**Status of Framework Layers in Iowa**

**September 2008**

**1) Geodetic Control**

FGDC Description: *Geodetic control provides a common reference system
for establishing the coordinate positions of all geographic data. It
provides the means for tying all geographic features to common,
nationally used horizontal and vertical coordinate systems. The main
features of geodetic control information are geodetic control stations.
These monumented points (or in some cases active Global Positioning
System control stations) have precisely measured horizontal or vertical
locations and are used as a basis for determining the positions of other
points. The geodetic control component of the framework consists of
geodetic control stations and related information \-- the name, feature
identification code, latitude and longitude, orthometric height, and
ellipsoid height, and metadata for each station. The metadata for each
geodetic control point contains descriptive data, positional accuracy,
condition, and other pertinent characteristics for that point. Geodetic
control information plays a crucial role in developing all framework
data and users\' applications data, because it provides the spatial
reference source to register all other spatial data. In addition,
geodetic control information may be used to plan surveys, assess data
quality, plan data collection and conversion, and fit new areas of data
into existing coverages.*

Current status:

1.  There are 6597 (142 HARN) NGS control points in Iowa (retrieved
    summer 2006 from NGS database), 1757 of them having been visited in
    the last 20 years by NGS.

2.  There are 142 HARN control points in Iowa (retrieved summer 2006
    from NGS database)

3.  About 60 counties in Iowa have GPS control surveys. Some are
    available to the public through real estate web mapping applications
    or the ICIT data repository <https://www.iowagisdata.org/>.

4.  There are pdf files containing information on USGS benchmarks, but
    no GIS coverage showing their approximate locations.

Table 1: Description of Geodetic Control layers:

+---------+--------+-----------+--------+---------+--------+---------+
| **Layer | **     | **GIS     | **Inte | **Dist  | *      | **Data  |
| or      | Source | Data      | grated | ributed | *Accur | model/  |
| Su      | or     | Status    | into   | by:**   | acy:** | Data    |
| b-layer | co     | and       | sta    |         |        | stan    |
| name**  | mpiled | update    | tewide |         |        | dard:** |
|         | by:**  | cycle:**  | covera |         |        |         |
|         |        |           | ges:** |         |        |         |
+---------+--------+-----------+--------+---------+--------+---------+
| NGS     | NGS    | Exist     | IGIC   | IGIC    | varies | Point   |
| control |        | s/yearly? | Ge     | server  |        | shape   |
| points  |        |           | odetic | and     |        | file/   |
| for     |        |           | Com    | control |        |         |
| Iowa    |        |           | mittee | point   |        | N       |
|         |        |           |        | web     |        | GS/FGDC |
|         |        |           |        | viewer  |        |         |
+---------+--------+-----------+--------+---------+--------+---------+
| HARN    | NGS    | Exist     | "      | "       | Very   | Point   |
| points  |        | s/unknown |        |         | high - | shape   |
| for     |        |           |        |         | cm     | file/   |
| Iowa    |        |           |        |         |        |         |
|         |        |           |        |         |        | N       |
|         |        |           |        |         |        | GS/FGDC |
+---------+--------+-----------+--------+---------+--------+---------+
| County  | Co     | CPs exist | "      | Point   | Very   | Point   |
| GPS     | unties | for about |        | desc    | high - | shape   |
| control | and    | 66-70     |        | ription | cm     | file/   |
| mo      | contr  | counties; |        | files   |        |         |
| numents | actors | some are  |        | stored  |        | ?       |
|         |        | digital   |        | on      |        |         |
|         |        | /unknown  |        | county  |        |         |
|         |        |           |        | servers |        |         |
+---------+--------+-----------+--------+---------+--------+---------+
| USGS    | Coord  | Does not  | ?      | None    | U      | No      |
| Ben     | inates | exist     |        |         | nknown | known   |
| chmarks | u      |           |        |         |        | GIS     |
|         | nknown |           |        |         |        | c       |
|         |        |           |        |         |        | overage |
+---------+--------+-----------+--------+---------+--------+---------+

**2) Orthoimagery**

FGDC Description: *Orthoimagery provides a positionally correct image of
the earth. An orthoimage is a georeferenced image prepared from an
aerial photograph or other remotely sensed data from which displacements
of images caused by sensor orientation and terrain relief have been
removed. An orthoimage has the same metric properties as a map and has a
uniform scale.* *Digital orthoimages are composed of an array of
georeferenced pixels that encode ground reflectance as a discrete
digital value. Many geographic features, including those that are part
of the framework, can be interpreted and compiled from an orthoimage.
Orthoimages can also serve as a backdrop to reference the results of an
application to the landscape. The framework may include imagery that
varies in resolution from submeter to tens of meters. Accurately
positioned, high-resolution data (pixels of 1 meter or finer) are
presumed to be the most useful for supporting the compilation of
framework features, particularly those that support local data needs. In
some areas, lower-resolution imagery may be sufficient to support the
framework and applications.*

*Orthoimagery provides a useful tool for a variety of applications.
Because many land features can be seen on an orthoimage, it can serve as
a backdrop for visual reference purposes, saving the expense of creating
vector files of features that are needed only for reference.
Orthoimagery can be used to compile vector themes photogrammetrically.*

Current status:

1.  Many county and cities in Iowa contract for different orthoimagery
    mostly 2', 1' and 6" pixel products, in black and white or natural
    color. In rural areas 1"=400' is the usual target accuracy and in
    urban areas, 1"=100'. Some of this imagery is available to the
    public, mostly through county real estate web applications.
    Recently, groups of counties are starting to coordinate regional
    flights to save acquisition costs. Collection of countywide 6" color
    orthos is becoming more common.

2.  IGIC is leading an effort to acquire a statewide, multi-band ortho
    coverage to coincide with the lidar acquisition (2' pixel).
    <http://ortho.gis.iastate.edu/> DNR is working on an RFP for
    completion of this project in 2009 and 2010.

3.  Imagery for the Nation (IFTN) is a National States Geographic
    Information Council (NSGIC) led effort to get the federal government
    to fund consistent, regular orthoimagery acquisitions across the US
    (<http://www.nsgic.org/hottopics/imageryforthenation.cfm>). So far
    no funding has been appropriated for this effort, so if may be
    several years before it produces any data. The 1-meter NAIP orthos
    would be completely federally funded with yearly flights; 1' color
    orthos would be 50% federal and 50% local option on a 3 year cycle
    (otherwise the federal pays 100% every 6 years); and the urban 6"
    color orthos would require 50% local funding (otherwise no
    acquisition without the local involvement).

Table 2: Description of Ortho-imagery Projects (future IFTN products
included for comparison):

+--------+----------+----------+--------+---------+--------+---------+
| **Sub  | **Source | **Data   | **Inte | **Dist  | *      | **Data  |
| -layer | or       | Status   | grated | ributed | *Accur | model/  |
| name** | compiled | and      | into   | by:**   | acy:** | Data    |
|        | by:**    | update   | IGI    |         |        | stan    |
|        |          | cycle:** | covera |         |        | dard:** |
|        |          |          | ges:** |         |        |         |
+--------+----------+----------+--------+---------+--------+---------+
| Sta    | IGIC and | 2007 17  | IGIC   | I       | 1      | DOQQs   |
| tewide | DNR      | counties | and    | GIC/ISU | "=400' | and     |
| 2'     |          | in NW    | DNR    | Ortho   |        | county  |
| pixel, |          | Iowa;    |        | server  | (16'   | mo      |
| 4-band |          | RFP to   |        |         | or 5   | saics/? |
| ortho  |          | be       |        |         | m      |         |
|        |          | released |        |         | eters) |         |
|        |          | in 2008  |        |         |        |         |
|        |          | for      |        |         |        |         |
|        |          | rest/    |        |         |        |         |
|        |          | one-time |        |         |        |         |
|        |          | over 3   |        |         |        |         |
|        |          | years.   |        |         |        |         |
+--------+----------+----------+--------+---------+--------+---------+
| IFTN   | U        | Futur    | IGI    | IGI     | 1:     | DOQQs   |
| NAIP   | SGS/USDA | e/Yearly | s      | server  | 12,000 | and     |
| 1      |          |          | ervice |         |        | county  |
| -meter |          |          | bureau |         | topo   | mo      |
| color  |          |          |        |         | scale  | saics/? |
| ortho, |          |          |        |         |        |         |
| l      |          |          |        |         | (38'   |         |
| eaf-on |          |          |        |         | or 12  |         |
|        |          |          |        |         | m      |         |
|        |          |          |        |         | eters) |         |
+--------+----------+----------+--------+---------+--------+---------+
| IFTN   | USGS     | Future/3 | IGI    | IGI     | \>1    | ??      |
| 1'     |          | year     | s      | server  | "=100' | tiles   |
| color  |          | cycle    | ervice |         |        | and     |
| --     |          |          | bureau |         | (5' or | county  |
| leaf   |          |          |        |         | 1.5    | mo      |
| off;   |          |          |        |         | m      | saics/? |
| all    |          |          |        |         | eters) |         |
| co     |          |          |        |         |        |         |
| unties |          |          |        |         |        |         |
+--------+----------+----------+--------+---------+--------+---------+
| IFTN   | USGS     | Future/3 | IGI    | IGI     | \<1    | ??      |
| 6"     |          | year     | s      | server  | "=100' | tiles   |
| color  |          | cycle    | ervice |         |        | and     |
| --     |          |          | bureau |         | (2.5'  | city    |
| leaf   |          |          |        |         | or .76 | mo      |
| off,   |          |          |        |         | meter) | saics/? |
| census |          |          |        |         |        |         |
| urban  |          |          |        |         |        |         |
| areas  |          |          |        |         |        |         |
+--------+----------+----------+--------+---------+--------+---------+

**3) Administrative Boundaries (Governmental Units)**

FGDC description of Governmental Units:

*The framework includes the geographic areas of units of government.
These units include:*

*the nation,*

*states and statistically equivalent areas,*

*counties and statistically equivalent areas,*

*incorporated places and consolidated cities,*

*functioning and legal minor civil divisions,*

*federal- or state-recognized American Indian reservations and
trustlands, and*

*Alaska Native regional corporations.*

*Each of these features includes the attributes of name and the
applicable Federal Information Processing Standard (FIPS) code. Features
boundaries include information about other features (such as roads,
railroads, or streams) with which the boundaries are associated and a
description of the association (such as coincidence, offset, or
corridor). Governmental unit boundaries are used for a wide variety of
applications. Some need the boundaries only for information and
orientation; others require the polygons to determine inclusion related
to a number of other features. Business GIS is a very active field that
uses these boundaries for statistical analysis and decision making.*

Current status:

1.  Iowa DNR has a coverage of counties and the state outline that was
    digitized from USGS 24k topographic maps over 25 years ago.
    <ftp://ftp.igsb.uiowa.edu/GIS_library/IA_State/Admin_Political_Boundary/>

2.  City boundary coverages are available from the Iowa DOT
    <http://gis.iowadot.gov/downloads/zipped_files/Boundaries/>

3.  US Census Bureau has TIGER line files now as shape files. These will
    continue to be updated up until the 2010 census.
    <ftp://ftp2.census.gov/geo/tiger/TIGER2007FE/19_IOWA/>

4.  The most accurate boundary data is maintained by city and county GIS
    programs (about 75 counties -- see Figure 1), but none are currently
    integrated into a statewide coverage. Some are available to the
    public through real estate web mapping applications or the ICIT data
    repository <https://www.iowagisdata.org/> .

Table 3: Description of Administrative Boundary Layers:

  ------------- ------------ ---------------- -------------- --------------- --------------- -------------
  **Sub-layer   **Source or  **GIS Status and **Integrated   **Distributed   **Accuracy:**   **Data model/
  name**        compiled     update cycle:**  into statewide by:**                           Data
                by:**                         coverages:**                                   standard:**

  State         USGS topo    Exists/none      DNR/IGS        NRGIS server    USGS 24k topo   Polygon shape
  boundary      maps -                                                       maps: \~12      file/?
                compiled                                                     meters          
                from county                                                                  
                boundaries                                                                   

  County        USGS topo    Exists/none      "              "               USGS 24k topo   Polygon shape
  boundaries    maps -                                                       maps: \~12      file/?
                compiled                                                     meters          
                from county                                                                  
                boundaries                                                                   

  City          1990 and     Exists/decadal   "              "               unknown         Polygon shape
  boundaries    2000 Census                                                                  file/?
                Tiger/Line                                                                   
                files                                                                        

  Political     1990 Census  Exists/none      "              "               unknown         Polygon shape
  townships     Tiger/Line                                                                   file/?
                files                                                                        

  City          City and     Available for    Future IGI     Future IGI      1" = 100'       Polygon shape
  boundaries    county GIS   some counties    service bureau server                          file/?
                programs     from ICIT data                                                  
                             repository                                                      
  ------------- ------------ ---------------- -------------- --------------- --------------- -------------

Figure 1. Shows the status of county GIS programs in Iowa. Counties in
green will

likely have most framework layers, while counties in red and yellow will
not (except for some county E911 systems may have roads and addresses).

![](media/image1.wmf){width="6.875in" height="5.074305555555555in"}

**4) Cadastral**

FGDC Description: *Cadastral information refers to property interests.
Cadastral data represent the geographic extent of the past, current, and
future rights and interests in real property. The spatial information
necessary to describe the geographic extent and the rights and interests
includes surveys, legal description reference systems, and
parcel-by-parcel surveys and descriptions. Cadastral information
included in the framework:*

-   *cadastral reference systems, such as the Public Land Survey System
    (PLSS) and similar systems for areas not covered by the PLSS (for
    example, the Connecticut Western Reserve in Ohio), and*

-   *Parcels, including publicly administered parcels, such as military
    reservations, national forests, and state parks*

*Features include the survey corner, survey boundary, and parcel. Each
instance of a feature has the attributes of name (or other common
identifier) and information about data quality. Each instance also
should have a permanent feature identification code. For the PLSS, the
minimum content is the boundaries of sections, including deflection
points and the positions for quarter corners along section boundaries.
Boundaries that have been surveyed are the preferred content for
cadastral reference systems. Cadastral information is the basis of many
analysis, decision-making, and operational applications, such as site
selection, land use administration, and transportation planning. The
reference system can be used to register locally produced information
into the framework. Information about publicly owned lands serves both
those who administer the lands and those who have interests in them.
Framework representation of these lands provides useful information
about their location, boundaries, extent, and relationships to other
geographic features and phenomena. Because parcels play an important
role in many public and private sector activities, and parcel
information is a basic ingredient of many applications, there is
interest in providing multiple levels of cadastral data. These levels
would be based on available data and customer requirements. The
framework provides a means to link existing parcel data into the larger
cadastral network.*

Current status:

1.  Iowa DNR has a GIS shape file coverage of the PLSS sections and
    townships that was digitized from USGS 24k topographic maps almost
    20 year ago.
    <ftp://ftp.igsb.uiowa.edu/GIS_library/IA_State/Geographic/>

2.  IDOT recently re-digitized the PLSS boundaries.
    <http://gis.iowadot.gov/downloads/zipped_files/Boundaries/>

3.  The most accurate PLSS and parcel boundary data is maintained by
    city and county GIS programs (about 75 counties -- see Figure 1),
    but none are currently integrated into a statewide coverage. Some
    are available to the public through real estate web mapping
    applications or the ICIT data repository
    <https://www.iowagisdata.org/> .

Table 4: Description of Cadastral Layers:

  ------------- ---------- ----------------- -------------- --------------- --------------- -------------
  **Sub-layer   **Source   **GIS status and  **Integrated   **Distributed   **Accuracy:**   **Data model/
  name**        or         update cycle:**   into IGI       by:**                           Data
                compiled                     coverages:**                                   standard:**
                by:**                                                                       

  PLSS sections Compiled   Exists/none       DNR/IGS        NRGIS server    \~ 12 meters    Polygon shape
  and townships from USGS                                                                   file/?
                24k topo                                                                    
                maps                                                                        

  PLSS corners  "          Exists/none       "              "               \~ 12 meters    point shape
                                                                                            file/?

  Parcel        County and Exists in digital Future IGI     Future IGI      1"=400' in      Polygon shape
  boundaries    City GIS   form for about 75 service bureau server          rural areas;    file/?
  and right of             counties/yearly                                  1"=100' in      
  way                                                                       cities          
  ------------- ---------- ----------------- -------------- --------------- --------------- -------------

Issues and questions: PLSS corners and certificates could be made
available through a web application similar to the Geodetic Control
Monument viewer.

**5) Transportation**

FGDC description: *The framework\'s transportation data include the
following major common features of transportation networks and
facilities:*

-   *roads \-- centerlines, feature identification code (using linear
    referencing systems where available), functional class, name
    (including route numbers), and street address ranges;*

-   *trails \-- centerlines, feature identification code (using linear
    referencing systems where available), name, and type;*

-   *railroads \-- centerlines, feature identification code (using
    linear referencing systems where available), and type;*

-   *waterways \-- centerlines, feature identification code (using
    linear referencing systems where available), and name;*

-   *airports and ports \-- feature identification code and name; and*

-   *bridges and tunnels \-- feature identification code and name.*

*Transportation information is used in many applications. Some use it
only for reference purposes, as an element of base mapping, while many
others use it to attach other types of information, such as
address-related information or street characteristics. Transportation
features and related data are important elements of many planning
applications. Geocoding applications use road and related address data
for uses ranging from marketing analysis to site identification.*
*Routing applications use street network data for operations such as
vehicle dispatch and fleet management.*

Current status:

1.  IDOT has available road centerlines and other layers from its GEMS
    system for each county and statewide. They have 28E agreements with
    28 counties to update the road centerlines with local GIS info.
    Otherwise the GEMS road centerlines are digitized from the 1:12,000
    CIR and NAIP DOQQs.

-   Roads: <http://gis.iowadot.gov/downloads/zipped_files/GIMS_History/>

-   Trails:
    <http://gis.iowadot.gov/downloads/zipped_files/miscBoundaries/2006/TRAILS_SO_2006.zip>

-   Rails:
    <http://gis.iowadot.gov/downloads/zipped_files/rail/2002/RAILROADS.zip>

-   Waterways: <http://www.iwr.usace.army.mil/ndc/db/waternet/data/> Not
    sure if there's a place to get this in GIS format already

-   Aviation: <http://gis.iowadot.gov/downloads/zipped_files/Aviation/>

-   Bridges and tunnels:
    <http://gis.iowadot.gov/downloads/zipped_files/GIMS_History/>

2.  IDOT Linear Referencing System transportation data will be available
    in 2009 from DOT and through CAP Infrastructure project

3.  US Census Bureau Tiger/Line and Tiger Shape Files available at
    <ftp://ftp2.census.gov/geo/tiger/TIGER2007FE/19_IOWA/>

4.  Some counties and cities maintain their own road centerlines. Some
    are available to the public through real estate web mapping
    applications or the ICIT data repository
    <https://www.iowagisdata.org/> .

Table 5: Description of Transportation sub-layers:

  ------------- ------------ ---------- -------------- --------------- --------------- -------------
  **Sub-layer   **Source or  **Update   **Integrated   **Distributed   **Accuracy:**   **Data model/
  name**        compiled     cycle:**   into IGI       by:**                           Data
                by:**                   coverages:**                                   standard:**

  Road          IDOT; with   Yearly?    IDOT           IDOT server or  5-10 meters     line shape
  centerlines   some county                            IGI server                      file/?
                road                                                                   
                centerline                                                             
                files                                                                  

  trails        County and   ?          "              "               ?               line shape
                city GIS,                                                              file/?
                COGS, DNR,                                                             
                DOT                                                                    

  railroads     County and   ?          "              "               ?               line shape
                City GIS;                                                              file/?
                Federal                                                                
                Highway                                                                
                Admin                                                                  

  waterways     US COE       ?          unknown        "               ?               line or point
                                                                                       shape file

  airports and  IDOT         ?          IDOT           "               ?               Point shape
  ports                                                                                files/?

  bridges and   IDOT         ?          IDOT           "               ?               Point or line
  tunnels                                                                              shape files/?
  ------------- ------------ ---------- -------------- --------------- --------------- -------------

**6) Elevation**

FGDC Description: *Elevation data provide information about terrain.
Elevation refers to a spatially referenced vertical position above or
below a datum surface. The framework includes the elevations of land
surfaces and the depths below water surfaces (bathymetry). For land
surfaces, the framework employs an elevation matrix. Elevation values
will be collected at a post-spacing of 2 arc-seconds (approximately 47.4
meters at 40° latitude) or finer. In areas of low relief, a spacing of
1/2 arc-second (approximately 11.8 meters at 40° latitude) or finer will
be sought.*

*For depths, the framework consists of soundings and a gridded bottom
model. Water depth is determined relative to a specific vertical
reference surface, usually derived from tidal observations. In the
future, this vertical reference may be based on a global model of the
geoid or the ellipsoid, which is the reference for expressing height
measurements in the Global Positioning System.*

*Elevation data are used in many different applications. Users may want
a representation of the terrain, such as a contour map, spot elevations,
or a three-dimensional perspective view. Elevation data are also used to
build models and perform applications, ranging from line-of-sight
calculations, to road planning, to water runoff. Elevation data are
often combined with other data themes in applications and mapping.*

Current status:

1.  USGS has available the ubiquitous 10 and 30 meter National Elevation
    Data (NED) DEMs for the US derived from the 24k topo contours. Iowa
    DNR has these available in statewide ESRI grid files for download:
    <ftp://ftp.igsb.uiowa.edu/GIS_library/IA_State/Elevation/NED/>

2.  State has a lidar program that is collecting 1.4 meter postings
    statewide, with 18cm RMSE vertical accuracy in bare areas, 37 cm in
    vegetated areas. DNR is working to produce 1 meter DEMs, shaded
    relief and intensity images, and 2' contours from the lidar data.
    ASCII and LAS files for raw 2x2km tiles are available from UNI
    Geotree site: <http://www.geotree.uni.edu/LidarProject.aspx>

Table 6: Description of Elevation sub-layers:

+-----------+-------+---------+--------+---------+--------+----------+
| **        | **So  | **GIS   | **Inte | **Dist  | *      | **Data   |
| Sub-layer | urce/ | Data    | grated | ributed | *Accur | model/   |
| name**    | com   | Status  | into   | by:**   | acy:** | Data     |
|           | piled | Update  | IGI    |         |        | sta      |
|           | by:** | c       | covera |         |        | ndard:** |
|           |       | ycle:** | ges:** |         |        |          |
+-----------+-------+---------+--------+---------+--------+----------+
| High-r    | Stat  | Cu      | DNR    | DNR,    | Hor. 1 | ??       |
| esolution | ewide | rrently |        | ISU and | meter  | tiles/   |
| DEM       | 1.4   | about   |        | UNI     |        | county   |
| (1-meter  | meter | 22% of  |        | servers | Ver.   | mosaics  |
| grid      | bare  | state   |        |         | 18 cm  | and      |
| spacing,  | earth | av      |        |         | bare;  | HUC-12   |
| elevation | l     | ailable |        |         | 37 cm  | wa       |
| in        | idar/ | for     |        |         | veg    | tersheds |
| meters)   | DNR   | d       |        |         | etated |          |
|           |       | ownload |        |         |        |          |
|           |       | as      |        |         |        |          |
|           |       | ind     |        |         |        |          |
|           |       | ividual |        |         |        |          |
|           |       | til     |        |         |        |          |
|           |       | es/None |        |         |        |          |
+-----------+-------+---------+--------+---------+--------+----------+
|           |       |         |        |         |        |          |
+-----------+-------+---------+--------+---------+--------+----------+
| 2'        | Stat  | Futu    | DNR    | DNR or  | "      | Line     |
| contours  | ewide | re/None |        | UNI     |        | shape    |
|           | 1.4   |         |        |         |        | files/?  |
|           | meter |         |        |         |        |          |
|           | bare  |         |        |         |        |          |
|           | earth |         |        |         |        |          |
|           | l     |         |        |         |        |          |
|           | idar/ |         |        |         |        |          |
|           | DNR   |         |        |         |        |          |
+-----------+-------+---------+--------+---------+--------+----------+

**7) Hydrography**

FGDC description: *Framework hydrography data include surface water
features such as lakes and ponds, streams and rivers, canals, oceans,
and shorelines. Each of these features has the attributes of a name and
feature identification code. Centerlines and polygons encode the
positions of these features. For feature identification code, many
federal and state agencies use the Reach scheme developed by the U.S.
Environmental Protection Agency. Many hydrography data users need
complete information about connectivity of the hydrography network and
the direction in which the water flows encoded in the data. To meet
these needs, additional elements representing the flow of water and
connections between features may be included in framework data.*

*A shoreline is the intersection of the water\'s surface with land. It
usually is referenced to some analytically determined stage of the tide
for coastal water, or other water level for lakes and rivers. Several
shorelines, referenced to different stages of the water such as \"mean
high water\" and \"mean lower low water,\" are included in the
framework. These shorelines are included because different users require
different shorelines and the complex, nonlinear relationships between
various shorelines make it difficult to determine them analytically.
Attributes include the description of the tidal reference for the
shoreline.*

*Hydrography is important to many applications. As with other data
themes, many users need hydrographic features as reference or base map
data. Other applications, particularly environmentally oriented
analyses, need the information for analysis and modeling of water
supply, pollution, flood hazard, wildlife, development, and land
suitability.*

Current situation:

1.  USGS has produced 1:24,000 scale National Hydrography Dataset for
    Iowa and is available here: <http://nhd.usgs.gov/data.html> This
    data is subdivided by watershed. It is based on the USGS 7.5'
    Topographic maps, which vary in age from the 1950s to the 1990s in
    Iowa.

2.  Iowa DNR and USGS are partnering to develop a local resolution NHD
    dataset for Iowa, extracting line work from the statewide lidar
    data, and conflating 24k NHD attributes and updated National
    Wetlands Inventory attributes. The pilot includes 27 HUC-12s, out of
    about 1700 watersheds covering the state.

Table 7: Description of Hydrography sub-layers:

  ------------- ----------- ----------------- -------------- --------------- --------------- ----------------
  **Sub-layer   **Source/   **GIS data        **Integrated   **Distributed   **Accuracy:**   **Data model/
  name**        compiled    status/update     into IGI       by:**                           Data standard:**
                by:**       cycle:**          coverages:**                                   

  River and     Iowa DNR    Pilot for 27      DNR            DNR             At least        Line shape
  stream        and USGS    HUC-12s/unknown                                  1"=400' in      files/ArcHydro
  centerlines                                                                rural areas     and NHD

  Water bodies  "           "                 "              "               "               Polygon shape
                                                                                             files/ArcHydro
                                                                                             and NHD

  Watershed     Lidar       Future/none       "              "               "               "
  boundaries    DEMs/DNR                                                                     
  (12-digit                                                                                  
  HUC)                                                                                       

                                                                                             

                                                                                             

                                                                                             
  ------------- ----------- ----------------- -------------- --------------- --------------- ----------------

**8) Address Points**

There is apparently no federal standard for address points. Many states
and counties have address point GIS data, but there doesn't appear to be
many standards documents. There is a USGS National Map best practice
data model for structures that has a point layer, but this best practice
model is not the same as a formal data content standard.
(<http://bpgeo.cr.usgs.gov/model/acrodocs/Poster_BPStructures_03_01_2006.pdf>
)

Current Status:

1.  A few counties are known to have an address point data layers but
    none of the GIS layers are publicly available at this time. Some
    counties also have point address files for the E911 systems, but
    again these are not publicly available nor the extent of use well
    known.

2.  Iowa DNR in conjunction with other state agencies has submitted a
    proposal to the state's Pooled Technology Fund for a project to
    create an address point file for 30-50 counties to be used in a
    geocoding web application. If funding is approved by the state
    legislature in the spring of 2009, work could begin next July. A
    second project proposal will be prepared to finish the state in
    subsequent years.

**9) Structures**

There is apparently no federal data standard for structures but there is
a USGS National Map best practice data model for structures,
(<http://bpgeo.cr.usgs.gov/model/acrodocs/Poster_BPStructures_03_01_2006.pdf>
). Beyond this, there is little documentation for this basic framework
layer.

Current Status:

1.  A few counties are known to have building footprint and other
    structures (bridges, tunnels, cell towers, etc.) as part of their
    county GIS programs. The extent of this type of coverage is unknown
    at this time.

2.  The Iowa Geographic Information Council has received a FGDC CAP
    Grant, Category 5 Structures and Transportation Stewardship,
    in 2008. Iowa State University is using funding from the grant to
    enhance the Iowa Geographic Map Server to include additional space
    for new ortho-imagery to serve as background data for a structure
    web update tool, which will be using ArcGIS server technology to
    allow updates to a centralized statewide database of structures
    (building footprints) derived from the lidar data. The web tool is
    being tested with structures data for Polk County, which was flown
    in 2006 with lidar data for the National Governor's Conference, and
    building footprints were extracted. Building footprints will be
    extracted from the state's lidar program as more lidar data is
    processed by DNR.

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+--------------+--------------+-----------------+----------+----------+
| **LEGEND**   |              |                 |          |          |
+--------------+--------------+-----------------+----------+----------+
| SCALE        |              | NSSDA           | Pixel    | Pixel    |
|              |              | Horizontal      | size     | size     |
|              |              | Accuracy (95%)  |          |          |
|              |              |                 | in feet  | In       |
|              |              |                 |          | meters   |
+--------------+--------------+-----------------+----------+----------+
| statew       |              | 190+ feet (60+  |          | 10-30 m  |
| ide-regional |              | meters)         |          |          |
| 1:100,000+   |              |                 |          |          |
+--------------+--------------+-----------------+----------+----------+
| quadran      |              | 38 - 46 feet    |          | 1-5 m    |
| gle-regional |              | (12-14 meters)  |          |          |
| 1:12,        |              |                 |          |          |
| 000-1:24,000 |              |                 |          |          |
+--------------+--------------+-----------------+----------+----------+
| county       |              | 16 feet (5      | 2\'      |  .61 m   |
| 1\"=400\'    |              | meters)         |          |          |
+--------------+--------------+-----------------+----------+----------+
| city         |              | 4 feet (1.2     | 6\"-1\'  |  .15-.3  |
| 1\"=100\'    |              | meters)         |          | m        |
+--------------+--------------+-----------------+----------+----------+
| site         |              | 2 feet (.6      | 3\"-6\"  |  .08-.15 |
| 1\"=50\'     |              | meters)         |          | m        |
+--------------+--------------+-----------------+----------+----------+
| Survey-grade |              | cm accuracy     |          |          |
| GPS          |              |                 |          |          |
+--------------+--------------+-----------------+----------+----------+