Gypsum Canyon

Gypsum Canyon covers 433.9 acres and holds 819 addresses on 408 parcels, at a median lot of 0.128 acres. Four hundred of those addresses carry a unit designator, and the whole polygon is zoned Planned Development or Open Space: 205.6 acres open space, 130.9 acres planned development and 1.1 acres commercial, spread across five of the city's planned development districts. Twenty-eight named streets run 5.03 miles inside the boundary and 137 of the 185 centerline segments are private, the highest private share in the city. The city flags 363 of the addresses as being in a homeowners association. The Santa Ana River Trail runs 0.76 miles inside the boundary, part of 1.54 miles of trail the city records here.

This is the wettest and least stable ground in Yorba Linda on the city's own layers. The flood layer places 224 acres in zone A and a further 103.1 acres in zone X500, and the state liquefaction zone layer covers 395.2 acres, effectively the whole polygon. The 2025 fire hazard severity layer rates 326.9 acres High and 81.7 acres Very High. Twenty-nine and a half acres at the eastern edge fall inside Chino Hills State Park, and the Susanna Bixby Bryant Museum sits on half an acre inside the boundary at 5700 Susanna Bryant Drive.

The street signs here are a roll call of the people who owned this ground. Susanna Bryant Drive, John Bixby Lane, Bernardo Yorba Circle and Rancho Santa Ana Road all sit inside the boundary, and so does the Susanna Bixby Bryant Museum. John Bixby bought this eastern end of Yorba Linda from Bernardo Yorba's widow in 1875 and named it Rancho Santa Ana after the river below, running cattle and sheep on it until his death in 1891.

Zanjero Lane is the sharpest name on the map. A zanjero was the man who tended the zanja, the irrigation ditch, and decided whose field got water and when. Old Pomegranate Road, Pomegranate Road, Citrus Ranch Circle and Cajon Canal Court keep the same farming record, while the rest of the streets are Mediterranean names at Anzio, Corsica, Malta, Nicosia, Palermo, Salerno and San Remo. The Santa Ana River Trail runs along the edge and 29.5 acres of Chino Hills State Park fall inside the community line.