Nordby Wine Caves recently partnered with Njirich & Sons, Inc., to rehabilitate Oakdale Irrigation District (OID) Tunnels 3 and 4, located northeast of Oakdale, California. OID has delivered irrigation water to 55,000 acres of farmland in the Central Valley for more than a century. Constructed in the early 1900s, Tunnels 3 and 4 needed significant repairs to restore stability and improve water flow efficiency. Collectively spanning about 2,250 feet, the 8-to-20-foot tunnels were originally built without lining or ground support, leaving them vulnerable to erosion and structural degradation. Erosion had caused stress fractures, ground instability, and flattened tunnel crowns. To address its aged infrastructure, OID developed a Water Resources Plan (WRP) to modernize and rebuild its system to meet the needs of its changing customer base. Nordby Wine Caves widened and reshaped the tunnels to an arch shape to improve stability of the tunnel ground and increase flow rate capacity. We i