Annual Hydrologic Condition Designation

Hydrologic Conditions

Target Flows and Program Goals

The annual hydrologic condition is determined by the total annual flow at the USGS gage near Grand Island, NE.

• If the annual flow is above 1,140,265 AF, the year is classified as “wet."
• If the annual flow is below 679,815 AF, the year is classified as “dry.”
• If the annual flow falls between 679,815 AF and 1,140,265 AF, the year is classified as “normal”.

These thresholds were determined in the PRRIP program document using annual flows at Grand Island from 1947-1994 with the highest 1/3 of years classified as “wet”, the lowest 1/4 of years classified as “dry”, and the remaining years classified as “normal”.

For more information, see these documents:

• Characterization of Hydrologic Conditions to Support Platte River Species Recovery Efforts
• PRRIP 2011 Hydrologic Condition Annual and Periodic Designations