Altering the bed of any of our state waters is illegal without an HPA, permission from the US Army Corps, and a shoreline development permit. This includes placement of "habitat" and "debris" (depending on you viewpoint).
I have yet to report anyone for violating these statutes, although I am considering it for the situation I believe you are thinking of Janna. Mostly because PVC leaches toxics into Puget Sound, (phtalates and vinyl chloride) will never mature like rock, wood, or steel wrecks or debris do over time.
The illegal placement of materials will generate ill will when discovered. Making it harder to work with WDFW, Ecology, and even the Governor's office on Puget Sound issues.
"Hydraulic project" means the construction or performance of work that will use, divert, obstruct, or change the natural flow or bed of any of the salt or freshwaters of the state.
http://apps.leg.wa.gov/RCW/default.aspx?cite=77.55
That the creation of any obstruction not affirmatively authorized by Congress, to the navigable capacity of any of the waters of the United States is hereby prohibited; and it shall not be lawful to build or commence the building of any wharf, pier, dolphin, boom, weir, breakwater, bulkhead, jetty, or other structures in any port, roadstead, haven, harbor, canal, navigable river, or other water of the United States, outside established harbor lines, or where no harbor lines have been established, except on plans recommended by the Chief of Engineers and authorized by the Secretary of War; and it shall not be lawful to excavate or fill, or in any manner to alter or modify the course, location, condition, or capacity of, any port, roadstead, haven, harbor, canal, lake, harbor of refuge, or inclosure within the limits of any breakwater, or of the channel of any navigable water of the United States, unless the work has been recommended by the Chief of Engineers and authorized by the Secretary of War prior to beginning the same.
http://www.nws.usace.army.mil/publicmen ... ion_10.pdf
The legislature finds that the shorelines of the state are among the most valuable and fragile of its natural resources and that there is great concern throughout the state relating to their utilization, protection, restoration, and preservation. In addition it finds that ever increasing pressures of additional uses are being placed on the shorelines necessitating increased coordination in the management and development of the shorelines of the state. The legislature further finds that much of the shorelines of the state and the uplands adjacent thereto are in private ownership; that unrestricted construction on the privately owned or publicly owned shorelines of the state is not in the best public interest; and therefore, coordinated planning is necessary in order to protect the public interest associated with the shorelines of the state while, at the same time, recognizing and protecting private property rights consistent with the public interest. There is, therefor, a clear and urgent demand for a planned, rational, and concerted effort, jointly performed by federal, state, and local governments, to prevent the inherent harm in an uncoordinated and piecemeal development of the state's shorelines.
http://apps.leg.wa.gov/RCW/default.aspx?cite=90.58