Bench Mark System
The City of San Luis Obispo Bench Mark System was established to provide a consistent datum plane for architects, engineers and builders to ensure proper design and construction of improvements. Over 400 benchmarks have been established throughout the City. These Elevations are published for general use in a document titled: "Bench Mark System".

The majority of the bench marks were established in 1979 & 1980 based on the Sea Level Datum of 1929. Since then the elevations have been adjusted to the NAVD 1988 datum. The benchmarks have not been resurveyed since originally established, except as noted in the publication.

The current edition (January 2007) is available for download online at no charge. Hard copies may be purchased for $5 at the Public Works counter, 919 Palm Street.

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Horizontal Control Network
During the summer of 1990, the City of San Luis Obispo hired a consultant to establish a horizontal control network using the Global Positioning System (GPS). The purpose for the network was to establish a precise and reliable survey control relative to the California Coordinate System, Zone 5 also known as the “North American Datum of 1983” or “NAD 83.”

The network, which includes 15 primary points and 132 secondary points, was established as control for the City’s Geographic Information System (GIS) as well as to provide a reliable form of reference for the private surveying community.  In addition, the network was re-adjusted to the California High Density Precision Network (HPGN) known as the “1991.35 epoch adjustment of the North American Datum of 1983” also referred to as “NAD 83 (1992).”

The current edition (2007) is available for download online at no charge. Hard copies may be purchased for $5 at the Public Works counter, 919 Palm Street.

View online  (PDF, 828k)