The Colorado River Basin is managed in a complex and multi-level legal structure that involves many stakeholders. The Colorado River watershed is divided into the Upper and Lower Basins. The Upper Basin includes the states of Wyoming, Colorado, Utah and New Mexico. The Lower Basin includes Arizona, California and Nevada. A binational treaty governs the releases to Mexico from the Colorado River.
Within the overall structure of the Law of the River, the basin states and the Boulder Canyon Project Act water contractors must work collectively to address their water supply issues. In the Lower Basin, water supplies are administered by a federal water master, designated by the Secretary of the Interior working through the Bureau of Reclamation. In the Upper Basin, the Upper Colorado River Commission serves in the role of administering compliance with the 1922 Colorado River Compact. In addition, every basin also has its own unique set of law governing rights that apply within those states.
The 2007 Interim Guidelines for Lower Basin Shortages and the Coordinated Operations for both Lake Powell and Lake Mead are set to expire in 2026. The seven Colorado River Basin states and stakeholders must work together to develop the new criteria that will replace those guidelines. At present, there is a gridlock in those negotiations between the Upper and Lower Basin states and it must be resolved in 2025 to replace those guidelines expiring in 2026.
As part of the 2025 SW Ag Summit program on Thursday, 20 February on the campus of Arizona Western College, two sessions will be held addressing the future of the Colorado River and management plans for water allocations that will be very important for agriculture in the lower Colorado River Valley in the next decade. This will include a keynote session in the morning and a breakout session will follow. The schedule for these two sessions is listed below.
Keynote Program, 7:30 a.m., 20 February 2025, College Community Center (3C)
The Future of the Colorado River
Breakout Session – Colorado River Update, 9:30 a.m. MAC 106
Outlook on Basin wide Negotiations for the 2026 Operational Guidelines
PBS News recently did a story on the importance of Yuma’s winter vegetable production and the pressures the Western US is facing due to water scarcity. The story features insights from local growers Matt McGuire, JV Smith Companies and Jon Dinsmore, Dinsmore Farms, as well as Arizona Department of Agriculture Director, Paul Brierley. The report is well done, covering the basics of Yuma agriculture and the water shortage issues the industry is facing. It’s a quality piece, worth a listen.
Check it out by clicking here or on the image below.
Fig. 1. PBS NewsHour: “Arizona Farmers Forced to Adapt as Main Water Source Dries Up” story. (Photo Credits: PBS News)
Calvin’s lab conducted an experiment this fall to evaluate bioinsecticides that can help to control pale striped flea beetles inorganic crops. The experiment was conducted at the Yuma Agricultural Center experimental farm. Four insecticides and insecticide mixes, including Biolink (insect& bird repellent), Biolink + Pyganic, Pyganic, and M-Pede + Entrust, were evaluated along with a nontreated check. Insecticide treatments were applied using chemigation through sprinklers during the last 40 minutes of germination water. Each treatment was applied to a strip of 10 beds of cabbage, and each strip was divided into 4 subsections representing 4 replications. Precautions were taken to avoid cross-contamination across treatments. Because there was a stand issue, stand count data was not considered for evaluation. The treatments were compared using the percentage of damaged plant data. This data was collected by inspecting 20 plants per subsection. We also inspected each of these 20 plants and their immediate surroundings for the presence of flea beetle adults. While we observed a lot of flea beetle damage, we only saw one flea beetle throughout the experiment. The assessment was made on the 4thand the 7th day after application (DAA).
At 4 DAA, all insecticide-treated strips showed a comparable reduction in injured plants. However, only Biolink, Biolink +Pyganic, and M-Pede + Entrust exhibited a level of injured plants that was significantly lower than that of the non-treated control. At 7 DAA, only Biolink showed injured plant incidence that was significantly lower than that of the non-treated control. However, Biolink + Pyganic, and M-Pede + Entrust were comparable to the Biolink alone treatment (Figure 1). The data suggests that the evaluated bioinsecticides and bioinsecticide mixes can be used alternatively when targeting pale striped flea beetles in brassica seedlings. However, an additional application after 4 DAA would be necessary for better protection of the crop.
Figure 1a. Brassica plant with flea beetle feeding injury
Figure 1b. Adult pale striped flea beetle.
Figure 2. Means percentage of cabbage plants damaged by flea beetles. Bars
with the same capital letter or lowercase letter are not statistically different. IBR
= Biolink (insect & bird repellent).
Lake Mead, the nation’s largest reservoir, continues to decline to historic lows, posing a critical hydrological challenge in the Southwest with significant implications for Arizona agriculture. Prolonged and severe drought across the Colorado River Basin has led to cascading water-use reductions, including a Tier 1 shortage that has cut central Arizona’s agricultural water allocations by 65%.
The drought situation in Arizona has intensified significantly since late 2024 (see Figures 1 & 2 to determine the differences in extreme drought expansion), with extreme drought (D3) conditions spreading across much of the state. Yuma, La Paz, Maricopa, Gila, and now Greenlee counties are fully engulfed in D3 drought, while the expansion has also reached parts of Pima, Mohave, Yavapai, Navajo, Apache, Santa Cruz, Graham, and Cochise counties. This alarming trend signals a severe water deficit, raising serious concerns about its impact on agriculture, water resources, ecosystems, and communities statewide. This crisis underscores the urgent need for innovative strategies to sustain agriculture and secure water resources in the region.
One approach to addressing this crisis is implementing conservative water management, which includes adopting advanced soil moisture monitoring technologies. This raises an important question: How do you select the right soil moisture sensors for irrigation management decisions?
A wide range of soil moisture sensors are commercially available for agricultural use. However, selecting the most suitable sensor for Yuma’s arid environment, where soils are characterized by a pH greater than 8 requires careful consideration of key criteria. The selection process should focus on two critical aspects:
(a) Operational Feasibility:
(b) Performance Accuracy:
Calibration: Consideration of factory calibrations versus site-specific calibrations for improved measurement precision.
