Some of the Federal regulations:

• P.L. 104-332 - National Invasive Species Act of 1996
  • 16 USC CHAPTER 67 - AQUATIC NUISANCE PREVENTION AND
    CONTROL
• P.L. 101-646 - Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990
• Title 7, Chapter 61- Federal Noxious Weed Act of 1974
  • This US code expressly prohibits the interstate commerce of noxious weeds and allows for the warrant less search and seizure of said weeds.  This law also deals with the required management of noxious weeds on Federal lands. 
• Title 18, Part 1, Chapter 3, Section 46- Transportation of Water Hyacinths
  • 
    (a) Whoever knowingly delivers or receives for transportation, or transports, in interstate commerce, alligator grass (alternanthera philoxeroides), or water chestnut plants (trapa natans) or water hyacinth plants (eichhornia crassipes) or the seeds of such grass or plants; or   
    (b) Whoever knowingly sells, purchases, barters, exchanges, gives, or receives any grass, plant, or seed which has been transported in violation of subsection (a); or   
    (c) Whoever knowingly delivers or receives for transportation, or transports, in interstate commerce, an advertisement, to sell, purchase, barter, exchange, give, or receive alligator grass or water chestnut plants or water hyacinth plants or the seeds of such grass or plants -    Shall be fined under this title, or imprisoned not more than six months, or both.
• Executive Order 13112
  On February 3, 1999, Executive Order 13112 was signed establishing the National Invasive Species Council. The Executive Order requires that a Council of Departments dealing with invasive species be created. Currently there are 10 Departments and Agencies on the Council.
• The Lacey Act (P.L. 97-79, 16 U.S.C. 3371-3378)
  This law is triggered by  interstate transport in conjunction with any violations of state law.

• Link to SC  Laws & Regulations

FEDERAL NOXIOUS WEED LIST
This list contains both terresterial and aquatic species

 Aquatic/Wetland
• Azolla pinnata (Azollaceae) (mosquito fern, water velvet)
• Caulerpa taxifolia (Caulerpaceae) (Mediterranean clone of caulerpa) Eichhornia azurea (Ponterderiaceae) (anchored waterhyacinth)
• Hydrilla verticillata (Hydrocharitaceae) (hydrilla)
• Hygrophila polysperma (Acanthaceae) (Miramar weed)
• Ipomoea aquatica (Convolvulaceae) (Chinese waterspinach)
• Lagarosiphon major (Hydrocharitaceae) (Oxygen weed)
• Limnophila sessiliflora (Scrophulariaceae) (ambulia)
• Melaleuca quinquenervia (Myrtaceae) (melaleuca)
• Monochoria hastata (Pontederiaceae) (monochoria)
• Monochoria vaginalis (Pontederiaceae) (pickerel weed) Ottelia alismoides (Hydrocharitaceae) (duck-lettuce)
• Sagittaria sagittifolia (Alismataceae) (arrowhead)
• Salvinia auriculata (Salviniaceae) (giant salvinia)
• Salvinia biloba (Salviniaceae) (giant salvinia)
• Salvinia herzogii (Salviniaceae) (giant salvinia)
• Salvinia molesta (Salviniaceae) (giant salvinia)
• Solanum tampicense (Solanaceae) (wetland nightshade)
• Sparganium erectum (Sparganiaceae) (exotic bur-reed