracked reservoirs and dams within driving distance of Hewitt Dam.

Premium feature

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Manage alerts in the Snoflo app

Custom alerts are configured in the iOS app -- favorite this dam, set a threshold, and you'll get a push the moment conditions cross.

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