Marsh Lake dam
Marsh Lake
Marsh Lake, also known as Mason Lake, is a private reservoir located in Pony, Montana, within the Cataract Creek watershed. Managed by the USDA NRCS, this irrigation dam was completed in 1956 and stands at a height of 8 feet with a length of 314 feet. The reservoir has a storage capacity of 68 acre-feet, primarily used for agricultural purposes in the surrounding area.
Despite its low hazard potential, Marsh Lake plays a crucial role in water resource management in the region, providing a reliable water source for irrigation. The dam is primarily composed of earth materials and is regulated by the Forest Service. With a maximum discharge of 54 cubic feet per second, the reservoir serves as a vital resource for maintaining water supply and supporting agricultural activities in Madison County, Montana.
As a key infrastructure for water management, Marsh Lake serves as a testament to the importance of sustainable water resource practices in the face of changing climate conditions. With its historical significance and ongoing role in supporting local agriculture, this private reservoir in Pony stands as a valuable asset in the region's water management efforts.
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 Marsh Lake -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Willow Creek Near Harrison Mt | 6 cfs | → |
| Jefferson River Near Twin Bridges Mt | 1,770 cfs | → |
| Ruby River Near Twin Bridges Mt | 31 cfs | → |
| Madison River Bl Ennis Lake Nr Mcallister Mt | 1,140 cfs | → |
| Madison River Ab Powerplant Nr Mcallister Mt | 230 cfs | → |
| Jefferson River Near Three Forks Mt | 1,670 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Marsh Lake.
Boat launches
- Mt 359 Jefferson County
- Us 287 Gallatin County
- Montana Highway 84 Madison County
- Warm Springs Day Use
- Power House Boat Launch
- Canaday Boat Launch
Campgrounds
- Potosi Campground
- Potosi
- Potosi Campground And Picnic Area
- Branham Lakes Campground And Picnic Area
- Branham Lakes
- Balanced Rock
Fishing spots
- Cataract Lake
- Brannan Lakes
- Branham Lakes
- Hot Springs Creek
- Cardwell Bridge Fishing Access Site
- Hells Canyon Creek
Paddle runs
More reservoirs
Track Marsh Lake 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 Marsh Lake
Where does the data for Marsh Lake 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 Marsh Lake.