Marble Quarry hiker-biker campsite (C&O Canal towpath mile 38.2)

public land records

Researched — The record is detailed and internally consistent, and the coordinates land where the managing agency says this site is.

NPS Chesapeake & Ohio Canal NHP camping pages, read 2026-08-13 (nps.gov/choh/planyourvisit/camping.htm and .../primitive-campsites.htm): hiker-biker campsites are 'No fee; first-come, first-served; no reservations.' 'Stays limited to one night per site, per trip.' Each has 'chemical toilet, picnic table, firepit, and non-potable well water'; the well water is NON-POTABLE and must be filtered, chemically treated or boiled, and is 'turned off from mid-November to mid-April each year.' Sites hold five to ten tents. Hiker/biker access only -- most sites sit 1-5 miles from the nearest parking, so this is not a drive-up site. Coordinate = OSM node/2021563182 ('Marble Quarry'), VERIFIED by projecting it onto the OSM C&O towpath relation 1392951: it lands at towpath mile 37.79 against the NPS-published mile 38.2 (delta -0.41 mi) and sits 43 ft from the towpath centreline. County CONFIRMED as Montgomery County, MD via the FCC Census Block API, matching the county NPS files it under. Nearest town: Poolesville ~4.7 mi. 'Nearest town' is straight-line distance to the nearest OSM place=city/town/village and is NOT a driving distance; along the Potomac the nearest named place is often across the river in VA or WV with no nearby bridge. Ingest 2026-08-13. --- REVIEWED 2026-08-19 (nightshift-verified) --- SOURCE RE-READ. Both NPS pages this row rests on were re-fetched today and both still say what the row records, verbatim: nps.gov/choh/planyourvisit/camping.htm and nps.gov/choh/planyourvisit/primitive-campsites.htm (page footer: 'Last updated: November 19, 2025'). Still present word for word: 'No fee; first-come, first-served; no reservations.'; 'Stays limited to one night per site, per trip.'; 'All sites have: chemical toilet, picnic table, firepit, and non-potable well water.'; 'Well water at hiker-biker campsites is non-potable. Water is not treated and not for drinking or cooking. If you use this water, you are advised to filter, chemically treat, or boil before use. Water is turned off from mid-November to mid-April each year.'; 'Hiker-Biker campsites can fit a maximum of five to ten tents, depending on the campsite.' The primitive-campsites page's 'List of Hiker-Biker Campsites' still holds exactly 31 entries, and all 31 of our rows matched one each on BOTH name and towpath mile, with nothing left over on either side. This row's entry on the NPS list is under the 'Montgomery County, MD' heading, which matches the county the coordinate actually falls in (below). COORDINATE RE-VERIFIED THREE WAYS, recomputed in this fire rather than taken on trust. (1) TOWPATH PROJECTION: re-projected onto OSM relation 1392951 ('Chesapeake and Ohio Canal Towpath (Maryland)', 151 member ways, all with geometry, stitched end-to-end with no join gap over 50 m, total 180.08 mi). This row lands 43 ft from the towpath centreline, at relation mile 33.37, i.e. -0.29 mi from the NPS-published mile once the constant 4.53 mi is added back -- that constant is the District of Columbia section the Maryland-only relation omits, and it is corroborated independently by 184.5 (the canal's published length) minus 180.08 = 4.42 mi. Across all 31 sites the residual never exceeds 0.44 mi and the distance off centreline never exceeds 195 ft. (2) OSM CAMPSITE: this row sits 0 m from an independently mapped OSM feature node/2021563182 ('Marble Quarry'), tagged camp_site, whose name matches the NPS site name. (3) NPS'S OWN COORDINATES: this row sits 10 m from a point in the NPS Public POIs national dataset (mapservices.nps.gov/arcgis/rest/services/NationalDatasets/NPS_Public_POIs_Geographic/MapServer/0, queried WHERE UNITCODE='CHOH' on 2026-08-19; 524 POIs returned, 34 of POITYPE 'Primitive Campsite') whose POITYPE is 'Primitive Campsite'. All 31 rows matched a DIFFERENT NPS pin one-to-one -- no pin was claimed twice -- and 30 of the 31 matched within 88 m. Six NPS campsite/campground POIs matched no row of ours; the park separately operates reservable fee drive-in campgrounds and a permit-only group site, which are correctly outside this free hiker-biker set, but I did not individually identify those six and am not claiming to have. COUNTY re-confirmed as Montgomery County, MD (state FIPS 24) via the US Census geocoder (geocoding.geo.census.gov, benchmark Public_AR_Current / vintage Current_Current, queried 2026-08-19). DUPLICATE CHECK, matched on COORDINATES and not on name: the nearest already-published-or-approved camp anywhere in the leads DB is rowid 2298 ('Dispersed camp — Frederick County, MD', published) at 36807 m -- not a duplicate; and no pending Maryland lead is within 250 m of any other. STATUS -> approved.

US DOE Alternative Fuels Data Center station locator, snapshot 2026-09-16. Straight-line miles to the nearest public, open, unrestricted station; restricted and planned units are shown but never counted.

On the agency's books. The land manager inventoried this site, so its existence is not in question — current conditions are. Nobody from here has camped it recently.