The United States Coast Guard is the "oldest, continuously serving sea service" in the country. Originally created by Alexander Hamilton, in his capacity as Secretary of the Treasury, as the Revenue Cutter Service in 1790, with the mission to protect trade revenue. It was combined with the U.S. Life-Saving Service to form the U.S. Coast Guard as an active part of the military forces of the United States in 1915.
"The U.S. Coast Guard is authorized to enforce, or assist in the enforcement of, all U.S. Federal laws applicable on, over, and under the high seas and waters subject to the jurisdiction of the United States."
With the role of protecting our nation's waterways, specifically and namely "navigable waterways", the question arises if the Lake of the Ozarks falls under Coast Guard jurisdiction. Unless explicitly exempted by the U.S. Congress, the term "navigable waterway" is defined as territorial seas (e.g. Gulf of Mexico), internal waters influenced by tides(coastal waterways such as bays or harbors), and internal waters used for interstate and foreign commerce(e.g. Mississippi River, Missouri River). Further jurisdiction is granted in regards to pollution control to include tributaries of navigable waterways. One final jurisdiction is provided for designated "regulated areas" on any internal waterway for special events such as races or fireworks displays. (See "Lake of the Ozarks - Navigable or Not")
A large portion of the Midwestern United States falls under U.S. Coast Guard District 8, the largest district in the continental United States. Each district is further divided into command sectors. The Lake of the Ozarks is under the Upper Mississippi River (UMR) sector.
"Sector UMR works closely with state and local law enforcement agencies to enforce recreational boating safety laws. In addition to enforcement on the Western Rivers, Sector UMR boat crews patrol Lake of the Ozarks and Table Rock Lake in Missouri during peak recreational boating periods and during major marine events."
- Sector Upper Mississippi River Year In Review 2012
Working closely with state and local law enforcement is not the same as being the prime enforcement agency. Many people can be forgiven assuming the Coast Guard has authority because the lake easily fits the common sense notion of a "navigable waterway", but the term is more a legal one than descriptive. Interstate and foreign commerce is the key to identifying which internal waterways are identified as "navigable". Vessels cannot reach the ocean from the Lake of the Ozarks, nor is there any commercial traffic such as barges to transport goods, therefore the Lake is by definition, NOT a "navigable waterway" and the U.S. Coast Guard has limited authority over private vessels.
"...the Coast Guard may go aboard any United States vessel at any time, anywhere to conduct a documentation and safety inspection. A search of a U.S. vessel beyond this type of inspection is subject to limitations under the United States Constitution. If a search extends beyond this narrowly defined scope, a court may be asked to evaluate the legality of the search by balancing the individual’s right to privacy in the specific circumstances of the search against society’s interest in detecting criminal conduct."
-- Model Maritime Service Code (1995)
In summary, the USCG can regulate specific areas of the lake during special events for navigation control, can inspect any vessel at anytime for proper documentation and safety, and insure all commercial vessels conform to federal safety requirements and licensed,
But then again...
This PDF is some form I found on the U.S. Corps of Engineers website. It seems to be a reference to changing the status of the Lake of the Ozarks based on the use of the Osage River for commercial barge traffic, prior to the construction of Bagnell Dam. From the form:
"Identify TNW (Traditional Navigable Water): Lake of the Ozarks.
Summarize rationale supporting determination: The water body is presently used, or has been used in the past, or may be susceptible for use (with or without reasonable improvements) to transport interstate or foreign commerce. An Act of Congress dated March 4, 1904, declared the Osage River navigable. The authority is laid out in the 1931 LO Navigational Determination. The Federal Power Commission determined on June 4, 1931 that "the pool or lake formed by the Bagnell dam is navigable waters of the United States. The provisions of Section 10 of the River and Harbor Act*, approved March 3, 1899*, therefore apply to it and the erection of structures within the margins of the lake can be legalized only by the Secretary of War on plans recommended by the the Chief of Engineers of the Army." Further, a letter dated July 21, 1931 from Major General Lytle Brown, then the Chief of Engineers, to the Division Engineer of the Upper Mississippi Valley Division also indicates, under paragraph 3., the following:
"Since the stream was a navigable waterway prior to the construction of the project and all land lying withing (sic) the limits of the project was subject to the right of eminent domain for the reason that it would be necessary or convenient for the development of navigation, it appears logical to conclude that the water flooding the land must be navigable water of the United States." Extent of authority was established to be "at the south line of the southwest quarter of the southwest quarter of Section 15, Township 40 north, Range 22 west, in Benton County, Missouri. This line is approximately 89.3 lake miles above Bagnell Dam, and approximately 0.3 lake miles downstream of the U.S. Highway 65 bridge crossing the Osage River at Warsaw". The Kansas City District Regulatory Branch has determined that the contiguous reach of Lake of the Ozarks extending upstream from lake mile 89.3 at the Section 10 upstream authority limit, Osage River mile 171.0, to approximately lake mile 92.8 at Harry S. Truman Dam is a TNW."
What entity filed this application is as yet, unclear.
*The River and Harbor Act makes it unlawful to build any dam, for any purpose, in any navigable waterway of the United States without the consent of Congress. The Federal Water Power Act of 1920 passed by Congress established the Federal Power Commission with the authority to license the construction of dams in such waterways.