The Federal Law went into effect on March 30, 1980, outlawing the discharge of RAW sewage into the water ANYWHERE in the United States,
inside the 3 mile limit. That includes all lakes, rivers and streams. $2,000.00 federal fine if you get caught.
Outside the 3 mile limit, you may legally discharge raw toilet waste or the contents of a holding tank out into the water.
Treatment systems are divided into three types:
Type I marine sanitation systems may be used on boats up to and including 65 feet LOA. If your boat is over 65 feet LOA, it requires a Type II system. A Type III system (holding tank, incinerating head, Porta-Potty, composting head, recirculating head) is acceptable for use on all boats, regardless of size. The key there, is that a Type III doesn't allow overboard discharge of any toilet waste (supposedly). The Type I and Type II systems treat the effluent to predetermined levels, and must be tested and certified by the US Coast Guard before they may be used on boats in the U.S.
The definition of No Discharge Zones tends to confuse a lot of people. A No Discharge Zone (NDZ) is an area inside the 3 mile limit, where toilet waste may not be discharged into the water regardless of whether it has been treated by a certified treatment system or not.
These areas are listed on the EPA website, and are declared by the EPA, after an area has submitted an application, has proven that the designation is an environmental necessity in that particular area, and they must also prove that there are a sufficient number of
operable pumpout stations in the given area to accomodate the number of boats in the area.
After investigation, the EPA may then approve the area as a NDZ, or may hand the ball off to the state, and allow them to do it. Here's the list of current NDZ's, by state, from the EPA website:
http://www.epa.gov/owow/oceans/regulatory/vessel_sewage/vsdnozone.html
Keep in mind that if your state isn't listed, it doesn't necessarily mean that there aren't any NDZ's in the state. It means that there are no
specifically named areas in that state. Lakes and rivers that can't be navigated all the way out to the ocean are automatically NDZ's, by definition.
As an example, Pennsylvania isn't on the list but Raystown Lake, near Altoona,
is a NDZ, because you can't navigate from there, out to the ocean. But the Ohio River
is not a NDZ, because it can be navigated all the way down to the Gulf of Mexico.