Research/Terra/ 150069
Task evidence / water-feature-selection

Lakes near observed deep-snow areas

PassComputational taskUnpublished draft
Download evidence JSON ↓

The question

150069
How many major lakes in North America are within 20 km of areas with snow cover over 2 feet?
Exact submitted task and declared adaptations
How many major lakes in North America are within 20 km of areas with snow cover over 2 feet?

Task conventions: Major lakes means every original lake/reservoir polygon in the supplied CEC inventory, with no added size/name/type filter. Snow is the frozen 2024-09-30 to 2025-05-20 accumulation raster, original band 1 in inches, not instantaneous snow depth. Deep-snow areas are CLOSED original pixel footprints with finite unmasked snowfall strictly >24 inches after scale/offset; preserve the grid and do not interpolate or simplify. Measure minimum distance from the full original lake geometry to the union of those observed pixel footprints in EPSG:5070, with transformed straight segments, strictly <20000 metres. A lake intersecting deep-snow area has distance zero. This corrects the released reference's distance-to-isolines shortcut, which misses lakes inside deep-snow areas. Invalid lake polygons may be linework make-valid repaired in their original CRS for measurement only; retain all polygon parts, original attributes/IDs and original geometry in the final selection. Count each lake once. The result is the number near OBSERVED deep snow in the supplied US raster, not proof of low snow or absence elsewhere in North America. NoData/outside coverage remains unknown and must be disclosed; do not turn it into a qualifying zero-snow class. Unknown_count in the JSON counts missing/empty original lake geometries only, NOT the geographic snow coverage gap. The coverage_note must explicitly explain that observed-coverage count is not an exhaustive continental assessment. Source and derived data are internal benchmark only.



Publish an inspectable selected-lake artifact with original benchmark_row_id, attributes and geometry. Map optional. End with fenced JSON {count:integer,unknown_count:integer,coverage_note:string,selection:{collectionId,itemId,assetKey}}. State season, units, strict thresholds, projected-distance approximation and incomplete North American snow coverage.

Delivery format: provide the answer object with all fields specified above as final_response on assess_result, alongside the inspected final artifact_refs. This replaces the JSON-code-block formatting requirement above. Blue attaches your explicit selection to the accepted final answer. Finish with a concise ordinary-language answer agreeing with that selected result; do not duplicate the JSON in chat.

Supplied immutable inputs:
[
  {
    "name": "North American lakes, CEC 2023 frozen benchmark source",
    "edition": "CEC North American Environmental Atlas version 4.0 (2023), original benchmark snapshot; benchmark-only use",
    "units": {},
    "collectionId": "blue-generated--[resource id withheld]",
    "itemId": "[resource id withheld]",
    "assetKey": "data"
  },
  {
    "name": "US snowfall, 2024\u201325 frozen season",
    "edition": "2024-09-30 to 2025-05-20",
    "units": {
      "band1": "inches"
    },
    "collectionId": "blue-generated--[resource id withheld]",
    "itemId": "[resource id withheld]",
    "assetKey": "data"
  }
]

Outcome & verification

Independent artifact and delivery checks passed.

Duration
25m 29s
Recorded Blue tool calls
37
Total tokens
1,933,031
Model cost
Not recorded
Application revision
d50497ea9084f29c91b05406688f87035df98d8a
Release
terra-geobenchx-v1

Recorded final answer

I found 4,728 lakes meeting the rule, and 0 lakes had missing or empty original geometry. The selected-lake artifact is attached. This uses the supplied CEC benchmark lakes and the supplied 2024-09-30 to 2025-05-20 snowfall raster, with band 1 in inches, deep snow as strict >24 inches, and lake distance as strict <20,000 m in EPSG:5070. It is only an observed US-coverage result, so NoData and snow outside that footprint remain unknown. ### Limitations - The snowfall raster covers only the supplied US observation footprint, so this can count lakes near observed deep snow there but cannot prove low snow or absence elsewhere in North America. - Distances use EPSG:5070 planar measurement on transformed straight segments, which is the requested approximation rather than a geodesic measurement. - Selection reflects the supplied US snowfall observation footprint only; lakes outside observed snow coverage are not evidence of low snow. - Distance is the requested EPSG:5070 projected straight-segment approximation, not a geodesic measurement. - This is an observed-coverage result from the supplied US snowfall raster, not proof of low snow or snow absence elsewhere in North America. - Distance uses the requested EPSG:5070 projected straight-segment approximation, and NoData or outside-raster areas remain unknown.

Independent checks

These checks are separate from the agent's own assessment. A successful job or an assertion of success is not enough to pass.

Expected count
4728
Reported count
4728
Computation verified
Yes
Answer fulfilled
Yes
Full grading and rubric record
{
  "expectedCount": 4728,
  "actualCount": 4728,
  "expectedMetrics": null,
  "actualMetrics": null,
  "computationCorrect": true,
  "answerFulfilled": true,
  "adjudication": null,
  "qualification": null,
  "reasons": []
}

Recorded investigation findings

The agent's reported hypotheses and assessments, retained as evidence of its process—not independent proof that the answer is correct. Failed calls retain their requested verdict, not an accepted assessment.

run_trial · completed

On a representative Great Lakes slice, does extracting snowfall band 1, reclassifying strictly greater than 24 inches with NoData preserved, polygonizing the qualifying cells, and measuring lake-to-deep-snow distance in EPSG:5070 produce nearby-lake selections and only null distances for missing or empty original lake geometries?

assess_trial · completed · assessment: sufficient

The end-to-end method succeeded on the supplied benchmark inputs and effectively ran at full extent rather than the intended Great Lakes slice. The deep-snow branch produced one dissolved multipolygon target from qualifying snowfall pixels, the nearest-distance step measured all 13,135 supplied lakes in EPSG:5070 with onInvalidSource=make-valid, and the strict <20,000 m filter selected 4,728 lakes. The distance summary reported unknownSourceCount=0 and repairedSourceCount=5, so the method preserves original lake rows while limiting unknowns to missing or empty source geometry. The selected-lake output retained original benchmark_row_id, attributes, and geometry, with distinct benchmark_row_id count matching the selected count.

assess_result · completed · assessment: sufficient

The current published selected-lake artifact contains 4,728 original CEC lake/reservoir polygons within the requested strict distance of the observed deep-snow footprint. It preserves benchmark_row_id, original attributes, and geometry, includes zero-distance intersections, and keeps every selected lake unique. The current distance summary confirms EPSG:5070 geometry distance, one dissolved deep-snow target union, unknownSourceCount=0, and repairedSourceCount=5 for measurement only.

assess_result · completed · assessment: sufficient

The current final outputs support a count of 4,728 selected lakes and an unknown_count of 0 missing or empty original lake geometries. The selected-lake artifact is inspectable at blue-generated--[resource id withheld] / [resource id withheld] / data. The supporting distance summary confirms EPSG:5070 geometry distance, unknownSourceCount=0, and repairedSourceCount=5 for measurement only.

Recorded workflow

  1. 01

    Strict deep-snow mask

    Recorded raster-reclassify · succeeded

  2. 02

    Polygonize qualifying snowfall cells

    Recorded raster-polygonize · succeeded

  3. 03

    Lakes within 20 km of observed deep snow

    Recorded output · succeeded

  4. 04

    Deep-snow distance summary

    Recorded output · succeeded

  5. 05

    Measure lake distance to deep snow

    Recorded vector-nearest-distance · succeeded

  6. 06

    Supplied CEC lakes

    Recorded source · succeeded

  7. 07

    Select lakes within 20 km

    Recorded vector-filter · succeeded

  8. 08

    Extract snowfall band 1

    Recorded raster-extract-band · succeeded

  9. 09

    Supplied snowfall raster

    Recorded source · succeeded

  10. 10

    Flag unknown lake geometries

    Recorded vector-filter · skipped

  11. 11

    Strict deep-snow mask

    Recorded raster-reclassify · succeeded

  12. 12

    Polygonize qualifying snow cells

    Recorded raster-polygonize · succeeded

  13. 13

    Measure lake distance to deep snow

    Recorded vector-nearest-distance · succeeded

  14. 14

    Trial lakes source

    Recorded source · succeeded

  15. 15

    Select lakes within 20 km

    Recorded vector-filter · succeeded

  16. 16

    Extract snowfall band 1

    Recorded raster-extract-band · succeeded

  17. 17

    Trial snowfall source

    Recorded source · succeeded

  18. 18

    Polygonize qualifying snow cells

    Recorded output · succeeded

  19. 19

    Measure lake distance to deep snow

    Recorded output · succeeded

  20. 20

    Select lakes within 20 km

    Recorded output · succeeded

  21. 21

    Select unknown-geometry lakes

    Recorded output · succeeded

  22. 22

    Select unknown-geometry lakes

    Recorded vector-filter · succeeded

Activity

Recorded actions

Recorded observable actions only, not private reasoning. Raw payloads, geometry, private links and credentials are omitted; full evidence is retained privately. Activity/workflow lists bounded at 500 entries.

  1. Progress update

    I’m checking the supplied lake and snowfall inputs first, then I’ll test the exact deep-snow and distance method on a small private slice before I save the full workflow. After that I’ll run the full analysis, inspect the selected lakes, and give you the counted result with the selected-lake artifact.

  2. get_analysis

    Recorded tool call · completed

  3. get_collection

    Recorded tool call · completed

  4. get_collection

    Recorded tool call · completed

  5. Progress update

    I found the supplied benchmark inputs and their bounds. Next I’m checking the exact item identities and available processor contracts so I can test the strict >24 inch snow mask and the lake-distance calculation without guessing any tool names or parameters.

  6. list_processors

    Recorded tool call · completed

  7. get_tool_help

    Recorded tool call · completed

  8. get_item

    Recorded tool call · completed

  9. get_item

    Recorded tool call · completed

  10. get_tool_help

    Recorded tool call · completed

  11. describe_processors

    Recorded tool call · completed

  12. describe_processors

    Recorded tool call · completed

  13. describe_processors

    Recorded tool call · completed

  14. describe_processors

    Recorded tool call · completed

  15. get_tool_help

    Recorded tool call · completed

  16. get_tool_help

    Recorded tool call · completed

  17. get_tool_help

    Recorded tool call · completed

  18. get_tool_help

    Recorded tool call · completed

  19. get_tool_help

    Recorded tool call · completed

  20. get_tool_help

    Recorded tool call · completed

  21. get_tool_help

    Recorded tool call · completed

  22. update_analysis_brief

    Recorded tool call · completed

  23. Progress update

    I’ve got the exact processor contracts. I’m now running a small end-to-end trial over a Great Lakes slice to confirm three things together: the strict >24 inch mask preserves NoData, the polygonized deep-snow footprint behaves like the observed pixel union, and the nearest-distance step returns nearby lakes with original geometry plus unknowns only for empty source geometry.

  24. run_trial

    Recorded tool call · completed

  25. get_trial_report

    Recorded tool call · completed

  26. Progress update

    The first trial gave me an important surprise: the exact supplied items were not clipped by the trial source-area hint, so the run actually processed the full supplied snow and lake inputs. That is useful for your task, but I still need to inspect the trial report, record that finding clearly, and then save the tested full-extent method as the production workflow instead of pretending the slice clip worked.

  27. assess_trial

    Recorded tool call · completed

  28. Progress update

    I’ve confirmed the method works, and I corrected the one mistaken assumption: the source-area hint did not clip exact supplied items, so I’m saving the production workflow with the full benchmark scope spelled out explicitly and without that misleading local clip. After it validates, I’ll run it and inspect the published selected-lake artifact and supporting summary before I answer.

  29. propose_workflow

    Recorded tool call · completed

  30. Progress update

    The saved workflow is ready, but only the lake layer was bound to a requested result. I’m adding the distance-summary value output too, so the final machine-readable answer has an explicitly bound supporting result for unknown_count and method metadata before I run anything.

  31. propose_workflow

    Recorded tool call · completed

  32. get_analysis

    Recorded tool call · completed

  33. execute_workflow

    Recorded tool call · completed

  34. Progress update

    The saved full workflow finished while the turn was interrupted. I’m inspecting its exact outputs now so I can verify the selected-lake artifact, the distance summary, and the final count before I record the result.

  35. inspect_workflow_results

    Recorded tool call · completed

  36. Progress update

    The workflow outputs are ready. I’m pulling the final selected-lake layer and the distance summary now so I can verify the current count, unknown_count, retained fields, and the exact artifact identity before I record the result.

  37. inspect_artifact

    Recorded tool call · completed

  38. inspect_artifact

    Recorded tool call · completed

  39. inspect_artifact

    Recorded tool call · completed

  40. inspect_artifact

    Recorded tool call · completed

  41. inspect_artifact

    Recorded tool call · failed

  42. Progress update

    I’ve already verified the count and method from the current workflow outputs. I’m only refreshing the final lake preview receipt now, using Blue’s own retry hint, so the final assessment cites the current selected artifact rather than the earlier trial copy.

  43. inspect_artifact

    Recorded tool call · completed

  44. assess_result

    Recorded tool call · completed

  45. assess_result

    Recorded tool call · completed

  46. update_analysis_brief

    Recorded tool call · completed

|||

© 2026 Exia Labs, Inc.