Final answer:
A waterway can be closed under federal authority based on the commerce clause and under state regulations considering environmental, navigational, and economic factors, as established by decisions like Gibbons v. Ogden and state laws.
Step-by-step explanation:
The authority under which a waterway could be closed is determined by federal and state regulations. A historical reference to establishing the power to regulate commerce, specifically waterborne commerce, is found in the landmark Supreme Court decision of Gibbons v. Ogden (1824). The court ruled that federal law takes precedence over individual state law when it comes to regulating interstate commerce, which at the time included navigation of waterways. This is based on the commerce clause of Article I, Section 8 of the U.S. Constitution. Additionally, state governments have the authority to manage water uses, balancing the needs for public water supply, protection of fish and wildlife, recreation, agriculture, industry, and navigation. Factors considered include the physical, chemical, and biological characteristics of the water body, as well as economic considerations.
For instance, a state could enact legislation that prohibits drilling for oil and natural gas in state-owned waters to protect the environment or public health. Furthermore, the federal government and state government can require waterways to be closed or altered for navigational improvements such as the construction of dams or locks, or in response to environmental concerns, as mentioned with the weir on the Humber River to prevent floods. Therefore, the decision to close a waterway could be based on a multitude of regulations and requirements, depending on the purpose of the closure and the governing authorities involved.