Operations Update

Following the April 20, 2023, announcement that State Water Project (SWP) allocations to state water contractors, such as SGVMWD, were being increased to 100% of plan for the first time since 2006, the benefits have continued to flow to the Main San Gabriel Basin and our member cities. The increase means the District will be allocated 28,800 acre-feet of imported water in 2023 to deliver and use for replenishment of groundwater in the Main San Gabriel Basin.

We are working closely with state and county water agencies to utilize available capacity in reservoirs, pipelines and spreading grounds to deliver the imported water. With water delivery capacity at times challenged by the abundance of stormwater runoff and snow melt throughout the state, scheduling deliveries is complicated and requires smart water management. Some of the 2023 water deliveries will likely need to carry over into the next calendar year.

In October, the District delivered 1,863 acre-feet (AF) of water to cyclic storage and 858 AF to Covina Irrigating Company on behalf of Three Valleys Municipal Water District. The District’s Devil Canyon-Azusa Pipeline is currently being dewatered in the city of Glendora and construction for the Schedule I Pipeline Continuity Bonding/Corrosion Assessment Validation Project should begin the week of November 20, 2023. On May 15th, the District began generating power at its San Dimas Hydroelectric Facility for the City of Azusa. Power generation in October was 616.2 MWh. 

Imported water supplements local groundwater supplies in the Main San Gabriel Basin and Raymond Basin, the primary sources of water for the District’s member cities of Alhambra, Azusa, Monterey Park, and Sierra Madre. The planned allocation may be adjusted in the future based on hydrological conditions.

Water supply conditions in the state and the San Gabriel Valley remain much improved since last winter’s storms and Hurricane Hilary in the summer. And imported water allocations from the State Water Project are at 100% for the first time since 2006, meaning there is more imported water flowing to our area to help replenish groundwater levels. 

Recently, scientists with NOAA (National Oceanic Atmospheric Administration) indicated global ocean and surface temperatures have surged to record levels in the past few months, strengthening an El Niño condition which may lead to heavy rain in some coastal areas of California. In El Niño years, warmer waters in the eastern Pacific create an active jet stream over the southern U.S. in the winter, leading to higher chances of cool and wet weather in the southwest and warmer and drier weather in the northwest.

The graphics above show the marked improvement from January through November 2023 in state and local reservoir, snowpack and groundwater conditions, including significant lessening of drought conditions statewide. Local groundwater, which improves more slowly due to the time it takes stormwater runoff to percolate down to groundwater levels, has risen more than 50 feet year-to-date!

The Main San Gabriel Basin captured more than 95% of stormwater to supplement local groundwater supplies in the storm surge earlier this year, which is much different than other watersheds that convey the majority of their stormwater to the Pacific Ocean as a flood control measure. Data from Watermaster reveal that of the more than 500,000 acre-feet of stormwater captured this year, about 300,000 AF came from the San Gabriel River watershed.

We must remember we live in a region where most years are dry, we use more water than Mother Nature provides, infrastructure is aging, drought will return, and climate change makes the work of water planning and delivery challenging. We need to sustain our focus on investments in long-term water infrastructure and developing a long-term water conservation ethic. 

Groundwater – in the Main San Gabriel Basin, the “Baldwin Park Key Well” is the indicator of local groundwater levels (see graph below – blue line includes cyclic storage; black line does not). As of November 3, 2023, the level stood at 228 feet above mean sea level.

Prior to the storms earlier this year, the Basin had experienced a steady decline in groundwater levels from a high of 212.5 feet above mean sea level in December 2019 and was trending downward toward the historic low of 169.4 recorded on November 21, 2018. One vertical foot is equivalent to about 8,000 acre-feet of groundwater in the Main Basin. Watermaster’s operating guidelines for replacement water or “safe yield” is between 200 and 250 feet above mean sea level. 

About 80 percent of the Valley’s water supply is furnished by local groundwater, and the Valley imports about 20 percent of the water we use from northern California and the Colorado River. A 60 percent allocation is needed to meet the demand of our member cities for replacement water. Thus, in years where the allocation dips below that amount, we see the important role that water storage and water conservation play.

Note: Groundwater use accounts for 41% of California’s total water supply (80% in the San Gabriel Valley) on an average, annual basis, and as much as 58% in a critically dry year. About 85% of public water systems rely on groundwater as their primary supply. Of water diverted and pumped in California, about 80% is used by agriculture and 20% is used by cities and towns.

Imported Water – In April, the California Department of Water Resources increased State Water Project allocations to State Water Contractors such as SGVMWD for 2023 to 100% for the first time since 2006. Imported water is used to supplement local groundwater supplies in the Main San Gabriel Basin.

Note: Two-thirds of California’s water originates in the Sierra Nevada Mountains and flows through the Delta, a large inland river delta and estuary in northern California.

Statewide Snow Pack – as of November 1, the State is reporting 0% of accumulation for its snow data, effectively starting its recordings anew as we head into the late fall and winter months. Snowpack is measured from April 1 to March 31, a 12-month period. April 1 is usually the “high point” for snow accumulation each year.

Note: On average, the Sierra Nevada Mountains snowpack, which is a key source of water banked in reservoirs, supplies about 30% of California’s water needs as it melts in the spring and early summer, feeding reservoirs and the water table, resulting in groundwater. The snowpack is often referred to as California’s “frozen reservoir.”

Statewide Reservoir Levels – statewide, as of September 30, 2023, (the latest statewide data available to us), reservoir levels had risen to 128% of average and 71% of capacity. As of November 1, storage levels at Shasta Lake, the state’s largest reservoir, were 69% of capacity and 129% of the historical average for this date, and storage levels at Lake Oroville, the state’s second largest reservoir, were 69% of capacity and 134% of the historical average. 

Locally, both San Gabriel Reservoir and Cogswell Reservoir are concluding sediment removal, and Lake Silverwood, which rests above San Bernardino and is adjacent to the start of the District’s Devil Canyon-Azusa Pipeline, is filled to 89% of capacity and 103 of average. 

Note: Every winter, most areas need about 12 inches of rainfall before the ground is saturated enough to get large amounts of runoff into streams and reservoirs. California’s reservoirs generally hold enough water to go one dry year without impacts but begin to empty if a wet year does not follow.