Maui Reservoir 20 dam
Maui Reservoir 20
Maui Reservoir 20, also known as Hc&S Reservoir 20, is a privately owned water storage facility located in Haliimaile, Maui, Hawaii. Built in 1913, this Earth-type dam stands at a height of 42 feet and has a maximum storage capacity of 164.8 acre-feet. The reservoir primarily serves the purpose of irrigation, being fed by an irrigation ditch.
Despite its historical significance and essential role in supporting agricultural activities in the region, Maui Reservoir 20 poses a high hazard potential due to its poor condition assessment. With a moderate risk rating, there is a pressing need for maintenance and risk management measures to ensure the safety and functionality of this critical water resource infrastructure. The last inspection in August 2020 revealed the dam's deteriorating state, emphasizing the urgency for rehabilitation and emergency preparedness.
As a key component of Hawaii's water resource infrastructure, Maui Reservoir 20 requires attention and investment to address its aging infrastructure and mitigate potential hazards. With state regulation and inspection in place, stakeholders must collaborate to safeguard this vital reservoir for sustainable water management and climate resilience in Maui County.
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 20 -- 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 | → |
| West Wailuaiki Stream Near Keanae | 47 cfs | → |
| Waihee River At Dam Near Waihee | 55 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Maui Reservoir 20.
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 20 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 20
Where does the data for Maui Reservoir 20 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 20.