GPS Control - Development Services

(Please see https://adacounty.id.gov/developmentservices for the latest version of this information)

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GPS Control

Ada County Bench Mark and HARN Based GPS Data

The file below is an excel file list of all the NGS Horizontal and Vertical Control in Ada County and the HARN based GPS surveys, contracted by the County as listed individually below. The columns lists control points in Local Coordinates, Latitude/Longitude, and Grid Coordinates. This list is also the numbering list for the Bench Marks and GPS data.

There are three different types of control information, where part of them are shown in different colors:

  • The original 1032 T-base survey points, which is the basis for the GIS Base Map, are shown at the (not true) 2700 ft. elevation.
  • All the NGS original horizontal and vertical control for Ada County, listed in the older datums, are shown in black.
  • HARN based GPS points are shown as red in color.

Download Ada County survey control list in MS Excel (2000) format

City of Boise GPS Bench Mark Survey

Download the Map and narrative (.pdf file) of the GPS project.  Consists of NGS control, FEMA control, and setting new benchmarks in Ada County.

OrbiTech INc. GPS Survey Control

ADA COUNTY MAPPING PROJECT 2000

Horizontal and Vertical Mapping Control surveyed for the Ada County Aerial Mapping Project of 2000. The project included points from the 1999 survey some of which no longer exist.
The project was surveyed by Shelby Griggs, PLS, of OrbiTech Inc. based in Prineville, Oregon.

A Complete Report of the “GPS PHOTO CONTROL FOR ADA COUNTY AERIAL MAPPING PROJECT 2000” is available in a .pdf format (7.4MB). Includes Station Data Sheets with location pictures and descriptions for each station.

Click here to download the report file  (7.4 Mb)

The control file consists of horizontal and vertical control points used for control of aerial mapping project of the county. Points are based on HARN control system of Ada County.
The file is comma delimited, and lists:

Point,
Latitude,
Longitude,
Grid North,
Grid East,
Local North,
Local East,
Elev (GIS 2700),
Calculated Elevation,
Calculated Difference,
Location (Section, Township, Range),
Description

Boise River Study

LIST OF BENCHMARKS FROM THE USGS/FEMA BOISE RIVER STUDY MAPPING PROJECT

Ada County now has over 100 benchmarks at the 1988 Datum east/west across the county along the Boise River corridor.  These benchmarks were part of an adjusted GPS control network for mapping the project and are accurate to +/-1cm horizontally and +/-2cm vertically.

These 3 .pdf files give the complete description of each station or benchmark and the sketches (graphics) of some of the stations.