The state agency overseeing dams has instructed San Bernardino County to lower the level of Lake Gregory by at least two feet by the end of the year.
That call comes in conjunction with efforts to retrofit the 78-year-old dam that created Lake Gregory. That repair will begin during the upcoming summer.
The California Department of Water Resources Division of Dam Safety has told the county it will need to lower the level of water behind the dam that composes Lake Gregory by two to three feet and should do so by January 1.
The Division of Dam Safety has been studying the situation at Lake Gregory for years. Simultaneously, San Bernardino County has been examining its options in ensuring the seismic stability of the dam.
Located proximate to Crestline in the San Bernardino National Forest, Lake Gregory is an artificial lake created by a Works Progress Administration program which began in 1937. The intent of that project was to dam the east and west forks of Houston Creek, which are San Bernardino Mountain-based natural tributaries of the Mojave River, which flows out into the Mojave Desert. The concept was to keep a portion of the water originating in the mountains in place.
Though they are considered splendid creations, the dam and lake have faced several challenges over the years. Even before it was entirely finished, the dam performed well during an unanticipated test that came about with the deluge of 1938. By the best of calculations, it would normally take nearly three years to fill the lake. It rained so intensely in March 1938 that water was at the brim of the dam in less than four days. It is believed that some of the equipment used in constructing the dam was not evacuated and now resides at the bottom of Lake Gregory.
When the springtime rains of 1938 abated, the dam was not entirely completed and the next challenge was a financial one, as federal funds dried up.
At that point, Arthur Gregory, Sr. swooped in to salvage the project, which was built at a locale then known as Houston Flat. Arthur Gregory, Sr. was a Redlands citrus grower who had purchased and developed land in a nearby area known today as Valley of the Moon. He erected a sawmill at Valley of the Moon to cut wood for crating his “Orange Blossom” brand of citrus fruit. Gregory was a prime mover in creating the Crest Forest County Water District servicing that area. In the spring of 1938, the federal government’s contribution of $160,000 toward the dam project was tapped out. Gregory arranged for the Crest Forest County Water District, with a boost from the infusion of some of his own capital, to cover the remaining $65,000 cost of completing the dam.
A causeway, Lake Drive, was built over the dam in January 1939 as the finishing touch on the project.
In 1992, Big Bear experienced a magnitude 6.5 earthquake, and that shock reverberated across the mountain to Crestline. There was concern that this might have done damage to Lake Gregory, but there is nothing to indicate the dam sustained any structural harm as a result of that seismic event.
Still the same, given the volume of Lake Gregory and the consideration that inadequate compaction of the dirt that composes the dam was undertaken during its construction phase, the dam is given a “high hazard” rating.
Moving toward 80 years after its creation, the $225,000 original construction cost of the dam seems minuscule. Simply shoring up the dam at this point will cost the county $8 million.
It is now deemed wise to lower the lake level to reduce the stress on the earthen dam. Previously, it had been suggested that the level would need to be reduced by at least ten feet and as much as 20 feet to assure the dam’s integrity. An engineering survey indicates letting as little as two to three feet of water out of the lake will reduce the weight load the dam must constantly bear to a point that it will not fail. That reduction will come in addition to a water level drop of several feet that has taken place over the last three years as a result of the drought.
Achieving the drainage recommended by the state presented a challenge, as the valves on the drains from the dam were found to be corroded and locked tight. They had to be replaced. Those drains will vector the water northward so gravity can plunge it down the north face of the San Bernardino Mountains into Lake Silverwood.
After the Lake Gregory seismic retrofit is completed in January 2019, the amount of water held in the dam, and therefore the level of Lake Gregory, can be increased.
Today, the Lake hosts Lake Gregory Recreational Park, which boasts water slides at the west end of the lake. The south shore of the lake is a popular fishing destination. A private beach on the southeast shore features a Tyrolean-styled clubhouse that was part of the San Moritz Lodge, once known as Club San Moritz. The original structure, a grand one, was built in the Valley of the Moon in 1926 along the shore of now-drained Moon Lake.