Apr 27, 1776 118 212 Agua Escondida Agua Escondida, Malibu Creek State Park
Apr 28, 1776 119 213 Porciúncula River
Now called the LA River
Apr 29-May 1, 1776 120 214-216 Mission of San Gabriel Mission San Gabriel Arcángel
May 26-28, 1776 141 241-243 Real de la Cieneguilla
May 29, 1776 142 244 Los Cerritos
May 30, 1776 143 245 El Llano

Identification:
The river was given the name Porciúncula by the Portolá Expedition on August 2, 1769 in honor of a chapel near Asisi, which was rebuilt from ruins by Francis of Asisi and made the birthplace of the Franciscan Order of Monks in the fifteenth century. (D.G.)
Costanso: Aug 26 1769 Costanso in Spanish: Aug 26 1769 Map: showing the Porciúncula River

Definition: Three more leagues
Approximately 6 miles calculated according to the average length of a league as measured by Captain Anza. A league is a unit of measurement — the distance a horse could walk in an hour. Today it is generally considered to be approximately 2.5 miles, but since it was a measurement of distance travelled over time, it tended to vary according to the conditions of both the horse and the terrain. Padre Font’s leagues averaged 2.33 miles for the entire expedition and Captain Anza’s averaged just slightly under 2 miles. (D.G.)
Definition: A portesuelo is a “small pass between hills.” (D.G.)
Map: showing Portezuelo

Wednesday, February 21, 1776
Wednesday, February 21 . — At half past eleven, when everything was ready for the march, I set forth with seventeen of the soldiers and the same number of the families destined to remain in this California, besides six of my company . four of these last are remaining here to await Lieutenant Moraga , as has been said, and also to escort the cattle belonging to the colonists . I set out on the regular road to Monte Rey , which we followed for a little more than a league to the southwest. Continuing for another league to the west-southwest, we crossed the Porciúncula River . After this we made three more leagues , traveling until five o’clock in the afternoon, having marched five and a half hours, when we halted at El Portezuelo , where the night was passed. Notwithstanding that for a number of days past it has not rained very hard, the road has been so heavy that many of the mules which carried the loads fell down. — From Tubac to El Portezuelo, exclusive of the distance traveled in going to and returning from San Diego , 203 leagues .

Expanded Diary of Pedro Font
2/21/1776
Wednesday, February 21.—I pronounced the blessing with ashes and said Mass, and in it spoke a few words to the people who were remaining and to those who were going, for some of them wept and were displeased with this separation. With the gospel of the day I confirmed all that from the beginning of the journey I had said to them in the talks which I had made to them; that is, that they came to suffer and to set an example of Christianity to the heathen, etc. It all reduced itself to exhorting one and another to repentance for their sins, and to patience in their trials, etc., etc.
We set out from the mission of San Gabriel at half past eleven in the morning, and at half past four in the afternoon we halted at the Puertezuelo, having traveled six leagues, two to the west with some turns to one side and the other, and the rest to the west-northwest. At two leagues we crossed the Porciúncula River, which carries a great deal of water and, running toward the Bay of San Pedro, spreads out and is lost in the plains a little before reaching the sea. The land was very green and flower-strewn. The road has some hills and many mires caused by the rains, and for this reason the pack train fell very far behind. At the camp site there is permanent water, though little, and plenty of firewood. On the left at a distance runs the chain of hills which form the Bay of San Pedro in the sea, and on the right the Sierra Nevada, and another rough and long one which is in front of it.

[Footnote 237]—Six leagues.

HISTORY OF THE Porciuncula River, now the LA River
History
Los Angeles River at Griffith Park, c. 1898–1910
The river provided a source of water and food for the Tongva people prior to the arrival of the Spanish.[16] After the establishment of Mission San Gabriel in 1771, the Spanish referred to all of the Tongva living in that mission’s vicinity as Gabrieliño. The Gabrieliños were hunters and gatherers who lived primarily off fish, small mammals, and the acorns from the abundant oak trees along the river’s path. There were at least 45 Gabrieliño villages located near the Los Angeles River, concentrated in the San Fernando Valley and the Elysian Valley, in what is present day Glendale.
In 1769, members of the Portolà expedition to explore Alta California were the first Europeans to see the river. On August 2, the party camped near the river, somewhere along the stretch just to the north of the Interstate 10 crossing near downtown Los Angeles. Fray Juan Crespi, one of two Franciscan missionaries traveling with Portolà, named it El Río de Nuestra Señora La Reina de Los Ángeles de Porciúncula. Crespi chose that name, which translates as The River of Our Lady Queen of the Angels of Porciuncula, because it was the name of a special annual feast day for the Franciscans, which the Portolà party had celebrated the previous day. The river was thereafter referred to as the “Porciuncula River”. In later years, the “Los Angeles” part of Crespi’s lengthy name won out.[17]

Ed Hunt, Griffith Park policeman, in the Los Angeles River, 1911
The river was originally an alluvial river that ran freely across a flood plain that is now occupied by Los Angeles, Long Beach and other townships in Southern California. Its path was unstable and unpredictable, and the mouth of the river moved frequently from one place to another between Long Beach and Ballona Creek. In the early 19th century, the river turned southwest after leaving the Glendale Narrows, where it joined Ballona Creek and discharged into Santa Monica Bay in present Marina del Rey. However, this account is challenged by Col.

J. J. Warner, in his Historical Sketch of Los Angeles County:
“…until 1825 it was seldom, if in any year, that the river discharged even during the rainy season its waters into the sea. Instead of having a river way to the sea, the waters spread over the country, filling the depressions in the surface and forming lakes, ponds and marshes. The river water, if any, that reached the ocean drained off from the land at so many places, and in such small volumes, that no channel existed until the flood of 1825, which, by cutting a river way to tide water, drained the marsh land and caused the forests to disappear.”[18]

Prior to the Great Flood of 1862, it was joined by the San Gabriel River in present-day Long Beach, but in that year the San Gabriel carved out a new course 6 miles (9.7 km) to the east, and has discharged into Alamitos Bay ever since.
Placing of concrete in a section of the counterforted channel wall on the left bank just above 26th Street in the city of Los Angeles, 1938.

Until the opening of the Los Angeles Aqueduct in 1913, the Los Angeles River was the primary water source for the Los Angeles Basin, but much of its channel had extremely low discharge except during the winter rains.

You can visit National Park Service for more information; http://www.nps.gov