Johnson Dam No 1 dam
Johnson Dam No 1
Johnson Dam No 1, located in Tom Green County, Texas, was completed in 1904 and serves primarily for irrigation purposes along the Concho River. This privately owned gravity dam stands at a height of 9.4 feet and has a storage capacity of 241 acre-feet, providing essential water resources for agriculture in the region. The dam also serves secondary purposes such as fire protection, stock maintenance, and small fish pond support, making it a vital infrastructure for the local community.
Despite being unregulated by the state, Johnson Dam No 1 has a moderate risk assessment of 3, indicating a potential hazard that requires attention. The dam features an uncontrolled spillway with a width of 60 feet, allowing for excess water discharge during heavy rainfall events. With only one uncontrolled outlet gate, the dam's structural integrity and maintenance play crucial roles in ensuring its continued functionality and safety. The last inspection in 2014 revealed the dam to be in a condition that is not rated, highlighting the need for further assessment and potential upgrades to mitigate any risks.
As a historic landmark in the area, Johnson Dam No 1 stands as a testament to early water resource development in Texas. Its presence along the Concho River not only supports agricultural activities but also contributes to the overall ecosystem health by maintaining water levels and providing habitat for various species. With its rich history and ongoing importance, the dam serves as a reminder of the intricate relationship between water resources, climate, and human development in the region.
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 Dam No 1 -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Concho Rv At San Angelo | 4 cfs | → |
| Red Arroyo At S. Chadbourne St. Nr San Angelo | 2 cfs | → |
| Pecan Ck Nr San Angelo | · | → |
| North Concho Rv Nr Grape Creek | · | → |
| S Concho Rv Abv Twin Buttes Res Nr San Angelo | 9 cfs | → |
| Spring Ck Abv Twin Buttes Res Nr San Angelo | · | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Johnson Dam No 1.
Track Johnson Dam No 1 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 Dam No 1
Where does the data for Johnson Dam No 1 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 Dam No 1.