This is a follow up to my recent post on the addition of lands formerly held by the McGregor Correctional facility to Moreau Lake State Park. That post included a map image with a rough outline of the newly added parcel. I've refined that boundary and saved it to a KMZ format file that can be opened in Google Earth/Maps.
Link to the Moreau Lake State Park Boundary File
https://drive.google.com/file/d/0B3QHBL0PwDqWZFpxSG9nYU1BY0E/view?usp=sharing
Clicking the link will open a new browser window (or tab) showing Google Maps with the boundary layer displayed as an overlay. You can also download the boundary from Google Maps by clicking the Download Button (down arrow icon) on the Google Maps toolbar. The file is in the KML/KMZ format native to Google Earth/Maps. If you have Google Earth installed on your computer you can double click the downloaded file it to open it.
 |
Image 1: Moreau Lake State Park Boundary.
Note: These boundaries are approximate and not official in any way. (Base map source: Google Earth) |
The red outline represents the boundary of the main section of Moreau Lake State Park. The newly added "Lake Bonita" section is shown in blue (lower left). The area in brown (near the top) is the section along the Hudson River and north of Spier Falls Road, The section with the green outline is the area east of the Hudson (
previous post on this here).
 |
| Image 2: The same boundary outlines viewed as an overlay in Google Maps. |
Viewing the boundary layer in Google Maps you might wonder why the outlines I've provided don't match the park boundary shown tinted light green. Most striking is that Maps only shows the main section of the Park. Probably because the data that Google used as the basis for the parks layer was created before the section east of the river was added. That question of "when was the data created" also applies to the new Lake Bonita section. The boundary outline I've provided was digitized from images provided with the press release announcing the land transfer (so again, it is only approximate).
Perhaps the most interesting discrepancy is the area outside of the red outline seen just below and left of Moreau Lake. That's not newly added so, is it in the park or outside of the park? It's probably a data error in Google Maps. No other source that I've seen includes that acreage in the Park and if you zoom in, as seen in Image 3, we see that there are streets located there. I know from having been there that there are houses on those streets so that area is probably not inside the State Park.
 |
| Image 3: The section in green, but outside of the red outline, is probably a data error. (Source Google Maps) |
The outlines I've shared were digitized from base map layers obtained from several sources. My starting point was the official Park map and I edited and added detail using a base map layer from ArcGIS Online (Esri). My point in discussing these discrepancies is that geographic data usually represents a moment in time. If our subject of interest is represented by data that changes continuously then we can consider that data to be out-of-date the second we save it to a database. Even something far less dynamic --a State Park boundary for example-- will change over time and representations provided by varied sources will not necessarily be in agreement. And then there are errors of all kinds and the question of accuracy. But that's another whole story.
As a representation of the real world geographic data is uncertain. And uncertain is not the opposite of certain. It's a lot more complicated than that.
