Lake Hodges water levels dry up prospects for grebes

For years, pairs of grebes would zoom across the water at Lake Hodges in a dazzling mating dance, and then build their nests on mats of dried brush suspended above the waterline.

This year, some of the birds are still pairing up, but their nesting area near Interstate 15 no longer floods with seasonal rains, and can’t sustain them. The eastern finger of the lake, which long alternated between riparian woodland and seasonal ponds, is permanently drained because of state-ordered changes to the water level.

Anyone who has driven that stretch of freeway south of Escondido, or walked the pedestrian bridge over the lake, has likely seen a flooded forest, where tree branches poke up from glassy water. That offered ideal habitat for grebes, which are powerful swimmers but poor fliers, and would build nests just above the waterline in order to access them. If the water level drops too far below the nest, the parents have trouble reaching it, and the clutch may fail.

In 2019, the California Division of Safety of Dams determined that the water level at Hodges Reservoir should not exceed 295 feet, or 20 feet below the spillway, said Arian Collins, a public information officer for the City of San Diego, which manages the water system through its Public Utilities Department. That mandate requires water officials to release flows from the reservoir when runoff from the 248-square-mile watershed raises its water level. On Wednesday, the lake was just shy of that limit at 292.30 feet after Monday’s storm dropped 0.98 of an inch of rain, he said.

The water level limit is designed to ensure the safety and integrity of the dam, but it also affects surrounding habitat and wildlife. Nature photographer Brian Caldwell has watched with concern as colonies of grebes have suffered nest failures when water levels drop in the eastern portion of the lake.

“In the past, when the lake would fluctuate up and down, the grebes would nest on the east end of the lake, close to the freeway near Rancho Bernardo,” he said. “When water levels would come up, they would nest in floating platforms on dead brush. Now that the water no longer comes that high, the grebes tend not to nest in that area at all anymore. Last year there were a handful of nests. Three or four years ago, I counted 160 pairs of chicks.”

On a recent morning, Caldwell walked the pedestrian bridge above the eastern portion of Lake Hodges, parallel to the freeway. The bottom was matted with brush and studded with snags of dead trees. Although the area has previously been inundated with seasonal rains, this week the only water visible was scattered puddles in the lake bed.

“Three years ago, I would have my boat out in the water there,” he said, pointing out at the marshy ground. “Three to four yeas ago, I was able to get under the freeway.”

Caldwell, a photographer and musician, also runs a service guiding other photographers and visitors around the lake to view and take pictures of wildlife. One of the most spectacular and sought-after displays is the courtship ritual of grebes. Breeding pairs of Western grebes stretch upright and run across the water surface together, propelled by their paddle-like feet.

Birdwatchers visiting Lake Hodges now may get to see the elaborate courting ritual of the Western grebe; it’s known as “rushing.”

(Ernie Cowan)

The City of San Diego, with other agencies including the San Diego County Water Authority, controls water levels at Lake Hodges through its pumping station, managing them for water storage, and drawing down levels in advance of wet weather, Collins said.

In the past, some of the water level changes left grebe nests stranded far above the water line, leading to clutch failures, Caldwell said. He and other environmental advocates complained to the city, asking it to maintain consistent water levels during nesting season. Now, he acknowledged, that choice is outside the discretion of local agencies, which must comply with the state-ordered safety limits.

More than a century old, Hodges Reservoir was created in 1918 when the dam was built on San Dieguito Creek. Its primary purpose is to store and distribute drinking water for the San Dieguito Water District, Santa Fe Irrigation District, and the City of San Diego. So the habitat that grebes use was created with the reservoir, and fluctuates through its management, Collins said.

“It’s important to recognize that the only reason Hodges exists is as an impounding reservoir that is part of the city’s municipal water-supply system,” he said. “With or without the state’s restriction, the water level at Hodges rises and falls based on rains, droughts, and our need to pull water for our drinking water supply. Any changes may affect nesting habits.”

He noted that the two species found at the reservoir — Western and Clark’s grebes — are not listed as threatened or endangered. City biologists monitor the grebes in the spring before mating rituals and nest building, he said.

“Both grebe species are in fact common water birds, with populations ranging from southern Canada to central Mexico,” Collins said. “Other city reservoirs have successful breeding grebe populations as well.”

Caldwell countered that some species that were previously numerous have become endangered or extinct because of habitat loss, and cautioned that people should protect wildlife populations, even for species that currently appear healthy. Although he acknowledged that safety rules take priority for water management at Lake Hodges, he’s saddened by the prospects for the water birds there.

“Currently, grebes probably won’t nest here for the foreseeable future, and that’s a shame, because they’re beautiful birds,” he said.

— Deborah Sullivan-Brennan is a reporter for The San Diego Union-Tribune