Alaska Water Level Watch Station Tiers

Data on this portal is grouped into three Tiers: A, B, and C. These tiers are based on CO-OPS specifications.

Tier A

  • Accuracy: 10 cm or better
  • Vertical Control: 5 or more benchmarks, annual leveling, 2nd Order Class 1 or better

Tier B

  • Accuracy: 30 cm or better
  • Vertical Control: 3 or more benchmarks with 3rd Order biennial level OR ellipsoidal referenced via GPS

Tier C

  • Accuracy: greater than 30 cm or unknown
  • Vertical Control: not required

If no Tier is listed, or if the sensor standards are unknown, the data will be assigned Tier C.

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