Two-Stroke Vessel Engines

    Facts About Two-Stroke Vessel Engines

  • Two-stroke engines are not "banned" for use on all waterways in California, nor is there any plan to do so.
  • Carbureted and electronic-injection two-stroke engines are considered high-emission engines. Generally, these engines were manufactured prior to 1999.
  • A carbureted two-stroke engine can emit up to 25-30 percent of its fuel unburned into the water or atmosphere, which is why high-emission engines are prohibited on some lakes.
  • There are no salt-water or river restrictions in California on high-emission two-stroke engines, excluding personal watercraft (vessels such as Jet Skis) bans in some areas. For example, San Francisco has prohibited personal watercraft within 1200 feet of its shoreline. See "Local Restrictions" on our web page below for a list of lakes.
  • Direct injection two-stroke engines, made since 1999, are considered clean emission engines and can be used on every water body in California, with some exceptions not related to emission limits.
  • A direct injection two-stroke engine will normally have a label sticker (with 1 to 3 stars) on its engine cover indicating that it meets California Air Resources Board emission regulations for 2001, 2004, and 2008 for vessel engine manufacturers.


There is no statewide prohibition on the use of high emission two-stroke vessel engines. A number of cities, counties or districts have followed state law allowing local public agencies to regulate boating in certain categories. State law allows local public agencies to regulate boating in certain categories. Three of those apply here and are listed below:

      1. Speed Zone
      2. Special-use Areas
      3. Sanitation and Pollution Control

A special-use area is all or a portion of a waterway that is set aside for specified activities to the exclusion of other incompatible uses or activities. Below is a list of waterways with local personal watercraft (PWC) or two-stroke bans or restrictions. (ALWAYS CHECK WITH THE LOCAL WATERBODY MANAGER ABOUT UPDATED RESTRICTIONS.)

Agency/Waterway Type Effective Date
Anderson and Calero Reservoirs, Santa Clara Valley Water District - Allow PWCs that meet CA Air Resources Board 2001 standards. May implement further restrictions if any gas-related chemical contamination detected in periodic water sampling. 3 July 2004
Anderson Reservoir -170 watercraft per day allowed. Calero Reservoir - 60 to 70 watercraft per day allowed. Coyote Reservoir -1 watercraft per six surface acres (Santa Clara Valley Water District Reservoirs) 3 Aug 2004
Bass Lake, County of Madera – Area set aside for PWC. 1, 2 Jun 1995
Berkeley Marina – No PWC within 1500 ft. of the shoreline or fishing pier except in the 200 ft. wide access corridor designated by Harbormaster from a boat launch ramp at marina to a point further than 1500 ft. from shoreline. 2 2006
Canyon Lake, County of Riverside – No PWC. 2 Jun 1991
City of Carlsbad – PWC restricted on part of Agua Hedionda Lagoon. 1, 2 May 1994
City of Los Angeles – Pier 300 shallow water habitat. No PWC. 2 Apr 1993
City of Pacifica – No PWC on specified ocean beaches. 2 Apr 1990
City and County of San Francisco – No PWC within 1,200 ft. from shoreline (with exceptions). 2 Oct 1998
City of Sausalito – No PWC launching or retrieving. 2 Apr 1994
Collins Lake Recreation Area, Collins Lake (private) – No PWC. 2 May 1991
County of Marin, All Waterways – No PWC. 2 Nov 1999
County of Santa Cruz – PWC prohibited within 300 yds. of shore, except to launch or land. 2 Jun 1990
Coyote Lake – Max. 35 PWC per day. From May 1-June 1, powerboats allowed with receipt issued within past 2 days from any of 5 area stations selling non-MTBE gas. 3 May 2000
Diamond Valley Lake and Lake Skinner - No PWC. Only engines that are 4-stroke, 2-stroke equipped with direct fuel-injection or 2-stroke engines that comply with 2001 or later CA Air Resources Board emissions standards and use MTBE-free fuel.
  • No PWCs of any type are allowed.
  • Boats shall not pull individuals or any recreational equipment (e.g., inner tubes, skis, boards, etc.).
  • All boats must be a minimum of 12 feet in length, minimum of 42 inches wide, and must have at least 12 inches of freeboard at idle speed.
  • Multi-hulled vessel without solid and fixed decking shall not be allowed.
  • Only sea kayaks at least 10 feet in length that provide seating for all passengers inside the craft.
  • Rolling over kayaks is prohibited
  • Boats with sink drains and flush toilets must have the sinks and toilets rendered inoperable, or designed so that no waste can be discharged into the lake.
  • Dye tablets may be added by lake personnel to test for leaks
3 Jun 2003
Donner Lake, Town of Truckee –- Prohibition of high emission two-stroke engines only if water fails to meet State drinking water standards. 3 July 1999
Farallones National Marine Sanctuary – No PWC off Sonoma and Marin County coasts, from Bodega Head to Rocky Pt., near Stinson Beach. Federal Oct 2001
Lakes Tahoe, Cascade, Fallen Leaf, and Echo - Dept. of Boating and Waterways and Tahoe Regional Planning Agency – Motorboats must meet 2001 CA Air Resources Board emissions standard. (Carbureted and NON-direct fuel injection engines prohibited) 2 Jun 1999
Los Vaqueros Reservoir, Contra Costa Water District – All motorboats are prohibited. 3 Aug 1998
Millerton Lake, Friant, CA. Read the public notice. 3 May 2013
Mission Bay, City of San Diego – Area set aside for PWC. 2 July 1988
Monterey Marine Sanctuary  

The four zones and access routes are:

  1. The approximately one nautical mile squared (NM²) area off Pillar Point Harbor from launch ramps, through harbor entrance to the northern boundary of Zone One bounded by flashing 5-second breakwater entrance light and horn located at the seaward end of the other west breakwater.
  2. The approximately five NM² area off of Santa Cruz Small Craft harbor from harbor launch ramps, through harbor entrance, and then along a 100 yard wide access route southwest along a true bearing of approximately 196- (180-magmetic) to the whistle buoy.
  3. The approximately five NM² area off of Moss landing Harbor from harbor launch ramps, through harbor entrance, and then along a 100 yard wide access route due west to the eastern boundary of Zone Three
  4. The approximately five NM² area off Monterey Harbor from harbor launch ramps to the seaward end of the U.S. Coast Guard Pier, and then along a 100 yard wide access route due north to the southern boundary of Zone Four.

*The National Oceanic and Atmospheric Administration definition of a Motorized personal water craft means any motorized vessel that is less than fifteen feet in length as manufactured, is capable of exceeding fifteen knots, and has the capacity to carry not more than the operator and one other person while in operation. The term includes, but is not limited to: jet skis, wet bikes, miniature speed boats, air boats, and hovercraft.

Federal July 1996
Pine Crest Lake, County of Tuolumne – No PWC. 2 Mar 1990
Point Reyes National Seashore and Golden Gate National Recreation Area, National Park Service – No PWC. Federal Apr 2000
Scotts Flat Lake, County of Nevada – No PWC. 2 Sep 2004
Seal Slough (Marina Lagoon), City of San Mateo – No PWC. 2 July 1988
San Pablo Reservoir, East Bay Municipal Utilities District – (a) Only four-strokes or equivalent emission level allowed. 3 Jan 2000
San Luis Reservoir State Recreation Area (San Luis Reservoir, O'Neill Fore Bay, and Los Banos Creek Reservoir). Read the public notice. 3 July 2015
Whiskeytown Lake, National Park Service -No PWC Federal Apr 2002



Explanation Of Two-Stroke Vessel Engine
Regulations And Restrictions

Boaters may have heard erroneous information from vessel repair shops, mechanics, or marine retailers that they will no longer be able to legally use their vessel on California waterways.

The fact is, there is no statewide prohibition on the use of high emission two-stroke vessel engines, and there is no plan to prohibit them.

The state regulations, from the California Air Resources Board (ARB) Recreational Marine Engine Program, are directed at the manufacture and sale of NEW marine gasoline two-stroke engines. ("New" means the engine has never been sold to an end-user.) The ARB regulations ordered vessel engine manufacturers to build cleaner emission engines meeting increasingly strict standards with steps in 2001, 2004, and 2008. These ARB regulations do not affect the use of any vessels on waterways, other than the fact that consumers will obtain improved gas mileage from the new models now on the market.

A number of cities, counties or districts have adopted ordinances on drinking water reservoirs that restrict or ban the use of high emission, carbureted or electronic fuel injection (EFI) two-stroke marine engines.

There are no salt-water or river restrictions based solely on high emission vessel engines.

Cleaner technology direct-injection two-stroke marine engines, manufactured since 1999, can be used on all waterways in California, except for some waterways that have generic prohibitions, such as banning all motorboats or all personal watercraft.

We hope this clears up any confusion about this subject. Should you have any questions, please contact 


Editor's Note: The California Air Resources Board's new regulations requiring manufacturers to reduce emissions from new outboard and personal watercraft engines will become effective in three stages--2001, 2004 and 2008. ARB believes that by 2010, the regulations will achieve a 30-ton-per-day reduction of hydrocarbons and oxides of nitrogen over the current U.S. EPA standards, and 44 tons per day by 2020. ARB estimates that carbureted two-stroke engines discharge up to 20-30 percent of their fuel unburned into the air and water.

ARB will also require that each new engine be provided with a label to certify that the engine complies with the new regulations. The label will feature from one to three stars, depending on the emission level, with three stars indicating the lowest level of exhaust emissions.

No, the Air Resources Board has developed standards based on actual emission levels, regardless of engine type, for new outboard and personal watercraft engines. These standards do not ban two-stroke engines. The ARB's emission standards reflect currently available clean-burning engine technology.
The regulations apply to gasoline-powered outboard engines, personal watercraft (for example, Jet Skis, and Wave Runners) and jetboats only. Sterndrive and inboard engines are not included in ARB's regulations at this time, but are being studied for future emission reduction programs.
No. The regulations adopted by the ARB set exhaust emission standards for engines sold in California starting in 2001. the regulations do not require the retrofitting of pre-2001 model year engines, or require the purchase of new engines
Yes, there are no restrictions on the sale of pre-2001 model year engines. In addition, dealers may continue to sell trade-in engines and pre-2001 model year engines.
Several water agencies have recently restricted access to their lakes or reservoirs in order to protect or improve water quality. Specifically, Lake Tahoe, the East Bay Municipal Utility District and the Santa Clara Valley Water District have each adopted restrictions for their waterways because of concerns about gasoline constituents found in their waters. These actions have been taken on a lake-by-lake basis and have been local rather than statewide.
Manufacturers have already introduced a variety of engines between 2 and 225 horsepower that comply with the new regulations. Several two-stroke direct injection engines have been available on the market. These engines offer consumers improved fuel economy, lower oil consumption, and improved idle performance while significantly reducing pollution and maintaining the performance characteristics of traditional two-strokes. Four-stroke engines are also available that comply with the new regulations. These have been available to consumers for many years and also offer improved fuel and oil economy. The ARB offers the following related "New Standards for Cleaner Watercraft" and "Watercraft Labeling." Call 1-(800) END-SMOG to order.
The marine engine regulations require manufacturers to apply an environmental label to new outboard engines and personal watercraft. These labels clearly identify the emissions performance of new engines meeting the regulations. The intent of these labels is to help consumers choose clean technology engines when making a purchase decision.