The Central Nebraska Public Power and Irrigation District Groundwater Mound Study

Purpose ● Main Objectives  Evaluate the groundwater mound in the vicinity of lands irrigated by CNPPID facilities  Provide an understanding of the temporal and spatial changes of the groundwater mound  Identify factors affecting the groundwater mound

Key Terms ● CSD Groundwater Level Monitoring Reports  UNL-Conservation and Survey Division `

Key Terms ● CSD Wells  Database of water levels from wells used in CSD report

Key Terms ● Study Area

Groundwater Mound Study Recap ● Estimated Mound Volume  CSD well method  Water balance method ● Subareas ● Spatial and Temporal Movement ● Adjustment Impact  Diversions  ET

Groundwater Mound Size and Shape Annual Groundwater Mound Volume

Groundwater Evaluation Water Balance

CSD Mound Volume Compared to Water Balance Mound Volume Mound Volume Calculated using the Water Balance Mound Volume Calculated using CSD Well Data

Water Balance Adjusted Diversions Annual Groundwater Mound Volume No Diversions 50% Diversions 75% Diversions CSD Well Data 125% Diversions 100% Diversions 25% Diversions

Water Balance Adjusted ET Annual Groundwater Mound Volume 95% ET 98% ET 105% ET 102% ET CSD Well Data Un-Adjusted ET

Primary Conclusions ● Groundwater Mound Size and Volume  Increasing trend from the 1950s to  No longer an increasing trend since 2000.

The Future of the Mound ● Declining Surface Water Recharge  Reduced Water Supply in Lake McConaughy (Allocations)  Increased efficiencies (Conservation) average recharge = 145,000 af Since 2000 average recharge = 90,000 af ● Declining Mound  Negative Water Balance

Questions?