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Precipitation and Streamflow Data

Automated Local Evaluation in Real Time (ALERT)

The District operates and maintains a network of real-time sensors used to collect hydrometeorological data.  This network provides information to county personnel and other agencies about precipitation, stormwater runoff, and weather conditions affecting our regional watersheds.

Rain gageUsing radio telemetry, sensors report data in the National Weather Service Automated Local Evaluation in Real Time (ALERT) format.  This type of network is commonly referred to as an ALERT system.

ALERT system sensors are event driven and transmit data in real-time to base station computers at the District's office and the Tucson National Weather Service office. Event driven real-time transmission, means that transmission of data occurs immediately as data is collected at field sites.

Data collected by the ALERT system is used by the National Weather Service to assist in issuing flood watches and warnings and to ground-truth radar determined rainfall estimates.

Stream gageALERT data is important to the District in providing for public safety.  Data is collected primarily to detect situations that can lead to flooding.  Data is also useful in reconstructing storm events and thus is of interest to a wide range of public and private users. 

Click to view ALERT data Currently, the ALERT system includes 93 precipitation, 36 stream, and 4 weather station sites located in Pima and adjacent counties.

VIEW ALERT SENSOR DATA.  Data is provided for current and recent historical periods. 

The links below provide additional information about the District’s ALERT sensor network and the data collected.

About ALERT System Sensor Data

ALERT sensors are programmed to report in every 12 hours regardless if a change has occurred.  Data is sent to the base station using radio telemetry. 

Precipitation

All precipitation gauges measure rainfall depth in 1mm increments.  The base station computer which collects and reports the data uses the relation 1 mm=0.03937 inches to convert millimeters to inches.  Reported values are in inches.  Gauges used are tipping buckets and are programmed to report each tip.

Stream Gauges

Stream gauges measure depth (stage).  Reported values may not represent the actual depth of water at a stream gauge.  Caution should be used in making decisions based on reported stage information.

Sensors are surveyed to a local datum.  The majority of the sensors used to measure stage are fixed in place.  Initial stage reported is the elevation of the sensor above the most recently surveyed channel bed.  Sensors cannot measure the presence or absence of water below them.

Most stream channels have sand beds that can aggrade and/or degrade over time, depending on how much scour or deposition has taken place in any particular flow event.  Distance between the sensor and the channel bed may have changed since the most recent survey.

Stream gauge sensors are interrogated every 5 minutes and programmed to report on a change of 0.2 feet or 2.4 inches.  Reported values are in feet.

Data Errors

Automatic rain gauges are set to tip (measure) at 1mm increments.  If precipitation less that 1mm falls into the gauge, evaporation may dry the tipping bucket between storms, causing a loss in measurement. 

Wind can reduce precipitation catchment by creating turbulence around a rain gauge and catchment error increases as wind velocity increases.  A common observation during thunderstorms is that the rain appeared to be blowing sideways.  This can reduce the amount of precipitation that falls into a gauge. 

Other errors may be introduced by the effects of vandalism, gauge height, calibration errors, blockages caused by bugs, and the physical environment (trees and buildings) near the gauge.

ALERT System Station and Sensor Metadata

 

SENSOR # SITE NAME LONGITUDE LATITUDE ELEVATION SENSORS LOCATION
1010 Golder Ranch 32.545470 -110.875107 3440 P Horseshoe Bend Road in Saddlebrooke
1020 Oracle Ranger Station 32.585660 -110.785907 4660 P approximately 1.3 mile south of Oracle
1030 Oracle Ridge 32.532797 -110.756252 6420 P approximately 1.5 miles north of Rice Peak
1040 Dodge Tank 32.511915 -110.864191 3300 P Edwin Road 1.3 miles east of Lago Del Oro Parkway
1050 Cherry Spring 32.518079 -110.836966 4040 P approximately 1.5 miles west of Charouleau Gap
1060 Pig Springs 32.526091 -110.794823 4805 P approximately 1.1 miles northeast of Charouleau Gap
1070 Catalina State Park 32.445478 -110.876797 3310 P northeast corner of Catalina State Park
1080 Rancho Solano 32.564214 -110.847831 3378 P Cañada Del Oro Wash northeast of Saddlebrooke
1083 Rancho Solano 32.564214 -110.847831 3378 S Cañada Del Oro Wash northeast of Saddlebrooke
1085 Mt Lemmon 32.442642 -110.788513 9140 WS Mount Lemmon
1086 Mt Lemmon 32.442642 -110.788513 9140 WD Mount Lemmon
1090 Mt Lemmon 32.442642 -110.788513 9140 P Mount Lemmon
1091 Mt Lemmon 32.442642 -110.788513 9140 RH Mount Lemmon
1092 Mt Lemmon 32.442642 -110.788513 9140 T Mount Lemmon
1094 Mt Lemmon 32.442642 -110.788513 9140 BP Mount Lemmon
1100 Golder Ranch Bridge 32.478076 -110.898851 2959 P Cañada Del Oro Wash at Golder Ranch Road
1103 Golder Ranch Bridge 32.478076 -110.898851 2959 S Cañada Del Oro Wash at Golder Ranch Road
1110 Coronado Camp 32.523153 -110.782659 4400 P Cañda Del Oro Wash 0.3 miles south of Coronado Camp
1114 Coronado Camp 32.523153 -110.782659 4400 S Cañda Del Oro Wash 0.3 miles south of Coronado Camp
1130 Samaniego Peak 32.468312 -110.817243 7500 P Samaniego Peak on Samaniego Ridge
1140 Dan Saddle 32.481245 -110.749031 6888 P Dan Saddle on Oracle Ridge
1200 CDO at Ina 32.335469 -111.042033 2247 P Cañada Del Oro Wash at Ina Road
1203 CDO at Ina 32.335469 -111.042033 2247 S Cañada Del Oro Wash at Ina Road
1230 Oro Valley Public Works 32.373864 -110.982656 2560 P Calle Concordia at Calle El Milagro
1240 Moore at LaCholla 32.438198 -111.012223 2856 P Moore Road at La Cholla
1250 Pima Wash at Ina Road 32.337050 -110.962372 2646 P Pima Wash at Ina Road
1253 Pima Wash at Ina Road 32.337050 -110.962372 2646 S Pima Wash at Ina Road
1260 Big Wash near Rancho Vistoso 32.450036 -110.945805 2826 P Big Wash near Rancho Vistoso Boulevard
1270 Cañada Del Oro at Oracle Rd 32.412587 -110.942098 2628 P Cañada Del Oro Wash near Oracle Road
1273 Cañada Del Oro at Oracle Rd 32.412587 -110.942098 2628 S Cañada Del Oro Wash near Oracle Road
1274 Big Wash near Oracle Rd 32.412587 -110.942098 2628 S Big Wash near Cañada Del Oro Wash
2020 Park Tank 32.262265 -110.546492 5043 P Redington Pass, 0.8 miles south of Park Tank
2030 Italian Trap 32.285166 -110.563500 4080 P Redington Pass, 0.7 miles east southeast of Italian Trap Tank
2040 White Tank 32.305340 -110.571542 4398 P Redington Road near White Tank
2050 Ranch Road 32.309893 -110.606933 4300 P Bellota Ranch Road near Redington Road
2070 Chiva Tank 32.267897 -110.606975 3769 P Tanque Verde Wash 0.5 miles south of Chiva Tank
2073 Chiva Tank 32.267897 -110.606975 3769 S Tanque Verde Wash 0.5 miles south of Chiva Tank
2080 Alamo Tank 32.280311 -110.635852 3950 P Redington Road near Alamo Well
2090 Tanque Verde Guest Ranch 32.245796 -110.682772 2719 P Tanque Verde Wash at Tanque Verde Guest Ranch
2093 Tanque Verde Guest Ranch 32.245796 -110.682772 2719 S Tanque Verde Wash at Tanque Verde Guest Ranch
2100 Swan at Camino del Pantera 32.299498 -110.892906 2662 P Swan Road at Calle del Pantera
2109 Tanque Verde TV Road 32.257030 -110.820181 2514 S Tanque Verde Wash at Tanque Verde Road
2110 Tanque Verde TV Road 32.257030 -110.820181 2514 P Tanque Verde Wash at Tanque Verde Road
2120 Tanque Verde Sabino Bridge 32.265287 -110.841530 2478 P Tanque Verde Wash at Sabino Canyon Road
2123 Tanque Verde Sabino Bridge 32.265287 -110.841530 2478 S Tanque Verde Wash at Sabino Canyon Road
2150 White Tail 32.413105 -110.731905 8170 P Catalina Highway 0.8 miles west of Palisade Ranger Station
2160 Sabino Dam 32.314635 -110.810856 2780 P Sabino Creek at USFS Dam
2163 Sabino Dam 32.314635 -110.810856 2780 S Sabino Creek at USFS Dam
2170 Ventana Sunrise 32.308747 -110.838977 2738 P Ventana Canyon Wash at Sunrise Road
2173 Ventana Sunrise 32.308747 -110.838977 2738 S Ventana Canyon Wash at Sunrise Road
2190 El Marah 32.279969 -110.802161 2556 P near El Marah on Bear Canyon Road
2200 AC Tanque Verde Road 32.250894 -110.766554 2613 P Agua Caliente Wash at Tanque Verde Road
2203 AC Tanque Verde Road 32.250894 -110.766554 2613 S Agua Caliente Wash at Tanque Verde Road
2210 Catalina Booster 32.276926 -110.772041 2688 P Houghton Road 0.1 miles south of Catalina Highway
2220 AC Park 32.282463 -110.792260 2760 P Agua Caliente Park
2230 Camino Rinconada 32.257085 -110.704023 2800 P El Camino Rinconado 0.5 miles north of Reddington Road
2240 Molino Canyon 32.311602 -110.711710 3640 P Mt Lemmon Highway near Mile Post 3
2280 Green Mountain 32.394576 -110.687284 7890 P Green Mountain
2290 Marshall Gulch 32.419874 -110.751911 7124 P Sabino Creek 0.6 miles south southeast of Marshall Gulch
2293 Marshall Gulch 32.419874 -110.751911 7124 S Sabino Creek 0.6 miles south southeast of Marshall Gulch
2300 Well D37 32.232037 -110.793188 2633 P Rosewood Street west of Harrison Road
2310 Well E23 32.222473 -110.750681 2811 P Rancho El Mirador north of Broadway Boulevard
2320 Well C51 32.233663 -110.879607 2522 P Beverly Avenue at Hawthorne Street
2330 Kolb Boosters 32.191277 -110.837976 2696 P Kolb Road at Golf Links
2350 Rillito near Dodge 32.271166 -110.911730 2387 P Rillito Creek near Dodge Boulevard
2353 Rillito near Dodge 32.271166 -110.911730 2387 S Rillito Creek near Dodge Boulevard
2360 Rillito La Cholla 32.302870 -111.011171 2264 P Rillito Creek at La Cholla Boulevard
2363 Rillito La Cholla 32.302870 -111.011171 2264 S Rillito Creek at La Cholla Boulevard
2369 Alamo 32.258710 -110.884129 2440 S Alamo Wash at Glenn Street
2370 Alamo 32.258710 -110.884129 2440 P Alamo Wash at Glenn Street
2380 Ruthrauff at La Cholla 32.294129 -111.011746 2270 P Ruthrauff Road at La Cholla Boulevard
2390 Finger Rock Wash Skyline 32.322809 -110.901395 2784 P Finger Rock Wash at Sunrise Road
2393 Finger Rock Wash Skyline 32.322809 -110.901395 2784 S Finger Rock Wash at Sunrise Road
4100 Manning Camp 32.207367 -110.554347 7930 P Manning Camp in the Rincon Mountains
4101 Manning Camp 32.207367 -110.554347 7930 RH Manning Camp in the Rincon Mountains
4102 Manning Camp 32.207367 -110.554347 7930 T Manning Camp in the Rincon Mountains
4104 Manning Camp 32.207367 -110.554347 7930 BP Manning Camp in the Rincon Mountains
4110 Rincon Creek 32.129671 -110.626022 3158 P Rincon Creek at X-9 Ranch
4113 Rincon Creek 32.129671 -110.626022 3158 S Rincon Creek at X-9 Ranch
4160 Well E8 32.162560 -110.819815 2804 P Irvington Road near Pantano Road
4180 Pantano Houghton 32.167486 -110.772661 2675 P Pantano Wash at Houghton Road
4220 Rancho del Lago 32.068346 -110.731023 3154 P approximately 1.8 miles northwest of Vail
4250 Pantano Vail 32.035953 -110.676761 3218 P Pantano Wash 1.5 miles southeast of Colossal Cave Road
4253 Pantano Vail 32.035953 -110.676761 3218 S Pantano Wash 1.5 miles southeast of Colossal Cave Road
4270 Salcido Place 32.039880 -110.495039 4376 P 6 miles north-northwest of Mescal
4280 Cienega Creek @ Interstate 10 31.985961 -110.567984 3582 P Cienega Creek at Interstate 10
4283 Cienega Creek @ Interstate 10 31.985961 -110.567984 3582 S Cienega Creek at Interstate 10
4290 Mescal 31.984859 -110.480878 3980 P 2 miles northwest of Mescal
4295 Doppler 31.893632 -110.630409 5265 WS Doppler Tower in the Empire Mountains
4296 Doppler 31.893632 -110.630409 5265 WD Doppler Tower in the Empire Mountains
4301 Doppler 31.893632 -110.630409 5265 RH Doppler Tower in the Empire Mountains
4302 Doppler 31.893632 -110.630409 5265 T Doppler Tower in the Empire Mountains
4310 Davidson Canyon 31.993577 -110.645169 3480 P Davidson Canyon Wash 0.25 miles south of Interstate 10
4313 Davidson Canyon 31.993577 -110.645169 3480 S Davidson Canyon Wash 0.25 miles south of Interstate 10
4320 Empire Mountain 31.885183 -110.638847 5590 P Empire Peak
4410 Haystack Mountain 31.905498 -110.452810 5052 P Haystack Mountain
6020 SCR Ina Road 32.337252 -111.080133 2173 P Santa Cruz River at Ina Road
6023 SCR Ina Road 32.337252 -111.080133 2173 S Santa Cruz River at Ina Road
6040 SCR Valencia 32.133055 -110.993092 2461 P Santa Cruz River at Valencia Road
6043 SCR Valencia 32.133055 -110.993092 2461 S Santa Cruz River at Valencia Road
6050 SCR Continental 31.855121 -110.978779 2857 P Santa Cruz River at Continental Road
6053 SCR Continental 31.855121 -110.978779 2857 S Santa Cruz River at Continental Road
6060 SCR Conoa 31.745096 -111.037006 3008 P Santa Cruz River at Elephant Head Road
6063 SCR Conoa 31.745096 -111.037006 3008 S Santa Cruz River at Elephant Head Road
6080 Tubac 31.613188 -111.040125 3179 P Santa Cruz River at Tubac
6083 Tubac 31.613188 -111.040125 3179 S Santa Cruz River at Tubac
6110 Avra Valley Air Park 32.429018 -111.225057 1982 P Santa Cruz River 0.5 miles east of Sanders Road
6180 Arroyo Chico at Cherry 32.216285 -110.947760 2427 P Arroyo Chico at Cherry Street
6183 Arroyo Chico at Cherry 32.216285 -110.947760 2427 S Arroyo Chico at Cherry Street
6190 Arroyo Chico at Randolph Way 32.214818 -110.918475 2487 P Arroyo Chico at Randolph Way
6193 Arroyo Chico at Randolph Way 32.214818 -110.918475 2487 S Arroyo Chico at Randolph Way
6200 Summitt View Elementary School 32.066409 -110.942689 2648 P Summit Street at Epperson Lane
6210 Franco Wash at Swan 32.054594 -110.893263 2742 P Franco Wash at Swan Road
6213 Franco Wash at Swan 32.054594 -110.893263 2742 S Franco Wash at Swan Road
6220 Pima County Fairgrounds 32.034347 -110.774890 3082 P Houghton Road at Dawn Road
6230 Ajo Detention Basin 32.183486 -110.926869 2528 P Tucson Diversion Channel at Ajo Detention Basin
6233 Ajo Detention Basin 32.183486 -110.926869 2528 S Tucson Diversion Channel at Ajo Detention Basin
6240 Ajo Way Country Club Road 32.173808 -110.926859 2547 P Country Club Road near Columbia Street
6250 Golf Links at Craycroft 32.192829 -110.875637 2620 P Craycroft Road at Golf Links Road
6260 TEP (Tucson Electric Power) 32.162356 -110.896578 2630 P Irvington Road at Belvedere Avenue
6270 Pima Air Museum 32.141292 -110.864109 2730 P Valencia Road at Pima Air Museum
6280 Wilmot Road 32.044976 -110.856818 2850 P Wilmot Road 2 miles south of Old Vail Connection Road
6286 Corona 31.970612 -110.796090 3143 WD Sahuarita Road at Sewage Treatment Plant
6289 Corona 31.970612 -110.796090 3143 WS Sahuarita Road at Sewage Treatment Plant
6290 Corona 31.970612 -110.796090 3143 P Sahuarita Road at Sewage Treatment Plant
6291 Corona 31.970612 -110.796090 3143 RH Sahuarita Road at Sewage Treatment Plant
6292 Corona 31.970612 -110.796090 3143 T Sahuarita Road at Sewage Treatment Plant
6294 Corona 31.970612 -110.796090 3143 BP Sahuarita Road at Sewage Treatment Plant
6310 Keystone Peak 31.876936 -111.215161 6170 P Keystone Peak
6315 Tinaja Ranch 31.838258 -111.148739 3900 WS near Caterpillar Proving Ground
6316 Tinaja Ranch 31.838258 -111.148739 3900 WD near Caterpillar Proving Ground
6320 Tinaja Ranch 31.838258 -111.148739 3900 P near Caterpillar Proving Ground
6321 Tinaja Ranch 31.838258 -111.148739 3900 RH near Caterpillar Proving Ground
6322 Tinaja Ranch 31.838258 -111.148739 3900 T near Caterpillar Proving Ground
6330 Anamax 31.879093 -111.058166 3450 P Mission Road north of Continental Road
6350 Elephant Head 31.726839 -110.969423 3470 P near Elephant Head Butte
6370 Arivaca 31.604490 -111.341139 3680 P Las Guijas Mountains near Arivaca
6380 Altar Wash at Hwy 286 31.839169 -111.404334 2985 P Altar Wash at Highway 286
6383 Altar Wash at Hwy 286 31.839169 -111.404334 2985 S Altar Wash at Highway 286
6390 Florida Canyon 31.761606 -110.846010 4400 P Florida Canyon Work Center
6410 Diamond Bell 31.989911 -111.298012 3255 P Diamond Bell near Stagecoach Road at Killarney Avenue
6420 Brawley Three Points 32.075621 -111.338278 2552 P Brawley Wash at Highway 86
6423 Brawley Three Points 32.075621 -111.338278 2552 S Brawley Wash at Highway 86
6430 Valahala 32.118864 -111.114478 2540 P Wade Road at Los Reales
6440 Brawley Mile Wide 32.248143 -111.243934 2216 P Brawley Wash at Milewide Road
6443 Brawley Mile Wide 32.248143 -111.243934 2216 S Brawley Wash at Milewide Road
6450 Hilltop @ Riveria Drive 32.043672 -111.241836 2948 P Hilltop Road at Riveria Road
6460 Picture Rocks Comm Center 32.309863 -111.237155 2185 P Picture Rocks Community Center
6470 Michigan at Calgary 32.170073 -111.088317 2564 P Michigan Street at Calgary Avenue

Sensor Key

Precipitation gauge, tipping bucket type, measure in 1mm or 0.03937 inch increments, check-in every 12 hours and each increment during an event reported in inches
Stage (water level), mostly pressure transducer type, check in every 12 hours, usually each 0.2 foot  increment during an event reported in feet
Air temperature, sensor read every 30 minutes reported in degrees Fahrenheit
H   Relative humidity, sensor read every 30 minutes reported in percent
WS Wind speed, average wind speed reported every 3 km of wind run reported in miles per hour 
WD Wind direction, average direction reported every 3 km of wind run reported in degrees azimuth
B Barometric pressure, sensor read every 30 minutes reported in millibars, corrected to sea level