BOAC, if you examine the VFR sectional chart for the area, you will see San Carlos airport just to the south of the San Mateo bridge. It is a reasonably busy general aviation strip, its traffic pattern altitude is listed as 805' MSL.
1900' puts you a rounded-up 1000' above the San Carlos traffic pattern, which complies with the 3-mile lateral/1000' vertical approach separation criteria.