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Aaron,
Whether the zero elevation contour of the 2 foot contour interval, State lidar derived contours is represented/shown depends if the lidar data was originally flown at mean tide or lower. If the area of interest was flown at a higher tide level than just below about mid-tide then there will unlikely be any lidar data to derive the zero contour with. Also note a zero elevation in the lidar data which is on the NAVD88 vertical datum is unlikely to be mean sea-level as it might be if the NGVD29 vertical datum is used. The State lidar data is collected using the NAVD88 vertical datum which is not a mean sea-level  datum. NGVD29 was a mean sea-level datum.

Jon Giles
Sebago Technics, Inc.
207-200-2128

From: Maine GeoNews [mailto:[log in to unmask]] On Behalf Of Aaron Gilbreath
Sent: Friday, September 29, 2017 3:55 PM
To: [log in to unmask]
Subject: sea-level in 2' contour shapefiles?

Hello Everyone,
    I was wondering if anyone could tell me how sea-level is zeroed in the 2' contour layers on the Maine GIS site?  Is it from low tide, high tide, or mean tide level?  Thanks in advance, and I apologize in advance if this answer is obvious.  I didn't see it in the metadata.
Thanks,
Aaron

Aaron Gilbreath
148 East Main St
Yarmouth, ME 04096
(207) 841-4805
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