The lawyer nominated to run the Superfund toxic cleanup program is steeped in the complexities of restoring polluted rivers and chemical dumps. He spent more than a decade on one of the nation’s most extensive cleanups, one involving Dow Chemical’s sprawling headquarters in Midland, Mich.

But while he led Dow’s legal strategy there, the chemical giant was accused by regulators, and in one case a Dow engineer, of submitting disputed data , misrepresenting scientific evidence and delaying cleanup, according to internal documents and court records as well as interviews with more than a dozen people involved in the project.

The lawyer, Peter C. Wright, was nominated in March by President Trump to be assistant administrator at the Environmental Protection Agency overseeing the Superfund program , which was created decades ago to clean up the nation’s most hazardous toxic waste sites. He is already working at the agency in an advisory role as he awaits congressional approval. If confirmed, Mr. Wright would also oversee the emergency response to chemical spills and other hazardous releases nationwide.

E.P.A. officials pointed to Mr. Wright’s expertise in environmental law and his tenure at Dow as valuable qualifications. The White House on Saturday referred questions to the E.P.A.