Good point.
There are two major bodies of law governing the discharge of sewage by recreational vessels.
1) 40 CFR 140
http://law.justia.com/us/cfr/title40/40-22.0.1.1.2.0.1.1.html
2) Clean Water Act Section 312
http://www4.law.cornell.edu/uscode/33/1322.html
40 CFR 140 defines marine sanitation devices and sets standards for areas where untreated sewage may not be discharged.
Section 312 of the Clean Water Act gives the EPA the authority to designate a complete prohibition (aka "no-discharge zone") based on a request by a state, which must meet very specific guidelines.
The only place I've been able to identify the issue of "locking out" MSDs is in 40 C.F.R. § 140.3:
----- excerpt -----
Title 40: Protection of Environment
PART 140--MARINE SANITATION DEVICE STANDARD
§ 140.3 Standard.
(a) (1) In freshwater lakes, freshwater reservoirs or other freshwater impoundments whose inlets or outlets are such as to prevent the ingress or egress by vessel traffic subject to this regulation, or in rivers not capable of navigation by interstate vessel traffic subject to this regulation, marine sanitation devices certified by the U.S. Coast Guard (see 33 CFR part 159, published in 40 FR 4622, January 30, 1975), installed on all vessels shall be designed and operated to prevent the overboard discharge of sewage, treated or untreated, or of any waste derived from sewage.
This shall not be construed to prohibit the carriage of Coast Guard-certified flow-through treatment devices which have been secured so as to prevent such discharges.
----- End of excerpt ------
Section 312 also prohibits states from adding regulations (such as locking out equipment):
----- excerpt -----
TITLE 33 > CHAPTER 26 > SUBCHAPTER III > § 1322
(f) Regulation by States or political subdivisions thereof; complete prohibition upon discharge of sewage
(1)
(A) Except as provided in subparagraph (B), after the effective date of the initial standards and regulations promulgated under this section,
no State or political subdivision thereof shall adopt or enforce any statute or regulation of such State or political subdivision with respect to the design, manufacture, or installation or use of any marine sanitation device on any vessel subject to the provisions of this section.
(B) A State may adopt and enforce a statute or regulation with respect to the design, manufacture, or installation or use of any marine sanitation device on a houseboat, if such statute or regulation is more stringent than the standards and regulations promulgated under this section. For purposes of this paragraph, the term "houseboat" means a vessel which, for a period of time determined by the State in which the vessel is located, is used primarily as a residence and is not used primarily as a means of transportation.
----- end of excerpt -----
Full text:
http://www4.law.cornell.edu/uscode/33/usc_sec_33_00001322----000-.html
To summarize:
The
law allows us to carry MSDs which can discharge waste through areas that don't allow us to use them, if they are "secured".
There are standards and regulations (rules) which formalize this.
I'm still looking for those. Again, I'm no lawyer, but I'll bet that locking something with a key meets the definition of "secured".
updated 9/6/08:
That "guidance" issued by the Coast Guard on how to secure the type III MSD discharge is spelled out in 33 CFR 159 Subpart A §159.7(c):
http://ecfr.gpoaccess.gov/cgi/t/tex...&view=text&node=33:2.0.1.5.28.1.179.5&idno=33
" (c) When operating a vessel on a body of water where the discharge of untreated sewage is prohibited by the Environmental Protection Agency under 40 CFR 140.3, the operator must secure each Type III device in a manner which prevents discharge of sewage. Acceptable methods of securing the device include—
(1) Closing each valve leading to an overboard discharge and removing the handle;
(2) Padlocking each valve leading to an overboard discharge in the closed position; or
(3) Using a non-releasable wire-tie to hold each valve leading to an overboard discharge in the closed position."
Note the use of the word "include". This is a list of some acceptable methods, but it does not rule out others. I am still looking to see if there's any rulemaking on this, but in the end I wouldn't be surprised if it's left to the courts to interpret what it means to "secure" the MSD discharge. And I'd still bet on key switches being acceptably "secure".
