Surveyor's How-To Guide
This guide collects the official government resources, databases, and reporting procedures most useful in PLSS monument work, plus the formal report workflow built into this tool. It is written for working surveyors and field technicians — practical steps, not bureaucratic summaries.
1. GLO Field Notes and Township Plats
The General Land Office (GLO) conducted the original Public Land Survey between roughly 1785 and the early 1900s. Their original field notes and township plats are the authoritative legal record of what the original surveyors found, measured, and set at each corner. They describe bearing trees, witness corners, water crossings, distances, and the condition of monuments at the time of survey.
If you know what the original surveyor described at a corner, you can verify that the monument you found is the right one — and explain discrepancies between the monument position and modern GPS coordinates.
How to find field notes for a specific township:
2. NGS Survey Marks and Datasheets
The National Geodetic Survey (NGS) maintains a national database of geodetic control marks — monuments with published coordinates in the national reference frame (NAD83). These include triangulation stations, bench marks, CORS stations, and other survey control. Each mark has a permanent identifier (PID) and a datasheet showing its coordinates, condition, recovery notes, and history.
2.1 Finding a Mark Near a Corner
2.2 Reading a Datasheet
Every NGS datasheet contains:
- PID — permanent 6-character identifier (e.g. AF1234)
- Designation — the mark's name (e.g. "LINCOLN 1962")
- Coordinates — NAD83 latitude/longitude and/or NAVD88 orthometric height
- Setting — what the monument is set in (concrete, bedrock, etc.)
- Stability — NGS's assessment of monument stability
- Condition — last known condition: Good, Poor, Not Found, or Destroyed
- Recovery notes — field notes from every recovery visit with date and surveyor name
2.3 Reporting a Recovery to NGS
If you visit an NGS mark — found it, couldn't find it, or found it in a different condition — you can submit a recovery report. Anyone can submit. Licensed surveyors' recoveries carry more weight but public recoveries are accepted and appear on the datasheet permanently, credited to you by name.
What to include in a recovery report:
- Condition — Good, Poor, Not Found, or Destroyed (only use Destroyed with irrefutable evidence)
- Current appearance — what it looks like now, any damage or changes
- Distance and direction from nearby fixed objects — curbs, utility boxes, drain covers, trees
- Your name, contact information, and license number
- Date of recovery
- Photos — strongly encouraged
2.4 Submitting a New Mark to NGS
To submit a new monument to the NGS database or contribute GPS-observed positions to the geodetic network, use NGS's OPUS Projects system.
3. BLM PLSS Data
4. State Plane Zones — Why They Matter
California is divided into six State Plane coordinate zones, each using a different Lambert Conformal Conic projection. Choosing the wrong zone gives you completely wrong coordinates — potentially miles off at the edges of a zone. The zone selection in the Q/QQ Lookup controls:
- Which projection parameters are used to compute Grid Northing and Easting
- The central meridian used for convergence angle calculation
- The false northing and easting origin (what number the coordinates start from)
- The scale factor at the projection center — which affects the CSF
| Zone | Coverage | Typical Use |
|---|---|---|
| CA Zone 1 | Del Norte, Humboldt, Siskiyou, Trinity, Modoc | Eureka and far north CA work |
| CA Zone 2 | Sacramento Valley, Sierra Nevada foothills, Lake Tahoe area | Most MDM monument work — Sacramento, El Dorado, Placer Counties |
| CA Zone 3 | San Francisco Bay Area south to Fresno | Bay Area and Central Valley work |
| CA Zone 4 | Los Angeles, Santa Barbara, central coast | Southern CA coastal work |
| CA Zone 5 | San Bernardino, Riverside, inland San Diego | Inland southern CA, SBM meridian work |
| CA Zone 6 | San Diego coastal area | Coastal San Diego work |
For most work in the Sacramento, El Dorado, and Placer County area under the Mt Diablo Meridian, CA Zone 2 is correct. If your coordinates look right in Google Maps but are offset by tens of thousands of feet from what AutoCAD shows, check the zone selection first.
5. Magnetic Declination
Magnetic declination is the angle between magnetic north (where a compass points) and true north (toward the geographic North Pole). It varies by location and changes annually as the Earth's magnetic field slowly shifts.
The tool computes declination from the BGS World Magnetic Model 2025 (WMM2025) for the exact corner location and today's date. This is the same model used by the National Geospatial-Intelligence Agency and is valid through 2030.
Using declination in the field: Under heavy tree cover where GPS is degraded, a compass bearing can be converted to a true bearing by applying the declination. In California (east declination): True bearing = Magnetic bearing − Declination. Then apply convergence to get the grid bearing for your total station.
6. CORS Stations
Continuously Operating Reference Stations (CORS) are permanently installed GPS receivers that broadcast real-time corrections. Your RTK GPS receiver connects to a nearby CORS station to achieve centimeter-level accuracy. The tool shows the nearest CORS and CRTN (California Real Time Network) stations as blue markers on the map after every lookup.
7. Filing a Corner Record
Under B&P §8773, a Corner Record must be filed with the county surveyor when a PLSS corner is found and used as control in a survey. The Corner Record generator in this tool produces a compliant document — print it and deliver it to the appropriate county.
7.1 El Dorado County
Survey Division: 360 Fair Lane, Placerville, CA 95667
Phone: (530) 621-5981 · GIS: parcel.edcgov.us
Fee: $25 per corner · GIS help: (530) 621-5719
7.2 Placer County
Surveyor's Office: 3091 County Center Drive, Suite 130, Auburn, CA 95603
Phone: (530) 886-3000
Clerk-Recorder: 3715 Atherton Road, Rocklin, CA 95765 · (530) 886-5600
GIS: placer.ca.gov/2842/GIS-and-Online-Maps
7.3 Sacramento County
Engineering — Surveys Division: 827 7th Street, Room 101, Sacramento, CA 95814
Phone: (916) 874-6576 · Email: surveyquestions@saccounty.gov
Online payment: govhub.com/sacramento/surveyfees
GIS: generalmap.gis.saccounty.gov/JSViewer/county_portal.html
Review timeline: First review 20 business days, subsequent reviews 10 business days
7.4 Other Counties
Every California county with a surveyor's office accepts Corner Record filings. For counties not listed above, contact the county surveyor directly. The California Land Surveyors Association (CLSA) maintains a directory of county surveyors at californiasurveyors.org.
8. Parcel and APN Lookup
The tool's Parcel Lookup tab works from either a street address or an APN, and covers Placer, El Dorado, and Sacramento Counties. The county sites below are where to go for anything the tab does not return — most importantly easements, which no county in this coverage area publishes as GIS data.
8.1 Researching Easements
Easements are not available from any of the parcel services this tool queries, so an APN lookup will not surface them. Two places to look instead:
- The assessor map. The parcel detail panel links the book-page map as a PDF. Assessor maps commonly draw easement lines even though the easements are not published as data. This is the fastest first look, but the map is prepared for assessment purposes and does not establish boundaries.
- The county Clerk-Recorder. Recorded easements live in official records alongside deeds, liens, and judgments. Searches run by party name, recording date, or document number — not by APN — so start from the chain of title rather than the parcel number. The
Recorded DocumentandAssessor Book-Pagefields in the parcel detail give you an entry point.
Neither source is a substitute for a title report. Use them to scope the research, then order title work before relying on an easement for a boundary determination or a set.
9. Identifying the Correct Meridian
Three principal meridians cover California. Choosing the wrong one produces a lookup result in a completely different part of the state. The tool lists all three in the meridian dropdown — select the one that matches where you are working.
| Meridian | Abbrev. | Coverage |
|---|---|---|
| Mount Diablo Meridian | MDM | Most of California — all of Northern and Central California, most of the Sierra Nevada, Sacramento Valley, Bay Area |
| Humboldt Meridian | HUM | Northwestern California only — Del Norte, Trinity, and Humboldt Counties. If you're working near Eureka, use HUM. |
| San Bernardino Meridian | SBM | Southern California — San Bernardino, Riverside, most of San Diego, parts of Los Angeles and Orange Counties |
10. Closing Sections and Government Lots
Closing sections occur at the western and northern edges of townships because the PLSS survey was laid out from east to west and south to north. Accumulated measurement error is absorbed at these edges — resulting in sections that are not exactly one mile square. The GLO assigned government lot numbers to the irregular portions.
Which sections are potentially closing sections:
- Northern tier: Sections 1–6 (north edge of township)
- Western tier: Sections 6, 7, 18, 19, 30, 31 (west edge of township)
Practical implications:
- Standard QQ corners may not exist in the irregular portion — there may be no 40-acre parcels to corner
- Lot corners replace QQ corners — the lot boundary lines are the controlling lines
- Lot dimensions and acreages are in the original GLO field notes and plats — they are not mathematically predictable
- A section may be both a closing section and contain some standard QQ geometry if the irregular portion is only a fraction of the section
- Some closing sections were never divided into lots — the irregular portion was simply absorbed into adjacent parcels or left as one irregular parcel without lot numbering
11. Unsurveyed Townships — Ranchos and Withdrawals
When the Q/QQ Lookup finds no BLM data for a township, the tool performs a township scan. If the scan also finds nothing, the land was almost certainly never subdivided by the GLO under the PLSS system. Two main historical reasons explain this:
11.1 Mexican Land Grants (Ranchos)
Under the Treaty of Guadalupe Hidalgo (1848) and the California Land Act of 1851, the United States was obligated to honor valid Mexican land grants. Land that was already privately owned under a confirmed rancho grant never entered the public domain and was therefore never subdivided by the GLO. The GLO surveyed only the public domain — not private land.
This means that in rancho territory, no PLSS corners were ever set in the interior of the township. The exterior township lines may have been run, but the interior was left blank because it was private land before the survey system arrived.
What to do in rancho territory:
- Search for a private land claim survey filed under the rancho name — not by township and range
- The GLO Records at glorecords.blm.gov contain private land claim surveys — search by state and use the document search rather than the township/range filter
- County recorder records may contain the original diseño (rancho map) and the US Land Commission confirmation documents
- Do not expect to find PLSS monuments in the field — they were never set
- Any survey control in the area will be local government monuments, road centerline monuments, or tract map control — not federal PLSS corners
11.2 Military Reservations and Federal Withdrawals
Land that was reserved for military use, national parks, or other federal purposes before the GLO survey may have partial data — exterior lines and perhaps some perimeter sections — but no interior survey. The federal government withdrew the land from public domain disposal and therefore had no reason to subdivide it into 40-acre parcels for homesteading.
Examples in the Sacramento area: McClellan Air Force Base (now McClellan Business Park) and Mather Air Force Base (now Mather Airport) created gaps in the MDM survey in the T9N–T10N area east of Sacramento.
11.3 What To Do When the Township Is Blank
- Check the township scan banner — it will explain whether the pattern suggests rancho or military withdrawal
- Contact the county surveyor — they may have locally established control not in the BLM database, or knowledge of historical surveys in the area
- Search glorecords.blm.gov for private land claim surveys by state (California) rather than by township
- Check county recorder records for rancho maps and early subdivision plats that predate the PLSS
- If you need to establish control from scratch, start from the nearest confirmed PLSS corners in adjacent townships and work inward — document your methodology thoroughly in a TRR
12. Monument Recovery Procedures
12.1 Visual Recovery
A visual recovery is when a monument is found above grade and identified by direct observation — no digging, no electronic equipment. The monument is simply there and visible. This is the best case scenario and the most defensible recovery — you can see it, photograph it, and describe it in plain terms.
For a visual recovery, log the find with:
- Equipment: Visual recovery — select this in the equipment panel
- Height above grade
- Monument type and condition
- Any cap markings, stamp, or identification
- Reference ties to nearby fixed objects
- Photographs from multiple angles
12.2 When You Find an Unmarked Monument
An uncapped pipe, unmarked rebar, or plain iron post with no identification presents a challenge — you cannot definitively identify it as the corner without corroborating evidence. The standard of evidence for identification without a cap or stamp typically requires:
- Positional agreement with the computed coordinates (within the expected BLM displacement)
- Physical agreement with the GLO field notes description of the original monument type
- Agreement with reference tie distances from the field notes or prior Corner Records if any exist
- Absence of conflicting monuments nearby
- Professional judgment — document your reasoning explicitly in your MFR and Corner Record
When the evidence is strong but not conclusive, your professional judgment as the licensed surveyor determines the identification. Document that reasoning so future surveyors understand the basis for your conclusion.
12.3 When You Cannot Find the Monument
A Not Found result is valuable professional information — it tells future surveyors where to search and what was tried. A thorough Not Found log entry should describe:
- The search area — radius searched, depth probed
- Equipment used — metal detector sweep, probe rod depth, shovel test
- Terrain and access conditions — pavement, vegetation, water, development
- Why you believe it's not there — paved over, graded away, in an inaccessible location
- What would be needed to continue the search — excavation permit, access to private property, utility clearance
13. Formal Reports — Workflow
Formal survey reports in this tool sit above the informal Monument Log as the professional documentation layer. The Monument Log captures field intelligence quickly. A formal report certifies that intelligence under a license number and makes it available to the broader professional community.
13.1 Monument Field Report (MFR) Workflow
The MFR is the formal version of a Monument Log entry. It documents the complete field research story — what was searched for, how, what was found, its physical description, reference ties, and the surveyor's professional conclusion.
- Complete the field work and log a Monument Log entry immediately after the search
- Return to the office and open the Reports tab
- Click + MFR — the form pre-fills from the current lookup
- Write the field journal — describe the complete search narrative. Be specific about what you found, where exactly it was, its physical appearance, and what corroborates the identification
- Enter a one-line summary (appears in the report list)
- Add photographs if taken
- Save as Draft
- Have a Licensed Surveyor or System Architect review and finalize the report
- If the monument was used as control, generate a Corner Record and file with the county
13.2 Township Research Report (TRR) Workflow
A TRR documents your research into a township that returned no or partial BLM data. It is the professional record of what was investigated, what the historical explanation is, and what approximate positions were derived.
- Run the Q/QQ Lookup — if the township scan fires, review the results and banner explanation
- Research glorecords.blm.gov for private land claim surveys or partial township data
- Contact the county surveyor to ask about local records
- Open the Reports tab, click + TRR
- Document all research steps — what sources were checked, what each returned
- Explain the historical context — rancho, military withdrawal, or other reason for the gap
- Record any approximate positions derived from neighboring sections — explicitly noting the basis and accuracy estimate
- Include the mandatory disclaimer: positions are approximate and not for use as survey control without field verification
- List recommended next steps for future work in the area
13.3 Derived Position Report (DPR) Workflow
A DPR is a short, technical companion to a TRR. It documents the specific mathematics behind an approximate corner position computed from adjacent section polygon vertices.
- Complete the TRR first — the DPR references it
- Click + DPR in the Reports tab
- List which neighboring sections were queried and what each returned
- Identify the specific polygon vertices used as the basis for the derived position
- State the derived position: lat/lon and Grid N/E
- State the accuracy estimate explicitly — typically ±100–200 feet given BLM polygon displacement
- Include the mandatory disclaimer: no monuments are known to exist at this position; not for use as survey control
13.4 Supervisor Review of Draft Reports
Draft reports created by Survey Technicians, Field Technicians, or LSTTs require review and finalization by a Licensed Surveyor before they carry professional weight. This is the intended workflow:
- Field staff creates a Draft MFR with complete field narrative and photos
- Licensed Surveyor logs in and opens the Reports tab
- Reviews the draft — verifies corner designation, checks physical description against GLO field notes, confirms reference ties are adequate
- Corrects any errors in the draft (corner code, description, measurements)
- Clicks Finalize — enters license number and confirms certification
- Report is locked and becomes publicly visible as a Final document
14. California Legal Obligations for Surveyors
14.1 B&P §8761 — Professional Responsibility
All survey documents — field notes, plats, maps, Corner Records, and formal reports — must bear the name, signature, and license number of the responsible licensed land surveyor or registered civil engineer. This applies to all documents prepared under a surveyor's supervision, including documents prepared by technicians.
Tool implementation: The finalization step embeds the license number into the report permanently. Only users with verified licenses can finalize. LSIT-generated Corner Records trigger an email notification to the supervising Licensed Surveyor.
14.2 B&P §8771 — Setting Monuments
A licensed land surveyor must set or reset monuments at the corners of any survey they make. Monuments must be permanent and durable. The surveyor must file a Corner Record for any monument set or reset in connection with a survey. The monument must be identified with the surveyor's license number.
Tool implementation: The Corner Record generator produces a compliant document pre-filled with the surveyor's credentials from their profile. The condition field tracks whether rehabilitation is required under AB3253.
14.3 B&P §8773 — Corner Records Required
A Corner Record shall be filed with the county surveyor when:
- A licensed land surveyor finds a monument and uses it as control in any survey — regardless of its condition
- A monument is set or reset in connection with any survey
- A surveyor performs a retracement of recorded lines where no material discrepancies are found and sufficient monumentation is recovered
Filing a Corner Record does not relieve the surveyor of the responsibility to file a Record of Survey if one is required under §8762.
14.4 AB3253 (2024, Chapter 588) — Monument Condition Obligation
Signed September 25, 2024, effective January 1, 2025 through January 1, 2029. Adds B&P §8771.6: when a licensed land surveyor or registered civil engineer uses any monument as control in a survey, and that monument's physical condition is less than permanent and durable, they must reconstruct or rehabilitate it so that it remains permanently fixed and can be located in the future.
What changed from prior law: Previously the rehabilitation obligation only applied when filing a Corner Record for a corner you were specifically working on. AB3253 extends this to any monument used as control — including an incidental tie to a nearby corner for orientation.
Practical implications:
- If you GPS to a section corner for RTK control and the cap is missing or the pipe is bent — you are now required to rehabilitate it before completing your survey
- The condition field in the Monument Log and MFR is now a legal trigger. "Poor" or "Damaged" means obligation.
- Rehabilitation must be accompanied by a Corner Record filing per §8771
- This provision expires January 1, 2029 — it may be extended, modified, or made permanent
14.5 California Consumer Privacy Act (CCPA/CPRA)
This tool stores personal data about users — names, license numbers, email addresses, and field visit coordinates. California Civil Code §1798.100 et seq. imposes obligations on how that data is handled.
What the tool does to comply:
- Users can view and update their own data via the profile page
- Parcel owner information is not stored — the Parcel Lookup retrieves APN data on demand and displays it only, never retaining owner names
- Shared monument records expose professional identity intentionally — finder name and license number in shared records is appropriate professional accountability, consistent with the public nature of Corner Record filings
- Audit log data is internal — accessible only to organization administrators
What users should know: Your name, license number, and field notes will appear in Monument Search results visible to all logged-in surveyors across all organizations when you log a Found or Partial monument. Do not include private client information or sensitive site descriptions in public field notes.