USGS Earth Explorer

This dataset represents natural color, leaf-off, 1 foot high-accuracy orthorectified aerial imagery, acquired by the Los Angeles Regional Imagery Consortium (LAR-IAC) in winter 2010/2011, and made public with the partnership of the US Geological Survey (USGS). The DEM represents bare earth, whereas a related product (DSM) contains elevations and includes buildings, [...]]]>

USGS Earth Explorer

This dataset represents natural color, leaf-off, 1 foot high-accuracy orthorectified aerial imagery, acquired by the Los Angeles Regional Imagery Consortium (LAR-IAC) in winter 2010/2011, and made public with the partnership of the US Geological Survey (USGS).  The DEM represents bare earth, whereas a related product (DSM) contains elevations and includes buildings, vegetation, and roads, as well as natural terrain features, whereas .

This data was down-sampled from the 4-inch orthophotography created as part of LAR-IAC.  Detailed product information is contained in the LAR-IAC Product Guide.

To get this data, you can do one of the following:

Use either the National Map Viewer (nationalmap.gov/viewer) or the EarthExplorer (EarthExplorer.usgs.gov) sites to access this data.

If you have questions please contact the US Geological Survey Representative at the bottom of this page (Drew Decker).

About LAR-IAC

We highly recommend that you visit the LAR-IAC Project Website to find a rich source of information about the data and the LAR-IAC program.  The site includes project documents, full FGDC compliant metadata, data downloads of related GIS used to complete the project, sub-licensing information, sample imagery and data, and information about the 2006 acquisition.

National Map

The Los Angeles Region Imagery Acquisition Consortium (LAR-IAC) Program is a collaborative acquisition program for digital aerial imagery data which has included the participation of 10 County departments, 30 municipalities, and four other public agencies.

The consortium is a model for regional cooperation that improves the quality, access, and cost-effectiveness of high resolution digital aerial imagery. Knowledge transfer is increased through consortium program meetings, user groups, and various workshops that have been established in conjunction with the project. The imagery acquired will enable all participating jurisdictions to leverage this key geographic information asset for numerous decision support and business applications, thereby facilitating the effective and efficient delivery of services.

natgrid_100m_mj100k

natgrid_100m_mt100k

natgrid_100m_lu100k

100 Meter National Grid for Los Angeles County

Layering

The US Geological Survey has made its standard topo maps available for download through The National Map Viewer. NOTE – through research I have found that the USGS topo Store is a better place to go to download the maps. Click here to go to the store

There are now in [...]]]>

Layering

The US Geological Survey has made its standard topo maps available for download through The National Map Viewer.  NOTE – through research I have found that the USGS topo Store is a better place to go to download the maps.  Click here to go to the store

There are now in .pdf format, which is a digital file format which has a couple of unique capabilites:

1. Layers can be turned on and off – see the snapshot to the right.
2. There is an ortho image behind the map now (that’s cool)
3. I believe there are some very cool tools within a plugin for Acrobat called “geo-pdf” which adds GIS capabilities.

Pasadena Quad

US Topo is the next generation of digital topographic maps from USGS.  Arranged in the traditional 7.5-minute quadrangle format, digital US Topo maps are designed to look and feel like the traditional paper topographic maps for which the USGS is so well known. At the same time, US Topo maps provide modern technical advantages that support wider and faster public distribution and enable basic, on-screen geographic analysis for all users.  US Topo maps are available free on the Web. Each map quadrangle is available as a GeoPDF® file created from key layers of geographic data – orthoimagery (2010 NAIP), roads, geographic names, contours, and hydrographic features – found in The National Map, which is a nationwide collection of integrated data from local, state, federal, and other sources.  The National Map data layers make up the US Topo products and much of these data are available for download through The National Map Viewer (nationalmap.gov/viewer).  Stay tuned for additional emails soon from us about these digital resources (data download and consumable map services).

Note that California also played a significant role in developing end user requirements for the US topo.  There were a number of interviews and workshops that took place across the state in 2008 and 2009.  These gathered information from many of you as private sector, educational, and local, state, and federal government customers on the direction for future USGS mapping products and services – including US Topo.

The US Topo News Release refers to the USGS Store at the place to go for the new maps.  Visit the USGS Store site at store.usgs.gov.  Then click on the “Map Locator & Downloader” in the center of the page.  From there you can locate your favorite maps in CA by searching by map or place name or by pan/zoom on the viewer.  Maps are available as GeoPDF® files for free download.  Besides the map downloads at the Store, we have lots of information on US Topo and related products.

1. US Topo information is online at
http://nationalmap.gov/ustopo/        (main page)
http://pubs.usgs.gov/fs/2009/3108/      (fact sheet)

2. A Users Guide to US Topo and other USGS GeoPDF® products is available here:
http://nationalmap.gov/ustopo/quickstart.pdf

3. There is a good FAQ section too.  It has information for queries such as bulk data downloads (Q2 under Product Access and Download ) and GIS formats (Q6 under Product Use).  See:
http://nationalmap.gov/ustopo/faq.html

4. News items and tweets on the USGS National Geospatial Program are at
http://nationalmap.gov/tnm_news.html
http://twitter.com/#!/USGSTNM

5. We welcome your comments and suggestions about new US Topo maps.  Please submit comments online at
http://nationalmap.gov/ustopo/ustopo_feedback.html

While downloading US Topo maps and looking around the USGS Store. you will also notice that the digital historical topographic maps for California are available.  We had announced the historical topo maps release before but this is a good time for a reminder.  The historical map collection includes over 13,700 historic maps across the state with some maps dating back over 100 years.  All published map scales are available, including: 7.5-minute (1:24,000), 15-minute (~1:63,000), 30-minute (1:100,000), and 1×2 degree (1:250,000).  For dataset needs that cover the entire state, please contact Carol or Drew.

Like with US Topo, we have lots of additional information on the historical map collection and the program that produced them.  For example:

1. Information about the USGS historical topographic map collection and the historical quadrangle scanning project can be found here:
http://nationalmap.gov/historical/     (main page)
       http://pubs.usgs.gov/fs/2011/3009/      (fact sheet)

2. We have a 19 minute video from the September 2011 International Map Trade Association Conference on distribution of USGS historical topo maps:
http://gallery.usgs.gov/videos/465

3.  See a press release on the historical topographic map collection.  The article is from late 2011 but provides good additional information on the project:
http://www.usgs.gov/newsroom/article.asp?ID=3024

USGS CLICK site

This site is a valuable resource for downloading LIDAR and Elevation data, including recent hi-resolution LIDAR along the coastlines of the United States.

Click to go to the USGS Center for LIDAR Information Coordination and Knowledge (CLICK).

CAMS Data (October 2011)

Current data date: August 2012 – we will be releasing new versions of this data periodically.

Important note: This file is not final – it is an intermediate step and should be used with the understanding that further work is being performed.

Description

The LA County Street Center TIGER [...]]]>

CAMS Data (October 2011)

Current data date: August 2012 – we will be releasing new versions of this data periodically.

Important note: This file is not final – it is an intermediate step and should be used with the understanding that further work is being performed.

Description

The LA County Street Center TIGER road file is a street centerline network in development by Los Angeles County to move toward a public domain street centerline and addess file.  This dataset can be used for two purposes:

1. Geocoding addresses in LA County – this file currently geocodes > 99.5% of the addresses in our test files (5,000 out of 8 million addresses) using the County’s geocoding engines.
1. This last statement is important - the County splits the street names and addresses differently than most geocoders.  This means that you cannot just use this dataset with the standard ESRI geocoding (US Streets) geocoding engine.  You can standardize the data to resolve this, and we will be publishing the related geocoding rules and engines along with instructions on how to use them, in the near future.  Please review the data fields to understand this information.
2. Mapping street centerlines in LA County – note that the street types in this file are not fully updated yet.  Use with caution.

History

LA County has historically licensed the Thomas Brothers Street Centerline file, and over the past 10 years has made close to 50,000 changes to that file.  In order to provide better opportunities for collaboration and sharing among government entities in LA County, we have embarked upon an ambitious project to leverage the 2010 TIGER roads file as provided by the Census Bureau and upgrade it to the same spatial and attribute accuracy as the current files we use.  This effort is part of the Countywide Address Management System (click the link for details).

Processes

The County downloaded and evaluated the 2010 TIGER file (more information on that file, including download, is at this link).  The evaluation showed that the TIGER road file was the best candidate to serve as a starting point for our transition.

Since that time, the County is moving down a path toward a complete transition to an updated version of that file.  Here are the steps that have been completed and are anticipated.

1. Upgrade the geocoding accuracy to meet the current LA County street file licensed from Thomas Brothers.  This has been completed by the Registrar/Recorder (RRCC) – matching rate have improved dramatically. COMPLETE
2. Develop a countywide street type code to reflect various street types we use.  We have used various sources, including the Census CFCC and MTFCC codes to develop this coding.  The final draft is here –  Final Draft of Street Type Codes for CAMS (excel file)
3. Update the street type information to support high-quality cartography.  IN PROGRESS - we have completed an automated assignment for this, but RRCC will be manually checking all street segments in the County to confirm.
4. Load this dataset into our currrent management system and begin continuing maintenance.

Here are some useful links:

NHGIS Site

The National Historical Geographic Information System (NHGIS) website recently is an incredibly valuable tool for historic demographics information. You just need to register.

From their site:

The National Historical Geographic Information System (NHGIS) provides, free of charge, aggregate census data and GIS-compatible boundary files for the United States between [...]]]>

NHGIS Site

The National Historical Geographic Information System (NHGIS) website recently is an incredibly valuable tool for historic demographics information.  You just need to register.

From their site:

The National Historical Geographic Information System (NHGIS) provides, free of charge, aggregate census data and GIS-compatible boundary files for the United States between 1790 and 2000. NHGIS offers the following options to obtain data:

The Census Bureau (http://www.census.gov/) maintains geographic boundaries for the analysis and mapping of demographic information across the United States. Every 10 years the Census Bureau counts the population of the United States as mandated by Constitution. The Census Bureau releases the results of this county as demographic data with [...]]]> Census Geography Background

The Census Bureau (http://www.census.gov/) maintains geographic boundaries for the analysis and mapping of demographic information across the United States. Every 10 years the Census Bureau counts the population of the United States as mandated by Constitution. The Census Bureau releases the results of this county as demographic data with geographic identifiers so that maps and analysis can be performed on the US population.

For a quick introduction to Census geography, click the thumbnail on the right which shows the relationship between Census Blocks, Block Groups, Tracts, and Counties.

For detailed information about the Census Geography, here are some other links:

• Geographic Shapefile Concepts Overview
• TIGER/Line Shapefile home page
• TIGER/Line Shapefile technical documentation

LA County Samples

Countywide	CSU LA
Census Blocks 2010	Zoomed at CSULA

What is unique about LA County’s data?

1. It is clipped to the ocean boundary. Raw Census data includes a 3 mile buffer into the ocean, which impacts cartography.
2. Each census blocks are assigned with the community name based on the 2011 redistricting unit community names.
3. IMPORTANT! It has been updated to re-include Census Tract 1370.00, which the Census Bureau mistakenly merged with tract 8002.04. Note – until the Census Bureau releases updated population files this update will impact population mapping since population tables will not have 13700.00 (it’s population will be part of 8002.04 showing higher numbers than reality). Please see this post on the County Enterprise GIS about this. We have included the raw file for those who want to use it.

Maps showing what changed

General Area	Zoomed in

How was this data created?

This data was downloaded from Census Bureau website: ftp://ftp2.census.gov/geo/pvs/tiger2010st/06_California/06037/ and clipped to the County Boundary using ESRI’s ArcGIS Desktop. A new field “COMMNAME” was added and populated with city and community names based on 2011 redistricting unit community names in the census block data. This dataset has unique identifier field “GEOID10” for each record, and the census tract and census block number combined field “CTCB10”, block group field “BG10” and census block number field “CB10”.

Download/Access the data

• 2010 Census Blocks.lyr (ArcGIS 10 layer file)- for LA County staff with access to the GIS Repository
• LA County updated Block File – cb2010.shp (zipped shapefile)
• 2010 Census Blocks (zipped original tiger shapefile) – CB2010_Tiger - this is the original file before the changes to Tracts 8002.04 and 1370.00

The Census Bureau (http://www.census.gov/) maintains geographic boundaries for the analysis and mapping of demographic information across the United States. Every 10 years the Census Bureau counts the population of the United States as mandated by Constitution. The Census Bureau releases the results of this county as demographic data with geographic [...]]]> Census Geography Background

The Census Bureau (http://www.census.gov/) maintains geographic boundaries for the analysis and mapping of demographic information across the United States.  Every 10 years the Census Bureau counts the population of the United States as mandated by Constitution.  The Census Bureau releases the results of this county as demographic data with geographic identifiers so that maps and analysis can be performed on the US population.

For a quick introduction to Census geography, click the thumbnail on the right which shows the relationship between Census Blocks, Block Groups, Tracts, and Counties.

For detailed information about the Census Geography, here are some other links:

• Geographic Shapefile Concepts Overview
• TIGER/Line Shapefile home page
• TIGER/Line Shapefile technical documentation

LA County Samples

Countywide	Downtown
Census Tracts 2010	Zoomed at Downtown LA

What is unique about LA County’s data?

1. It  is clipped to the ocean boundary.  Raw Census data includes a 3 mile buffer into the ocean, which impacts cartography.
2. IMPORTANT! It has been updated to re-include Census Tract 1370.00, which the Census Bureau mistakenly merged with tract 8002.04.  Note – until the Census Bureau releases updated population files this update will impact population mapping since population tables will not have 13700.00 (it’s population will be part of 8002.04 showing higher numbers than reality). Please see this post on the County Enterprise GIS about this.  We have included the raw file for those who want to use it.

Maps showing what changed

General Area	Zoomed in

How was this data created?

This data was downloaded from Census Bureau website: http://www.census.gov/cgi-bin/geo/shapefiles2010/file-download and clipped to the County Boundary using  ESRI’s ArcGIS Desktop.  Two new fields were added in census tract data – area in square feet and area in square miles. This dataset has unique identifier field “GEOID10” for each record and the census tract number fields “CT10” and “LABEL” (6-digit number and 6-digit number with decimal point, respectively).

Download/Access the data

• 2010 Census Tracts.lyr (ArcMap 10 Layer File) – for LA County staff with access to the GIS Repository
  
• LA County updated Tract File – ct2010.shp (zipped shapefile)
• Original 2010 Census Tract File – ct2010_original.shp (zipped shapefile) – this is the original file before the changes to Tract 8002.04 and 1370.00

Their primary GIS data download page is here: http://wireless.fcc.gov/geographic/index.htm?job=licensing_database_extracts

To download LA County Data

The LA County extract of this data is part of the Locations/Points of Interest dataset that is available for download from this site. Note – [...]]]> The FCC makes a number of datasets available that cover the various communications data out there.

Their primary GIS data download page is here: http://wireless.fcc.gov/geographic/index.htm?job=licensing_database_extracts

To download LA County Data

The LA County extract of this data is part of the Locations/Points of Interest dataset that is available for download from this site.  Note – as of June 20th, I am verifying LA County’s permission to provide this data as part of the Location Management System download.

Here is a more comprehensive listing of resources provided by the FCC Geographic Information Officer (Michael Byrne).  Thank you Mike for making this data available to us.

Contact

The WTB Mobility Division handles CMRS (Commercial Mobile Radio Service): http://wireless.fcc.gov/index.htm?job=md

Data

WTB raw licensing database tables and documentation can be found here: http://wireless.fcc.gov/uls/index.htm?job=transaction&page=weekly

From these tables, licensed tower location GIS ready data can be created with minimal effort.  I also post this conversion on a non-routine basis for the FCC Mapping CDROM (for the FCC Booth Display).  The data and CDROM can be downloaded from here:

• general info for CDROM – http://wireless.fcc.gov/geographic/index.htm?job=home
• data – http://wireless.fcc.gov/geographic/index.htm?job=licensing_database_extracts

NOTES

Also, any correspondence concerning tower location should mention that the FCC collects licensing data according to the specific rules for each service. In the case of Cellular / PCS, the Commission does not require that they provide technical details for every tower within their network.  Details on what towers they must submit data for can be found here:

http://wireless.fcc.gov/services/index.htm?job=wtb_services_home

Some cool things you can find:

Link to their sensors: http://www.ngdc.noaa.gov/dmsp/sensors.html

The DMSP satellites “see” such environmental features as [...]]]> Defense Meteorological Satellite Program (DMSP), low, earth-orbiting satellites have provided the military with important environmental information.

Some cool things you can find:

1. Nighttime lights of the world – - here’s a KMZ file I downloaded: DMSP_Nighttime_Lights.kmz
2. Visible and Infrared imagery

Link to their sensors: http://www.ngdc.noaa.gov/dmsp/sensors.html

The DMSP satellites “see” such environmental features as clouds, bodies of water, snow, fire, and pollution in the visual and infrared spectra. Scanning radiometers record information which can help determine cloud type and height, land and surface water temperatures, water currents, ocean surface features, ice, and snow. Communicated to ground-based terminals, the data is processed, interpreted by meteorologists, and ultimately used in planning and conducting U.S. military operations worldwide.

There are a number of open map services available here:  I haven’t been able to get them to work yet.

http://www.ngdc.noaa.gov/dmsp/maps.html

For other satellite feeds check this website: http://www.oso.noaa.gov/

This dataset was downloaded, extracted and prepared from the National Hydrography Dataset. The NHD is a comprehensive effort by the US Geological Survey to manage and maintain a comprehensive, high quality, nationwide dataset for GIS mapping and analysis of water features and [...]]]> This dataset contains watershed boundaries for watersheds covering Los Angeles County.

This dataset was downloaded, extracted and prepared from the National Hydrography Dataset.  The NHD is a comprehensive effort by the US Geological Survey to manage and maintain a comprehensive, high quality, nationwide dataset for GIS mapping and analysis of water features and conveyance.  While it is not perfect, and you may find a number of errors, LA County applauds this effort, and is determined to support the enhancement and maintenance of this valuable information since it supports our long-term goal of public, authoritative data.  We are currently investigating the feasibility of stewarding the NHD data for the LA County region.

A description of the NHD from the USGS site:

The National Hydrography Dataset (NHD) is the surface water component of The National Map. The NHD is a digital vector dataset used by geographic information systems (GIS). It contains features such as lakes, ponds, streams, rivers, canals, dams and streamgages. These data are designed to be used in general mapping and in the analysis of surface-water systems.

Samples

Please note that the symbology on the attached maps (and the layers within the downloads) are those developed by the County in order to highlight various hydrographic features.  They are not final in any way.  These sample images contain symbology for all of the NHD layers, since we are making the data available as a single download.

Click a thumbnail to expand
Legend	Countywide	Mid-zoom	Zoomed
Watersheds	Watershed(2)

Processing steps

This data was downloaded from the NHD Data Viewer portal: http://viewer.nationalmap.gov/viewer/nhd.html?p=nhd.

1. I selected the data covering the County of Los Angeles and retrieved the data in personal geodatabase format (I have link to download that file below).
2. To prepare the shapefiles that are available for download, I have joined the features to their descriptions in the NHDFCODE table through the FCODE field and exported them, since a direct export from the geodatabase will not include the related information.  To ensure consistency, I have not deleted any fields that have been created through this join.
3. Symbols were created using the Description Field.

Data Downloads

Each of the datasets below contain the following data:

• Download the raw dataset extracted from the USGS NHD site: lacounty_nhd_data_raw.zip (zipped personal geodatabase) – 10 MB
• Download the extracted dataset as created by LA County: lacounty_nhd_data_extracted.zip (zipped shapefiles, layer files, and .mxd file) – 18 MB

The extracted file includes the following shapefiles:

• Hydro Points – nhd_points_withcodes.shp
• Hydro Lines - nhd_flowline_withcodes.shp
• Hydro Polygons - nhd_waterbody_withcodes.shp
• Watershed Boundaries (Levels 8,10, & 12)

It also includes a number of ArcMap 10 layer files that reference the data, and an ArcMap 10 .mxd file as well.

This dataset was downloaded, extracted and prepared from the National Hydrography Dataset. The NHD is a comprehensive effort by the US Geological Survey to manage and maintain a comprehensive, high quality, nationwide dataset [...]]]> This dataset contains hydologic points (gaging stations, gates, rock features, springs, water intakes, wells, waterfalls, reservoir points) in LA County.

This dataset was downloaded, extracted and prepared from the National Hydrography Dataset.  The NHD is a comprehensive effort by the US Geological Survey to manage and maintain a comprehensive, high quality, nationwide dataset for GIS mapping and analysis of water features and conveyance.  While it is not perfect, and you may find a number of errors, LA County applauds this effort, and is determined to support the enhancement and maintenance of this valuable information since it supports our long-term goal of public, authoritative data.  We are currently investigating the feasibility of stewarding the NHD data for the LA County region.

A description of the NHD from the USGS site:

The National Hydrography Dataset (NHD) is the surface water component of The National Map. The NHD is a digital vector dataset used by geographic information systems (GIS). It contains features such as lakes, ponds, streams, rivers, canals, dams and streamgages. These data are designed to be used in general mapping and in the analysis of surface-water systems.

Samples

Please note that the symbology on the attached maps (and the layers within the downloads) are those developed by the County in order to highlight various hydrographic features.  They are not final in any way.  These sample images contain symbology for all of the NHD layers, since we are making the data available as a single download.

Click a thumbnail to expand
Legend	Countywide	Mid-zoom	Zoomed
Watersheds	Watershed(2)

Processing steps

This data was downloaded from the NHD Data Viewer portal: http://viewer.nationalmap.gov/viewer/nhd.html?p=nhd.

1. I selected the data covering the County of Los Angeles and retrieved the data in personal geodatabase format (I have link to download that file below).
2. To prepare the shapefiles that are available for download, I have joined the features to their descriptions in the NHDFCODE table through the FCODE field and exported them, since a direct export from the geodatabase will not include the related information.  To ensure consistency, I have not deleted any fields that have been created through this join.
3. Symbols were created using the Description Field.

Data Downloads

Each of the datasets below contain the following data:

• Download the raw dataset extracted from the USGS NHD site: lacounty_nhd_data_raw.zip (zipped personal geodatabase) – 10 MB
• Download the extracted dataset as created by LA County: lacounty_nhd_data_extracted.zip (zipped shapefiles, layer files, and .mxd file) – 18 MB

The extracted file includes the following shapefiles:

• Hydro Points – nhd_points_withcodes.shp
• Hydro Lines - nhd_flowline_withcodes.shp
• Hydro Polygons - nhd_waterbody_withcodes.shp
• Watershed Boundaries (Levels 8,10, & 12)

It also includes a number of ArcMap 10 layer files that reference the data, and an ArcMap 10 .mxd file as well.

This dataset was downloaded, extracted and prepared from the National Hydrography Dataset. The NHD is a comprehensive effort by the US Geological Survey to manage and maintain a comprehensive, high quality, nationwide dataset for GIS mapping and analysis of water features and conveyance. While [...]]]> This dataset contains lakes & reservoirs in LA County.

This dataset was downloaded, extracted and prepared from the National Hydrography Dataset.  The NHD is a comprehensive effort by the US Geological Survey to manage and maintain a comprehensive, high quality, nationwide dataset for GIS mapping and analysis of water features and conveyance.  While it is not perfect, and you may find a number of errors, LA County applauds this effort, and is determined to support the enhancement and maintenance of this valuable information since it supports our long-term goal of public, authoritative data.  We are currently investigating the feasibility of stewarding the NHD data for the LA County region.

A description of the NHD from the USGS site:

The National Hydrography Dataset (NHD) is the surface water component of The National Map. The NHD is a digital vector dataset used by geographic information systems (GIS). It contains features such as lakes, ponds, streams, rivers, canals, dams and streamgages. These data are designed to be used in general mapping and in the analysis of surface-water systems.

Samples

Please note that the symbology on the attached maps (and the layers within the downloads) are those developed by the County in order to highlight various hydrographic features.  They are not final in any way.  These sample images contain symbology for all of the NHD layers, since we are making the data available as a single download.

Click a thumbnail to expand
Legend	Countywide	Mid-zoom	Zoomed
Watersheds	Watershed(2)

Processing steps

This data was downloaded from the NHD Data Viewer portal: http://viewer.nationalmap.gov/viewer/nhd.html?p=nhd.

1. I selected the data covering the County of Los Angeles and retrieved the data in personal geodatabase format (I have link to download that file below).
2. To prepare the shapefiles that are available for download, I have joined the features to their descriptions in the NHDFCODE table through the FCODE field and exported them, since a direct export from the geodatabase will not include the related information.  To ensure consistency, I have not deleted any fields that have been created through this join.
3. Symbols were created using the Description Field.

Data Downloads

Each of the datasets below contain the following data:

• Download the raw dataset extracted from the USGS NHD site: lacounty_nhd_data_raw.zip (zipped personal geodatabase) – 10 MB
• Download the extracted dataset as created by LA County: lacounty_nhd_data_extracted.zip (zipped shapefiles, layer files, and .mxd file) – 18 MB

The extracted file includes the following shapefiles:

• Hydro Points – nhd_points_withcodes.shp
• Hydro Lines - nhd_flowline_withcodes.shp
• Hydro Polygons - nhd_waterbody_withcodes.shp
• Watershed Boundaries (Levels 8,10, & 12)

It also includes a number of ArcMap 10 layer files that reference the data, and an ArcMap 10 .mxd file as well.

This dataset was downloaded, extracted and prepared from the National Hydrography Dataset. The NHD is a comprehensive effort by the US Geological Survey to manage and maintain a comprehensive, high quality, nationwide dataset for GIS mapping and analysis of water features and [...]]]> This dataset contains rivers, streams, and water conveyance mechanisms (pipelines, aqueducts).

This dataset was downloaded, extracted and prepared from the National Hydrography Dataset.  The NHD is a comprehensive effort by the US Geological Survey to manage and maintain a comprehensive, high quality, nationwide dataset for GIS mapping and analysis of water features and conveyance.  While it is not perfect, and you may find a number of errors, LA County applauds this effort, and is determined to support the enhancement and maintenance of this valuable information since it supports our long-term goal of public, authoritative data.  We are currently investigating the feasibility of stewarding the NHD data for the LA County region.

A description of the NHD from the USGS site:

The National Hydrography Dataset (NHD) is the surface water component of The National Map. The NHD is a digital vector dataset used by geographic information systems (GIS). It contains features such as lakes, ponds, streams, rivers, canals, dams and streamgages. These data are designed to be used in general mapping and in the analysis of surface-water systems.

Samples

Please note that the symbology on the attached maps (and the layers within the downloads) are those developed by the County in order to highlight various hydrographic features.  They are not final in any way.  These sample images contain symbology for all of the NHD layers, since we are making the data available as a single download.

Click a thumbnail to expand
Legend	Countywide	Mid-zoom	Zoomed

Processing steps

This data was downloaded from the NHD Data Viewer portal: http://viewer.nationalmap.gov/viewer/nhd.html?p=nhd.

1. I selected the data covering the County of Los Angeles and retrieved the data in personal geodatabase format (I have link to download that file below).
2. To prepare the shapefiles that are available for download, I have joined the features to their descriptions in the NHDFCODE table through the FCODE field and exported them, since a direct export from the geodatabase will not include the related information.  To ensure consistency, I have not deleted any fields that have been created through this join.
3. Symbols were created using the Description Field.

Data Downloads

Each of the datasets below contain the following data:

• Download the raw dataset extracted from the USGS NHD site: lacounty_nhd_data_raw.zip (zipped personal geodatabase) – 10 MB
• Download the extracted dataset as created by LA County: lacounty_nhd_data_extracted.zip (zipped shapefiles, layer files, and .mxd file) – 18 MB

The extracted file includes the following shapefiles:

• Hydro Points – nhd_points_withcodes.shp
• Hydro Lines - nhd_flowline_withcodes.shp
• Hydro Polygons - nhd_waterbody_withcodes.shp
• Watershed Boundaries (Levels 8,10, & 12)

It also includes a number of ArcMap 10 layer files that reference the data, and an ArcMap 10 .mxd file as well.

Historically this file has had a number of identified issues with its geographic accuracy, but the 2010 file has been tested by LA County and found to be highly accurate [...]]]> The TIGER road file is a street centerline network used by the US Census Bureau to help locate and find citizens during its decennial census.

Historically this file has had a number of identified issues with its geographic accuracy, but the 2010 file has been tested by LA County and found to be highly accurate – accurate enough, in fact, that the County is using this file as a base for a new Countywide address and street network file.

The TIGER roads file was extracted from the Census Redistricting data available from the US Census Bureau’s Redistricting Website.  The source of the data is the TIGER FACES file (tl_2010_06037_faces.shp) which contains all of the lines that make up the Census data.  Information was extracted using the “ROADFLG” field which separates roads from other features like streams.

Full documentation of the TIGER file is available from the Shapefiles Technical Documentation Page.  Road Classification is stored in the MTFCC field – and descriptions of the various types are available from the Appendix F Link there.  Here is a link directly to Appendix F.

Please note – we have determined that the new MTFCC codes (which replace the earlier CFCC codes) do not capture secondary roads (not minor roads, but also not highways).  The County will be fixing this as we move forward.

Download the data

• Zipped shapefile: Tigerroads.zip

Samples

These are very schematic thumbnails.

Here is a link to a download from NREL for alternative fuel stations: http://www.afdc.energy.gov/afdc/data_download/

Data links: