Johnson Lake Dam dam
Johnson Lake Dam
Johnson Lake Dam, located in Zavala, Texas, on Chaparrosa Creek, is a privately owned Earth dam primarily used for irrigation purposes. Built in 1966 by LOCKWOOD ANDREWS & NEWMAN, the dam stands at a height of 21 feet and has a storage capacity of 420 acre-feet. Despite being a non-federally regulated structure, the dam has undergone state inspections and permitting to ensure its safety and functionality.
With a spillway type of "None" and a hazard potential of "Not Available," Johnson Lake Dam presents a unique profile in terms of risk assessment. Even though its condition has not been rated, the dam is categorized as having a high risk level (2). Emergency action plans and inundation maps have not been prepared for this structure, raising potential concerns in the event of a dam failure. However, the dam has not been modified since its completion, indicating a stable operational history.
Despite its lack of federal oversight, Johnson Lake Dam serves as a vital resource for irrigation in the region. As climate change continues to impact water resources, the management and monitoring of dams like Johnson Lake become increasingly important to ensure the safety and sustainability of water supplies for agriculture and other purposes. It is essential for private dam owners to collaborate with state agencies to implement best practices for dam safety and emergency preparedness to mitigate risks and protect surrounding communities.
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 Johnson Lake Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Nueces Rv Bl Uvalde | 0 cfs | → |
| Leona Rv Nr Uvalde | · | → |
| Nueces Rv Nr Asherton | 12 cfs | → |
| Frio Rv Bl Dry Frio Rv Nr Uvalde | · | → |
| Nueces Rv At Laguna | 91 cfs | → |
| Las Moras Spgs Dws Of Pool At Brackettville | 10 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Johnson Lake Dam.
Track Johnson Lake 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.
About Johnson Lake Dam
Where does the data for Johnson Lake 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 Not Available 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 Johnson Lake Dam.