La Mesa Reservoir, the original name, was formed in 1894 behind an earthen dam on the boundary between what would become La Mesa and San Diego. Earthen dams are older than recorded history, functional and vulnerable in roughly equal measure: they work well in normal conditions and fail catastrophically in extreme ones. The 1916 floods tested the dam severely. The dam survived, and the reservoir — newly central to the city's water supply after the flooding reorganized which infrastructure was doing how much work — was enlarged in 1919. The following year it was renamed Lake Murray, honoring James Andrew Murray, the Montanan who held majority ownership in the water company that had developed the reservoir.

Charles Hatfield called himself a moisture accelerator rather than a rainmaker, a distinction that mattered to him professionally even if it struck observers as semantic. His method involved proprietary chemicals evaporated from towers, a trade secret he never fully disclosed. Whether the floods of January 1916 had anything to do with his chemicals or were simply exceptional weather that arrived on schedule is a question that cannot be answered definitively. San Diego received nearly 30 inches of rain in a matter of weeks. The city council refused to pay, arguing that no human agent could be credited with what was clearly a natural disaster. Hatfield's lawsuit eventually expired without resolution. He continued practicing his trade elsewhere.

Lake Murray covers 171.1 acres at its full pool, with a maximum depth of 95 feet and a shoreline of 3.2 miles. It sits in a valley south of Cowles Mountain and east of the 8 Freeway, embedded in residential San Diego in a way that gives it a dual character: municipal water infrastructure that also functions as a community park. Kayaking and fishing are popular; the lake supports a healthy population of bass, catfish, and trout. At least 149 bird species have been recorded at the lake, including the tricolored blackbird, listed as a species of special concern in California. The surrounding parkland provides a slice of open space in a heavily developed part of the city.

Pilots approaching Montgomery-Gibbs Executive Airport (KMYF) use Lake Murray as an aeronautical reporting point — the lake appears on approach charts as a visual checkpoint, its distinctive shape recognizable from the air even on days when the urban grid below makes individual landmarks hard to distinguish. This function — a reservoir serving as aviation infrastructure — is a reminder that landscape features in cities carry multiple simultaneous purposes that designers never planned. The engineers who built the earthen dam in 1894 were solving a water storage problem. The pilots who use the lake as a waypoint are solving a navigation problem. The two uses overlap in space without awareness of each other, which is how urban geography usually works.