Dry conditions mean smaller flows

Expert explains current water situation for region

Editor’s note: This is the fourth and last in a series covering the Southwest Ag Summit held in Yuma Feb. 20-22.

If you lived here all summer and winter, you might have noticed that it’s been warmer and drier than usual. Dr. Paul Brown, an extension specialist and research scientist with the Soil, Water and Environmental Science Department at the University of Arizona Cooperative Extension, reviewed current water conditions in Arizona during the recent Southwest Ag Summit.

The news was not good. The Salt, Verde, Gila and Colorado river drainages are all “exceptionally dry.” The drainages are also all 4 degrees above normal, which translates into very poor snow yields.

“We haven’t had any rain, and when it rained we didn’t get any snow in the mountains,” Brown said.

The region is currently under La Niña weather conditions, which in the Southwest means a lot of dryness.

“It has been incredibly warm day and night throughout Arizona until a couple days ago,” Brown noted. “It makes for a miserable situation in forecasting.”

The Colorado Basin has been mostly dry except for Wyoming. In January, the major drainage basins in Colorado and Arizona were very dry. Recent winter storms have improved conditions in part of Colorado and northwest and southeast Arizona, but it’s been warm in the entire western U.S., with temperatures 3 to 6 degrees or more above normal.

“So we had a very warm and a very dry winter,” Brown noted.

In addition, the headwaters of regional rivers are in severe drought conditions.

Snow monitoring in the high elevations show almost no snowpack in the western U.S. Snowpack is greatly reduced, with Arizona in general below 50 percent of median. The Gila River snowpack is 9 percent of median, the Salt River 7 percent of median, and the Verde River is 28 percent of median — “way, way below of where it should be historically,”

Brown said.

According to the latest assessments, soil moisture in the Southwest has declined considerably since November due to lack of precipitation.

The spring flow projections for the Colorado Basin rivers are also below normal. Current projections, according to the National Oceanic and Atmospheric Administration Colorado Basin River Forecast Center, show the Colorado will be at 51 percent (56 percent of median), the San Juan at 40 percent (46 percent of median), the Green at 67 percent (76 percent of median), the Gunnison at 54 percent (63 percent of median), the Gila at 23 percent (44 percent of median), the Salt at 19 percent (27 percent of median) and the Verde at 25 percent (49 percent of median).

Brown pointed out that there is good snowpack in the Colorado Rockies, but it’s not coming down the Colorado River. “It hasn’t been good enough,” Brown noted.

The reservoir status in the Upper Basin is mostly at or above normal, but for the Lower Basin, it’s generally below normal. Lake Powell is at 84 percent of the average, Lake Mead is at 57 percent, San Carlos Lake at 17 percent, and Verde Lake at 71 percent. The Salt system is the only reservoir currently above average at 104 percent.

In spite of being below normal, Brown said the Colorado River and other river shortages are not in the historic low level yet.

He pointed out that most years, water inputs to Lake Mead are less than the downstream usage, which results in a loss of 5 to 12 feet in elevation each year. The good news is that projections indicate there won’t be a shortage in 2018. The 2019 projection still indicates above-shortage levels.

However, the projection for 2020 is “looking less optimistic,” Brown said, adding that Arizona will “need wet winters” to avoid drastic shortages in the future.

Perri Benemelis, manager of the Central Arizona Groundwater Replenishment District, and Andrew Caddock, CAGRD analyst, explained the pilot fallowing program designed to conserve water.

CAGRD is currently working with the Yuma Mesa Irrigation and Drainage District in the program. Under the agreement, volunteer farmers are paid not to grow crops and, thus, the district does not divert Colorado River water that otherwise would be used to irrigate the lands.

About 1,500 fallowed acres, which is about 10 percent of the irrigated acres in the district, are currently part of the program. To qualify, the lands must have produced crops in four of the last five years. The program required at least five contiguous acres that would be irrigated if not enrolled in the program.

The base price is $750 an acre. The YMIDD reimbursement is $21.36 an acre, with the district receiving $10,000 a year for administering the program.

Benefits to the YMIDD, according to CAGRD, include providing a stable revenue stream for district farmers with limited impact on current farming operations; avoiding permanent loss of productive agricultural land and minimizing any adverse local economic impact; enhancing existing rotational farming practices; and serving an agronomic benefit by allowing a longer rest-rotation for some lands.

Benefits to the CAGRD include allowing the organization to develop data, methodologies and processes to inform a future longerterm high priority water supply fallowing program; developing relationships with on-river entitlement holders that could lead to a longer-term water supply for the CAGRD; and the conservation of water supply retained in Lake Mead, helping to avoid shortages to water users in Arizona and the Lower Basin.

CAGRD also worked with the Bard Water District in the fallowing pilot program. The project was for two years, 2016 and 2017, and capped at 2,000 acres, which were fallowed from April 1 through July 31.

The Metropolitan Water District of Southern California paid $400 per participating acre per year. The project conserved two acrefeet of water for every acre fallowed.