That book is simply (and no doubt inadvertantly) wrong, I'm sure. Here's the beginning of my own notes on Spring St., gathered from various sources over the years. It was probably only playfully called "Danger St." due to what's detailed in the latter part of this:
"Spring Street, the sometime “Calle Primavera” said to have been named by surveyor Ord for his beloved Maria de la Trinidad Serafina Ortega (married name de la Guerra), whom he referred to as his “Springtime” (“Primavera”); before realignment in the 1920s, it followed a diagonal running between close to its 1st St. corner and the intersection of Temple St./Main St., which was the path of the original Native American trail skirting the hills; 1846, the residence of Narciso Botello was on this street; January 2, 1858, published (
Los Angeles Star): “Owing to inattention to the state of the sewerage, a row of houses on Spring street were inundated by the flood, causing considerable annoyance but no serious damage”; January 16, 1858, published (
Los Angeles Star): “On Wednesday we were visited by a very heavy rain, which lasted for several hours. It fell in torrents, causing a flood in our streets, and almost inundating a row of buildings on the west side of Spring street, creating no little consternation among the inhabitants. This is a most unfortunate block of buildings, as the water from the adjacent hills flows down on them, and keeps the inmates on the look-out during each heavy rain."
Edit add: It might be worth adding that it wasn’t until the 1840s that the city began to look into the interesting question of giving the streets names--not naming streets was not unusual in California; Davis mentions that neither did San Francisco’s streets have any names in the mid-1840s (William Heath Davis,
Seventy-Five Years in California, p. 115).