Supplemental data

Three layers over the mosaic. tiger_states.parquet is the six-state footprint for clipping the mosaic, which is not masked in the store. nhd_water_bodies.parquet is the inland and near-shore water, for masking the CTrees fold. hf435_wildlands.parquet is the one the viewers draw.

hf435_wildlands.parquet (in use)

The 2022 Wildlands of New England: conserved land that by design lets natural processes run, with no active management. Drawn over the mosaic as boundaries.

Source: Wildlands of New England GIS Data 1900-2022 (HF435), Harvard Forest Data Archive. Foster, D., Johnson, E., Hall, B. (2023). License CC0. Dataset page: https://harvardforest1.fas.harvard.edu/exist/apps/datasets/showData.html?id=HF435

Credit the original when reusing this file: Foster D, Johnson E, Hall B. 2023. Wildlands of New England GIS Data 1900-2022. Harvard Forest Data Archive: HF435.

This is the strict end of the conservation funnel. The project screened over 600 candidate sites against three criteria (wildland intent, management for natural process, permanent protection) and kept 426. That compiles to 1,321,878 acres, 3.3% of New England. Median property is 302 acres, and the list is Baxter State Park, the White Mountain and Green Mountain wildernesses, Acadia, and the TNC reserves rather than town commons and ballfields.

By state: ME 85 properties / 722,838 ac, NH 72 / 233,166, VT 157 / 221,307, MA 57 / 115,933, CT 54 / 28,614, RI 1 / 21.

What changed from the source (see src/landsat_mosaic/wildlands.py):

• Reprojected from EPSG:5070 Albers to EPSG:4326.
• Geometry simplified with tolerance 0.0001 degrees, about 10 m. 628,263 vertices down to 105,447. Adjacent polygons were simplified independently, so shared edges can show small slivers. Do not use this file for area calculations; AcresGIS is the source's own figure.
• Dropped OBJECTID.
• Written as GeoParquet with a covering bbox column. At 426 rows it is a single read; the bbox column is there for readers that want it.

426 polygons (231 MultiPolygon, 195 Polygon), 1.55 MB. Columns: PropID, PropName, FeeOwner, OwnerType1, OwnerType2, OwnerType3, YearOrig (-999 when unknown, 43 rows), W_Deed, W_Federal, W_State, W_MgmtPlan, W_Other, ProtDocs, ThrdPartYN, ThrdPartID, MgmtPlanTy, State, AcresGIS, geometry.

The snapshot is 2022. Land made Wildland since then is not included.

tiger_states.parquet (in use)

The six New England states from Census TIGER/Line 2024, for clipping the mosaic to New England in notebooks and viewers. The store itself is not masked: tiles are whole 4096 px squares and keep NY, Quebec, New Brunswick and the ocean. Clip with this layer where the six-state footprint is wanted.

Source: TIGER/Line Shapefiles 2024, State, U.S. Census Bureau. Public domain (U.S. government work). https://www2.census.gov/geo/tiger/TIGER2024/STATE/tl_2024_us_state.zip

Why raw TIGER and not the cartographic boundary file or Overture (compared 2026-09-07): raw TIGER runs to the 3 nautical mile limit, so bays, harbors and the near-shore band are inside and only open ocean is cut. The 500k cartographic file is shoreline-clipped but generalized by about 100 m, several pixels. Overture division areas for the states are triangulated at the coast and miss about 1,300 km2 of land; their land plus maritime union is the same 3 nmi envelope as TIGER but with a jagged internal seam.

What changed from the source (see src/landsat_mosaic/state_boundary.py):

• Six states selected, reprojected EPSG:4269 to EPSG:4326.
• Kept GEOID, STUSPS, NAME, ALAND, AWATER (lowercased). Dropped the rest.
• A seventh row, kind = "new_england", is the six dissolved into one MultiPolygon (2 parts, 0 holes, 186,447 km2 in EPSG:5070). aland and awater on that row are the sums.
• Not simplified. 22,240 vertices in the dissolved row; simplifying would move the inland borders by up to the tolerance.
• Written as GeoParquet with a covering bbox column.

7 rows, 1.1 MB. Columns: kind ("state" or "new_england"), geoid, stusps, name, aland, awater, geometry.

nhd_water_bodies.parquet (in use, not in git)

Not tracked in this repo: 18.7 MB. Build it once with uv run python src/landsat_mosaic/water.py; the viewer says so in its status line when the file is missing and runs without the mask until then.

Lakes, ponds, reservoirs, estuaries, bays, the near-shore ocean and the wide-river polygons of the six states, from the USGS National Hydrography Dataset High Resolution, for masking water out of the CTrees hexagon fold in pyramid-ctrees-pair.py.

Why this file: CTrees carries a biomass value over open water (zero, or near it, with an uncertainty), not a nodata flag. Without a mask the fold draws hexagons over lakes, and a hexagon on the shore averages lake zeros in with its forest and reads as a low-biomass halo round the water. With it, water leaves the fold at the pixel level: no hexagon over open water, and a shore hexagon is the mean of its land pixels. The viewer's WATER MASK toggle (m) is this layer. It is never drawn.

Source: NHD High Resolution, per-HU4 GeoPackages, U.S. Geological Survey, staged at https://prd-tnm.s3.amazonaws.com/StagedProducts/Hydrography/NHD/HU4/GPKG/ (vintage December 2023). Public domain (U.S. government work). Twelve subregions: 0101 to 0110 (all of hydrologic region 01, New England), 0430 (Lake Champlain, the western half of Vermont) and 0202 (the Hudson, for the Batten Kill, Hoosic and Walloomsac corners of VT and MA).

What changed from the source (see src/landsat_mosaic/water.py):

• Kept NHDWaterbody LakePond (ftype 390), Reservoir (436) and Estuary (493), and NHDArea SeaOcean (445), BayInlet (312) and StreamRiver (460). SwampMarsh (466) is left out: it is vegetated and has biomass.
• Dropped features under 0.01 km2 (1 ha, one CTrees pixel). In HU4 0104 that is 3,321 lake/pond polygons down to 744, and almost none of the area; a sub-pixel pond cannot be masked at 100 m anyway.
• Read with a bbox on the six-state envelope, then kept only features that intersect the dissolved state boundary, so 0430 and 0202 contribute their Vermont and Massachusetts parts and not New York.
• Z dropped, reprojected EPSG:4269 to EPSG:4326.
• Simplified with tolerance 0.0001 degrees, about 10 m. Do not use this file for area; area_km2 is the source's own figure.
• Deduplicated on permanent_identifier across subregion overlaps.
• Written as GeoParquet with a covering bbox column, rows sorted along a Hilbert curve in row groups of 2048, so readers can prune by bbox.

19,379 polygons (3 MultiPolygon), 46,604 km2, 18.7 MB. Of that, 17,080 LakePond (7,120 km2), 255 Reservoir (36 km2), 89 Estuary (3,926 km2, Long Island Sound the largest), 16 SeaOcean (29,931 km2, the band inside the TIGER 3 nmi limit), 4 BayInlet (4,327 km2, the Bay of Fundy) and 1,935 StreamRiver (1,265 km2). Columns: nhd_id, name (GNIS, null for most ponds), ftype, fcode, area_km2, layer ("waterbody" or "area"), huc4, geometry.

The 1 GB of source zips are cached in data/supplemental/nhd/ (gitignored) so a rebuild skips the download.