Operations Update

Earlier this year, the state announced State Water Project (SWP) allocations of 10% of contracted supplies for 2024 as winter rain, snow and the hoped-for wet El Niño weather conditions were slow to materialize. The state may increase or decrease the allocation amount as the year proceeds based on hydrological conditions.

State Water Project (SWP) allocations to state water contractors for 2023, such as SGVMWD, were increased to 100% of plan for the first time since 2006, helping stabilize water supplies statewide and in the San Gabriel Valley. Thus, the District was allocated 28,800 acre-feet of imported water in 2023 to deliver and use for replenishment of groundwater in the Main San Gabriel Basin. Some of the District’s allocation for 2023 will be carried over into 2024 as capacity to deliver and store water in the Basin was limited late in 2023 due to high volumes of water in the system.

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 collaboration and smart water management with other water agencies in the Main San Gabriel Basin.

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.

In January, the District delivered 1,934 acre-feet (AF) of water to cyclic storage. Power generation in December 2023 was 225 MWh and 469 MWh in January 2024.  Three important facility maintenance projects remain in progress: the Hydro 24-inch Butterfly Valve Replacement Project; the San Gabriel Flow Control Structure 30-inch Ball Valve Replacement Project and Schedule I Pipeline Continuity Bonding and Corrosion Assessment Validation Project.

As this newsletter was being completed, the San Gabriel Valley and much of California were in the midst of intense “atmospheric river” storm events that are quickly and vastly changing our “water year” data. We began 2024 with improved water supplies compared to January 2023, but the forecasted El Niño conditions were slow to materialize. The graphs above show what a difference a month makes! In fact, since the February graph was completed, rainfall has increased to 71% of average in the Valley and snowpack has increased to 47% of the April 1 average.

It will be interesting to see how the rest of the winter/early spring plays out and how 2024 compares to last year when we experienced the 10th wettest year since recordkeeping began 128 years ago.

One of the most important indicators for the San Gabriel Valley is local groundwater which improves more slowly due to the time it takes stormwater runoff to percolate down to groundwater levels. Our local groundwater levels have risen more than 40 feet since January 2023.

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 February 1, 2024, the level stood at 221 feet above mean sea level, more than 40 feet higher than a year ago.

Prior to heavy precipitation and storms in early 2023, 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. 

Note: 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. 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 2023, 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. Those deliveries have been maximized as much as the delivery and storage “system” can handle, and some of the District’s allocation is being carried over into 2024. 

As presented earlier, the state has forecasted allocations at 10% of requested supplies for 2024. A final allocation plan is usually determined in May or June based on evolving hydrological conditions. 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 – With a wet January and a wet start to February, snowpack has risen to 33% of the April 1 “peak” and is poised to rise higher if current storms continue. 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.

Given above average reservoir levels, current storms and El Niño conditions, California needs to be prepared for both dry and flood conditions in the months ahead. 

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 December 31, 2023, (the latest statewide data available to us), reservoir levels were 117% of average and 65% of capacity. Most reservoirs in the state are above average. As of February 4, storage levels at Shasta Lake, the state’s largest reservoir, were 82% of capacity and 123% of the historical average for this date, and storage levels at Lake Oroville, the state’s second largest reservoir, were 76% of capacity and 130% of the historical average.

Locally, San Gabriel Reservoir was at 33% of capacity and 103% of average, and Cogswell Reservoir was at 9% of capacity and 39% of average. Lake Silverwood, which rests above San Bernardino and is adjacent to the start of the District’s Devil Canyon-Azusa Pipeline, is filled to about 92% of capacity and 109% 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.