The L.A. River’s ‘Natural’ History : Until 1825, the Los Angeles Basin was vastly different from the current desert. What was the area’s environment in the distant past?

In light of proposals to restore the concrete-lined Los Angeles River to its “natural” state, plus the recent discovery of fossil bones of an imperial mammoth and a saber-toothed cat beneath Hollywood Boulevard, it’s instructive to reflect on the Los Angeles Basin’s distant past.

How many other such fossils lie below us? What was Los Angeles’ environment really like “way back when”? How many topomorphic revolutions have been wrought here by flood and earthquake since behemoths chewed cud at the Bowl?

Our ideas of the past are likely to be influenced by the city’s chaparral-covered backdrop. It’s easy to assume that the basin of yesteryear was all dust and desolation.

But the lowlands of the coastal plain were vastly different from what we might think. Evidently they were a veritable Garden of Eden during the millennia following the last Ice Age, right down till 1825. The earliest human inhabitants of the lowlands of the South Coast Basin lived in a verdant complex of marsh and forest, not a desert. The L.A. River did not run into the ocean; it dispersed into an extensive wetland matrix.

All that changed overnight in the biggest flood in recorded L.A. history.

For eons, a constant supply of surface and ground-water sustained a superlative matrix of forest and tule in the bottom land of Los Angeles and Orange counties. Large areas of giant sycamore, ash, cottonwood and alder were interspersed with marshes filled with sedges and bull rushes. The coastal edge of the plain was mottled by a string of ancient peat bogs.

Waters of the Los Angeles, San Gabriel and Santa Ana rivers dispersed laterally over the plain. The wintertime runoff leaked through to the Pacific at numerous points. Memoirs and histories by John Warner, Benhamin Hayes, Joseph Widney and Thomas Talbert make it clear that none of the rivers flowed into the ocean until the spring of 1825.

A decade earlier a 10-day deluge had sent the Los Angeles River bursting out of the San Fernando watershed carrying an immense number of fallen trees from higher points. As the waters spread out below Elysian Narrows, the interlock of drifting branches and forest trunks stopped the boulders rocks and gravel flowing with the current. A broad, oval-shaped berm 10 to 15 feet high built up, extending about two-thirds of a mile east from the present-day rail yard below Chinatown to where the Golden State Freeway crosses Main Street.

The river immediately shifted toward the southwest. The large Gabrielino village called Yang-na lying in its new path was turned to a morass of floating wickiups. Bypassing the coastal plain, the river flowed toward the southwest into the present Exposition Park area, then west into the forests and marshes of the Ballona Creek drainage.

Then, in 1825, a hard rainstorm occurred one spring day at the Los Angeles pueblo and broke up in the afternoon. The weather the following day was clear, and a full moon illuminated the landscape that night. The river had risen but had not given cause for alarm.

At midnight an immense wall of water poured through the narrows under the moonlight and broke through the 10-year-old debris dam. The resultant ground shaking and noise awoke the area. Jose Lugo, 12, emerged from his father’s adobe on San Pedro Road, ran to the west bank of the now-empty river channel and watched the flood cutting a new channel along the far eastern side of the valley at the edge of the present Boyle Heights. The water cut away the base of the slope that defines the heights, and the morning revealed a sparkling white bluff of quartz sand and rounded white beach pebbles. It was known afterward as Paredon Blanco.

The 30-plus hours between the rain at the pueblo and the arrival of the flood indicates that a storm of biblical proportions had occurred at a high elevation and far away. One can postulate that an unfathomable deluge had taken place over the upper Big Tujunga Canyon.

The force of the water that poured through the Elysian Narrows that April night was sufficient to cut a river channel through forest and swamp all the way south from the Los Angeles Valley to the eastern portion of Rancho Dominguez near the present city of Carson. A huge inland lake formed within the bottom land area there. When it began to drain into the Pacific, it revealed the remains of thousands of animals.

Thus was born the “natural” L.A. river as we know it.

The new outlet to the sea drained the wetlands, and with the loss of the accompanying ground-water, the huge lowland forest disappeared in the following years.

The wetlands of Bolsa Chica and Newport are the sole surviving fragments of the original matrix, which may have been as large as 300 square miles.

Four years after the great flood, Kit Carson and Ewing Young made their first expedition into the Los Angeles Basin. The natural beauty was still such that Carson henceforth described Los Angeles as “truly a paradise on earth.”