Exhibit 99.1 Northwest Pipe Company Announces First Quarter 2024 Financial Results • Net sales of $113.2 million increased 14.2% year-over-year, a record for first quarter revenues • Gross profit of $20.1 million increased 21.5% year-over-year, the highest first quarter gross profit in 11 years • Net income of $0.52 per diluted share • Backlog1 of $255 million; backlog including confirmed orders2 of $337 million for the Engineered Steel Pressure Pipe segment (“SPP”) • Order book3 of $52 million for the Prec ...