Lower Colorado Region HUC 15
The Lower Colorado Region hydrologic region spans Arizona, California, Nevada, New Mexico, Utah and is divided into 85 HUC8 sub-basins. Conditions are the US Drought Monitor's weekly area coverage and the day-of-year streamflow percentiles of the USGS gauges inside each sub-basin, as of 2026-09-07.
Health score
62
Moderate
Drought index
201
Severe
Area in D2+
31.8%
27 sub-basins ≥50%
Gauges below normal
59%
of 232 reporting
Water assets
134,833
avg WIS 50.5
Sub-basins
85
3,037 alerts · 22 transfers
quality 50drought 60streamflow 51regulatory 98coverage 70
Sub-basins, driest first
| Sub-basin | Assets | Avg WIS | Drought | Gauges low | Flow pct | Health |
|---|---|---|---|---|---|---|
| Lower Gila-Painted Rock Reservoir 15070101 · AZ | 2,262 | 47.8 | Extreme (300) | 50% | p43 | 49 |
| Lower Virgin 15010010 · AZ, NV, UT | 1,401 | 57.6 | Extreme (300) | 0% | p71 | 63 |
| Fort Pearce Wash 15010009 · AZ, UT | 775 | 53.3 | Extreme (300) | 100% | p10 | 43 |
| San Francisco 15040004 · AZ, NM | 4,568 | 56.7 | Severe (297) | 100% | p7 | 34 |
| Upper Virgin 15010008 · UT | 3,152 | 53.9 | Severe (296) | 17% | p56 | 59 |
| Upper Puerco 15020006 · AZ, NM | 1,601 | 55.5 | Severe (296) | — | — | 48 |
| Santa Rosa Wash 15050306 · AZ | 635 | 52.9 | Severe (296) | — | — | 47 |
| Lower Colorado-Marble Canyon 15010001 · AZ | 942 | 58.9 | Severe (295) | 100% | p17 | 40 |
| Moenkopi Wash 15020018 · AZ | 334 | 51 | Severe (295) | 100% | p10 | 43 |
| Rio Sonoyta 15080102 · AZ, MX | 105 | 50.6 | Severe (294) | 100% | p10 | 43 |
| Black 15060101 · AZ | 1,284 | 61.8 | Severe (291) | 100% | p15 | 42 |
| Corn-Oraibi 15020012 · AZ | 79 | 47.8 | Severe (289) | — | — | 45 |
| Tenmile Wash 15070202 · AZ | 347 | 57.5 | Severe (288) | — | — | 50 |
| Polacca Wash 15020013 · AZ | 374 | 58.4 | Severe (285) | — | — | 51 |
| Grand Wash 15010006 · AZ, NV | 349 | 57.6 | Severe (279) | — | — | 51 |
| Kanab 15010003 · AZ, UT | 1,131 | 54.1 | Severe (276) | 50% | p46 | 53 |
| Animas Valley 15040003 · AZ, NM | 1,001 | 50.4 | Severe (269) | — | — | 48 |
| Upper Gila-Mangas 15040002 · AZ, NM | 1,647 | 53.4 | Severe (267) | 100% | p7 | 38 |
| Upper Gila 15040001 · NM | 1,361 | 58.6 | Severe (265) | 100% | p6 | 37 |
| Meadow Valley Wash 15010013 · NV, UT | 873 | 55.9 | Severe (263) | 0% | p64 | 64 |
| Grand Canyon 15010002 · AZ | 1,190 | 58.1 | Severe (260) | 25% | p45 | 59 |
| Leroux Wash 15020009 · AZ | 221 | 60.6 | Severe (260) | — | — | 54 |
| Lower Santa Cruz 15050303 · AZ | 3,134 | 43.2 | Severe (258) | 50% | p47 | 50 |
| Cottonwood Wash 15020011 · AZ | 612 | 58.2 | Severe (258) | — | — | 53 |
| Dinnebito Wash 15020017 · AZ | 68 | 47.2 | Severe (258) | — | — | 48 |
| San Cristobal Wash 15070203 · AZ | 347 | 55.4 | Severe (250) | — | — | 53 |
| White 15010011 · NV | 826 | 54.5 | Severe (248) | 0% | p51 | 67 |
| Centennial Wash 15070104 · AZ | 1,648 | 45.6 | Severe (247) | 100% | p10 | 44 |
| San Carlos 15040007 · AZ | 1,113 | 57.4 | Severe (247) | 100% | p10 | 48 |
| Lower Puerco 15020007 · AZ | 469 | 52.8 | Severe (243) | — | — | 52 |
| San Simon Wash 15080101 · AZ, MX | 720 | 55.3 | Severe (240) | — | — | 54 |
| White 15060102 · AZ | 397 | 59.2 | Severe (240) | 50% | p40 | 59 |
| Jadito Wash 15020014 · AZ | 218 | 54.8 | Severe (240) | — | — | 53 |
| Little Colorado Headwaters 15020001 · AZ, NM | 1,011 | 55.1 | Severe (227) | 50% | p41 | 51 |
| Tule Desert 15080103 · AZ, MX | 34 | 50.6 | Severe (227) | — | — | 53 |
| Hassayampa 15070103 · AZ | 1,844 | 51.6 | Severe (226) | 100% | p5 | 42 |
| Aguirre Valley 15050305 · AZ | 284 | 55 | Severe (226) | — | — | 55 |
| Carrizo 15060104 · AZ | 477 | 60.7 | Severe (223) | 0% | p40 | 71 |
| Lower Salt 15060106 · AZ | 2,328 | 46.8 | Severe (218) | 100% | p10 | 47 |
| Havasu Canyon 15010004 · AZ | 1,280 | 55.4 | Severe (218) | 100% | p10 | 50 |
| Upper Gila-San Carlos Reservoir 15040005 · AZ | 4,806 | 51.2 | Severe (215) | 20% | p45 | 61 |
| Lower Gila 15070201 · AZ | 2,226 | 47 | Severe (215) | 63% | p10 | 50 |
| Lake Mead 15010005 · AZ, NV | 1,369 | 55.5 | Severe (215) | 100% | p9 | 39 |
| Middle Gila 15050100 · AZ | 4,478 | 46.3 | Severe (211) | 100% | p5 | 39 |
| Zuni 15020004 · AZ, NM | 1,182 | 55.8 | Severe (208) | 100% | p15 | 50 |
| Cloverdale 15080303 · MX, NM | 76 | 52.1 | Severe (208) | — | — | 55 |
| Carrizo Wash 15020003 · AZ, NM | 912 | 55.8 | Severe (207) | — | — | 57 |
| Muddy 15010012 · NV | 528 | 52.6 | Severe (206) | 57% | p10 | 53 |
| Imperial Reservoir 15030104 · AZ, CA | 5,931 | 46.4 | Severe (200) | 60% | p12 | 50 |
| Havasu-Mohave Lakes 15030101 · AZ, CA, NV | 5,129 | 45.8 | Severe (200) | — | — | 53 |
| Yuma Desert 15030108 · AZ, MX | 4,256 | 42.3 | Severe (200) | 100% | p13 | 44 |
| Las Vegas Wash 15010015 · NV | 2,230 | 44.6 | Severe (200) | 19% | p69 | 60 |
| Lower Colorado 15030107 · AZ, CA, MX | 1,885 | 44.8 | Severe (200) | 61% | p13 | 51 |
| Silver 15020005 · AZ | 1,459 | 52.4 | Severe (200) | 100% | p4 | 39 |
| Upper Little Colorado 15020002 · AZ, NM | 1,230 | 50.9 | Severe (200) | 75% | p10 | 49 |
| Sacramento Wash 15030103 · AZ | 1,015 | 49.9 | Severe (200) | — | — | 55 |
| Bouse Wash 15030105 · AZ | 859 | 47.2 | Severe (200) | — | — | 54 |
| Red Lake 15010007 · AZ | 739 | 46.4 | Severe (200) | — | — | 53 |
| Bill Williams 15030204 · AZ | 531 | 55.4 | Severe (200) | 100% | p13 | 51 |
| Piute Wash 15030102 · CA, NV | 312 | 53.8 | Severe (200) | 100% | p10 | 50 |
| Detrital Wash 15010014 · AZ | 279 | 51 | Severe (200) | — | — | 55 |
| Tyson Wash 15030106 · AZ | 205 | 42.4 | Severe (200) | — | — | 51 |
| Lower Verde 15060203 · AZ | 3,486 | 54.1 | Moderate (197) | 50% | p25 | 59 |
| Agua Fria 15070102 · AZ | 6,295 | 48.4 | Moderate (195) | 60% | p10 | 57 |
| Lower Little Colorado 15020016 · AZ | 815 | 53.6 | Moderate (190) | 0% | p61 | 70 |
| Upper Salt 15060103 · AZ | 2,841 | 57.9 | Moderate (189) | 63% | p16 | 56 |
| Tonto 15060105 · AZ | 2,168 | 57.2 | Moderate (173) | 100% | p10 | 53 |
| Big Sandy 15030201 · AZ | 1,287 | 53.3 | Moderate (160) | 100% | p0 | 42 |
| Santa Maria 15030203 · AZ | 1,273 | 54.5 | Moderate (142) | 100% | p10 | 55 |
| Middle Little Colorado 15020008 · AZ | 1,291 | 51.7 | Moderate (126) | 50% | p30 | 65 |
| Upper Verde 15060202 · AZ | 4,894 | 48.3 | Moderate (124) | 50% | p31 | 60 |
| Brawley Wash 15050304 · AZ | 2,532 | 51.4 | Moderate (121) | 100% | p10 | 55 |
| Big Chino-Williamson Valley 15060201 · AZ | 1,576 | 52 | Moderate (117) | 100% | p10 | 56 |
| Burro 15030202 · AZ | 557 | 58.2 | Moderate (114) | 100% | p10 | 58 |
| Chevelon Canyon 15020010 · AZ | 652 | 58 | Moderate (106) | 50% | p51 | 62 |
| Canyon Diablo 15020015 · AZ | 957 | 47.4 | Moderate (102) | 100% | p10 | 55 |
| Rio De La Concepcion 15080200 · AZ, MX | 177 | 49.1 | Moderate (100) | — | — | 65 |
| Lower San Pedro 15050203 · AZ | 2,626 | 53.2 | Abnormally dry (89) | 100% | p9 | 53 |
| San Simon 15040006 · AZ, NM | 2,215 | 47.9 | Abnormally dry (89) | — | — | 65 |
| Upper Santa Cruz 15050301 · AZ, MX | 4,654 | 47 | Abnormally dry (50) | 63% | p10 | 66 |
| Willcox Playa 15050201 · AZ | 2,967 | 45.9 | Abnormally dry (24) | — | — | 71 |
| Rillito 15050302 · AZ | 2,059 | 47.8 | Abnormally dry (23) | 80% | p10 | 62 |
| San Bernardino Valley 15080302 · AZ, MX, NM | 286 | 50 | Abnormally dry (11) | — | — | 74 |
| Upper San Pedro 15050202 · AZ, MX | 3,097 | 47.7 | None (0) | 67% | p10 | 63 |
| Whitewater Draw 15080301 · AZ, MX | 2,049 | 43.9 | None (0) | 50% | p18 | 71 |
Top water assets in this region
- 80Coconino Sandstone Fossil Aquifer — Flagstaff RegionCanyon Diablo
- 76Virgin River And Quail Creek — MopUpper Virgin
- 76Las Vegas Valley Deep Fossil AquiferLas Vegas Wash
- 76Black Mesa N-Aquifer Fossil Water — Navajo NationMoenkopi Wash
- 74Coconino Aquifer — Verde ValleyUpper Verde
- 74Underground Water Wells (2) — MUpper Virgin
- 74Virgin River — IUpper Virgin
- 73Underground Water Well — DisUpper Virgin
- 72Tucson Basin Deep Fossil AquiferUpper Santa Cruz
- 71Sand Hollow Creek — MUpper Virgin