Water Woes XVIII-Colorado River & Drought Status
Colorado River Status
The Colorado River situation continues to degrade. In the wake of the Tortolita Alliance (TA) letter to the United States Bureau of Reclamation (USBR) recommending a 20% permanent cut of Colorado River deliveries, the Director of the Arizona Department of Water Resources (ADWR) also sent a letter to USBR citing the "dire situation" and recommending 13 action actions including "progressive and aggressive federal leadership". You can download these letters at the links below.
Current Reservoir Conditions
As of 9/12/22, Lake Powell was 24% full and Lake Mead was 28% full which is significantly lower than September 2021.
Tier 2a Shortage Declared For 2023
The USBR has declared a Tier 2a Shortage for 2023 which will require Arizona to cut 592,000 acre-feet (af), which is 21% of its 2.8 million acre-feet (maf) allotment (see chart above).
The USBR did not impose the 2-4 maf cut suggested by USBR Commissioner Touton in June-see Water Woes XVII-Disaster Looming. This has disappointed many because California does not have to make any cuts in 2023 under Tier 2a (see chart above).
Impact On Central Arizona Project (CAP)
Remember from TA's Know Your H2O Part VIII-CAP that the CAP receives 1.52 maf of Colorado River water from Arizona's 2.8 maf allotment. The above graphic shows how the 2023 Tier 3 shortage will impact the CAP. Only 3% of municipal/industrial contractors will be cut and these are primarily in the Phoenix region. If conditions worsen, future Tier Shortages will adversely impact municipal/industrial water agencies throughout Arizona.
TA attended the Local Drought Impact Group (LDIG) Meeting via Microsoft Teams on 9/14/22.
LDIG is a bi-monthly gathering of local and state water agencies to discuss latest drought conditions across the state of AZ. Attendees include: TA, Marana Water, Tucson Water, Metro Water, National Weather Service-Tucson, Central Arizona Project (CAP), Arizona Department of Water Resources (ADWR), Pima County Office of Sustainability & Conservation (OSC) and more. The following information was gleaned from the meeting.
Arizona Drought Improves
The monsoon rains this summer have improved drought conditions in Arizona. In June, 62% of Arizona was rated as Severe Drought and now it is 23.5%.
This is good news for AZ rivers, stream and aquifers, but remember this is a short short snapshot and 36% of Arizona water supply comes from the Colorado River.
Average Monsoon Season
The monsoon season extends from June 15 to September 30. The black line on the graph above is the average historic monsoon rainfall. Through August 25, the total 2022 monsoon precipitation was normal with 4.13" measured at the Tucson Airport.
The Water Year extends from October 1 through September 30. Total 2021/22 Water Year precipitation at the Tucson Airport through August is 6.25" compared to normal precipitation of 9.29".
Note that precipitation in other areas of Pima County can be higher or lower than the official readings at Tucson Airport because monsoonal rain is very variable depending on location.
Future Weather Predictions
The weather forecasters are predicting continued La Niña conditions (dry) for the remainder of 2022 and a 50% chance of La Niña conditions this coming winter.
The national drought outlook map shows continued drought in a large portion of the Colorado River watershed and continued improvement in Arizona.