Detail from CC Pierce's 1908 panorama of Eagle Rock Valley. (ERVHS)
The combined flow of Eagle Rock's underground streams during the dry season enters the Los Angeles River through the two culverts on the left. (Googlemaps)
Stormdrains under Eagle Rock Boulevard near Fair Park Avenue. (Bureau of Engineering)
FARMING IN THE LATE 1800s
The land where pioneer Eagle Rock settler Cromwell Galpin farmed was once ideal for crops: even without artificial irrigation.
The Los Angeles Times wrote about Eagle Rock, "It is surprising how long the soil here retains its moisture. We plant our vegetables after all the rains are over, and they mature and reach perfection without any irrigation... irrigation being unnecessary for anything except oranges."
Eagle Rock would not have been especially unique in this regard. Ludwig Louis Salvator wrote in 1876 of the "tablelands" of Los Angeles, that properly prepared soil could produce "nine good annual harvests out of ten, without irrigation, of castor oil beans, Indian corn, barley, alfalfa, potatoes, and various kinds of vegetables."
Galpin described how during even the particularly dry year of 1885, rain from the previous winter was still draining down from the surrounding hills; keeping his apple and apricot trees happy.
Galpin cites "lessened rainfall and better drainage" as reasons irrigation eventually became a pressing issue. As their livelihood depended increasingly on adequate access to water, farmers experimented with methods of boring wells and pumping water. This was no easy matter, and "[w]ith the change in available water, came changes in cultivation and in crops planted. Barley and oats gave way largely to garden truck and tomatoes, yielded to small fruits and berries such as strawberries."
According to www.waterfootprint.org, the average amount of water to produce these crops in cubic meters per ton is: barley (1388), oats (1597), tomatoes (184), strawberries (276).
Here's a more recent article on farming and rivers.