Earlier quoted context omitted.
The person subject to the complaint prepared stormwater calculations and submitted it as evidence in a legal proceeding. The letter that person received from the board is linked in the article. It states the person is charged and gives them the opportunity for a written response. Civil engineering typically requires a PE.
Engineering generally refers to design and building , of which analysis is a single part. So it's not immediately apparent that Nutt was practicing engineering at all. It's more accurate to say that the kind of projects civil engineers work on generally end up requiring a PE, as a condition of actually being built. Small time civil engineering in your own backyard does not require a PE - eg improving drainage, settin…
The board is investigating a case based on its authority. The authority exists via democratic process originating with the legislative process and state constitution.
The regulation of engineering is within the scope of the states per the US Constitution and established legal precedent.