The Hassayampa Flood Safe (Walnut Grove Dam, 1890)

[VERIFIED] The Walnut Grove Dam on the Hassayampa River, at 34.1931, -112.5416, failed in the early hours of 22 February 1890 and killed between 70 and 150 people. [PRIMARY] Prescott's Arizona Weekly Journal-Miner reported on 26 February 1890 that Bob Brow's safe "was swept away and no trace has, after the most diligent search, been found of it"; on 5 March that it was thought to be "buried in the sand, as an eddy was formed where his building stood"; and on 12 March that "His safe with its precious contents of $7,000 has not yet been found." [PRIMARY] The paper placed Brow's place about fifteen miles below the dam. [DERIVED] Tracing the river fifteen miles down the channel puts the stretch near 34.085, -112.616, inside the BLM Hassayampa River Canyon Wilderness. [UNKNOWN] No later report of the safe being found has been located. [UNKNOWN] The exact building site.

Case overview: estimated value $7,000 in the safe, as reported by the Arizona Weekly Journal-Miner, 12 March 1890; current status unrecovered; era 1890.

Search area: River miles 13–17 below the dam, roughly 34.108, -112.605 to 34.077, -112.629 (derived from the 1890 distance; not a pinpoint)

Best modern approach: Read the Journal-Miner run for March–June 1890 and the 1890 Yavapai County assessment roll to fix Brow's building, then compare the 1890s channel on historic topographic maps with today's river before any field work.

Evidence and provenance: [VERIFIED] Walnut Grove Dam failure, 22 February 1890, at 34.1931, -112.5416; [VERIFIED] Between 70 and 150 dead; [PRIMARY] Arizona Weekly Journal-Miner, 26 February 1890: the safe "was swept away and no trace has, after the most diligent search, been found of it"; [PRIMARY] Journal-Miner, 5 March 1890: thought "buried in the sand, as an eddy was formed where his building stood"; [PRIMARY] Journal-Miner, 12 March 1890: "His safe with its precious contents of $7,000 has not yet been found"; [DERIVED] About fifteen river miles below the dam: near 34.085, -112.616 (Library of Congress Chronicling America; USGS NHD river trace); [UNKNOWN] No report of recovery located.

Source origin: the earliest traceable published account is Contemporary newspaper coverage (event); later compilation (cache claim) (1890) in Arizona Weekly Journal-Miner, 26 Feb / 5 Mar / 19 Mar 1890 (event). Independent corroboration: yes. Sources that restate one another count as one source, not several.

Why this case is worth researching: The Hassayampa Flood Safe (Walnut Grove Dam, 1890) pairs a documented historical event with an unrecovered-cache claim, which is what the PinPoint Treasure pipeline is built to test — cross-referencing archival sources, geology, mining records, and 1-meter LiDAR terrain where coverage exists. Every claim on this page carries an evidence grade, and grades are never raised to fill a gap.

Recommended workflow for the The Hassayampa Flood Safe (Walnut Grove Dam, 1890) case: (1) read the primary sources and establish which of them are independent of each other, (2) run the cipher engine on any coded material, (3) scan the highest-probability bounding box with LiDAR where coverage exists, (4) cross-check anomalies against NDVI vegetation stress and iron-oxide satellite signatures, and (5) confirm land status before any field work.