Oroville Dam

In a grueling mountain application — while aimed downward at a 30-degree angle and steadied by cables from the top — two Wirtgen cold milling machines removed a temporary, emergency-placed concrete surface of the lower part of the great spillway of the Oroville Dam and reservoir in advance of permanent resurfacing.

SACRAMENTO, Calif. (AP) In an unusual reversal, federal regulators agreed to cover about $300 million in repair costs at the Oroville Dam, where a spillway collapse three years ago prompted the evacuation of nearly 190,000 people in Northern California.

On Feb. 7, 2017, a 200-ft. pothole opened up in the main spillway of the Oroville Dam in northern California. With snowpack at 150 percent above normal in the Sierra mountains, and Lake Oroville still rising, officials reduced the amount of flow on the main spillway.

OROVILLE, Calif. (AP) An epic winter of rain and snow has refilled California's reservoirs and pressed into service a spillway at the nation's tallest dam on April 2, a $1 billion structure that drained excess water for the first time since it crumbled two years ago and drove hundreds of thousands to flee the threat of catastrophic flooding.

SACRAMENTO, Calif. (AP) — The federal government has rejected $306 million in reimbursements for California's repair of damaged spillways on the nation's tallest dam, a state agency said March 8. California has so far requested about $639 million from the Federal Emergency Management Agency (FEMA) for the Oroville Dam repairs, said Lisa Lien-Mager of the state's Natural Resources Agency.

California Department of Water (DWR) officials report that the second phase of construction work on the Oroville Dam spillways began on May 8. The second phase will constitute the bulk of work on the lake's spillways. Construction is expected to conclude by the end of 2019.

Crews are making progress on repairs to the Oroville Dam's emergency spillways, the Department of Water Resources said. According to Kiewit Infrastructure West Co. , the company contracted to perform the repairs, work stopped heavy construction on the main spillway over the winter, but plans to start back up in the coming months to meet its January 2019 deadline, Appeal-Democrat reported.

From high-profile infrastructure to politically-charged projects, innovative equipment to billion-dollar builds, the construction industry made a big impact all over the country in 2017. While there were countless projects, events and stories worth talking about throughout the year, here is a list of our editors' top 10 picks:1.

Cracks have appeared in some recently rebuilt portions of the Oroville Dam's $500 million concrete flood-control chute, and federal regulators want to know why. The Federal Energy Regulatory Commission (FERC) sent a letter in October to the state Department of Water Resources (DWR), who operates the California dam, mentioning the small cracks that have surfaced in the new concrete section, and asking what could be done to address the problem, KQED News reported.

Crews worked at a swift pace to replace most of Oroville Dam's main spillway with a new spillway designed to handle water well during flood years. Lake Oroville is about 75 mi. north of Sacramento and about 25 mi. southeast of Chico. The dam is the tallest in the United States.

Independent consultants have expressed concerns over reconstruction plans for the Oroville Dam's main spillway. Part of the spillway is scheduled for a temporary fix with roller compacted concrete (RCC), a material that isn't as strong as structural concrete, which will eventually be used to surface the spillway chute, Mercury News reported.