Before drainage channels were built to divert water to the sea, the rain that fell on the foothills of the Santa Ana Mountains and slopes of the San Joaquin Hills settled in the lowland creating a vast waterlogged marshy ground.
This lowland, an early Orange County landmark that stretched from Upper Newport Bay almost to Red Hill, was known to Spaniards and Californians as the Cienega de las Ranas (The Swamp of the Frogs). It was covered with willows, tules and guatamote and had long been the dwelling place of millions of tree frogs.
During the winter none of this area could be crossed, even on horseback, but in the spring and summertime, when travelers did cross the swampland on that stretch of the Camino Real, they took their bearings from the frogs' collective high-pitched chorus. On dark nights, travelers were guided by the singing of these frogs and knew they were close to Red Hill, formerly known as the Hill of the Frogs.
The tract sometimes called Cerrito de las Ranas and sometimes Cienega de las Ranas was once part of the three large grants that went into the making of the Irvine Ranch that was known as San Joaquin.
One of the turning points in early California history was the Secularization Act of 1833, under which the Mexican government repossessed and distributed land that the Spanish crown had previously allocated to the California missions.
One of these mission ranchos was the Cerrito or Cienega de las Ranas that later became the property of Don Jose Sepulveda.
On old maps one can find Red Hill by looking for the Cerrito de las Ranas . A spring of water near there was called Aguaje de las Ranas and even the canyon reaching from the Irvine Ranch house almost to County Park was named Canada de las Ranas . That region might well have been dubbed the Kingdom of the Frogs.
Frogs still croak along patches of water on the fringes of Red Hill but their high-pitched singing has long since vanished.
What was once the great frog pond of the cienegas is now covered by the immense buildings of the U. S. Navy's Lighter-than-Air Base.