Maui Reservoir 21 dam
Maui Reservoir 21
Maui Reservoir 21, also known as Hc&S Reservoir 21, is a privately owned water storage facility located in Upper Paia, Maui, Hawaii. Completed in 1913, this earth dam stands at a height of 22 feet and has a storage capacity of 72.4 million gallons, primarily used for irrigation purposes. The reservoir covers a surface area of 6.9 acres and is fed by the Irrigation Gulch, serving as a vital resource for the surrounding agricultural lands.
Maintained and regulated by the Hawaii Department of Land and Natural Resources, Maui Reservoir 21 has a high hazard potential due to its size and location. Despite its age, the dam is in fair condition and undergoes regular inspections to ensure its structural integrity. With a moderate risk assessment rating, the reservoir plays a crucial role in water management in the region, supporting the local farming community and contributing to the sustainability of the area's water resources.
Situated within the Honolulu District and overseen by state authorities, Maui Reservoir 21 serves as a significant component of the water infrastructure in Maui County. With a history dating back over a century, this reservoir remains a key feature of the landscape, highlighting the importance of water conservation and management in the face of changing climate patterns. For water resource and climate enthusiasts, Maui Reservoir 21 offers a glimpse into the intersection of history, technology, and environmental stewardship in the Hawaiian Islands.
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 Maui Reservoir 21 -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Opana Tunnel Near Kailiili | 2 cfs | → |
| Honopou Stream Near Huelo | 5 cfs | → |
| Waikamoi Str Ab Res At Kula Pl Intake Nr Olinda | 1 cfs | → |
| Iao Stream At Kepaniwai Park Nr Wailuku | 87 cfs | → |
| Waihee River At Dam Near Waihee | 55 cfs | → |
| West Wailuaiki Stream Near Keanae | 47 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Maui Reservoir 21.
Campgrounds
- Kanaha Beach Park - Maui
- Hosmer Grove
- Hosmer Grove - Haleakala National Park - Maui
- Holua Dispersed - Haleakala National Park - Maui
- Hōlua Campsites
- Hōlua Campground
Track Maui Reservoir 21 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 Maui Reservoir 21
Where does the data for Maui Reservoir 21 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 High 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 Maui Reservoir 21.