MEMORANDUM

Subject: Estimating E0 use in recreational marine engines

From: David Korotney, U.S. EPA, Office of Transportation and Air Quality

To: EPA Air Docket EPA-HQ-OAR-2015-0111

Recreational marine engines are used in a water environment where there is a much 

greater potential for water contamination of the fuel. For gasoline that contains ethanol, the 

water can separate from the gasoline and cause engine damage. As a result, some recreational 

marine engine owners seek out gasoline without ethanol (E0). 

We investigated the use of E0 in recreational marine engines using information provided 

by stakeholders in response to the June 10, 2015 Notice of Proposed Rulemaking (NPRM), and 

other information. This memorandum is a followup to a previous memorandum entitled, "

Estimating E0 Volume Sold in the U.S. at marinas" by Lester Wyborny that was released along 

with the June 10, 2015 NPRM.

Total gasoline consumption by recreational marine engines is currently about 1.55 billion 

gallons according to a recent estimate from the EPA's NONROAD model.1 However, there is 

no data available to directly demonstrate the fraction of this volume which is E0 versus that 

which is E10. Anecdotal information provided by the National Marine Manufacturers 

Association (NMMA) and others suggesting that owners of recreational marine engines 

preferentially seek out E0 is insufficient to permit quantitative estimation of the actual volume of 

E0 consumed. However, these parties did confirm that the vast majority of recreational marine 

engines are refueled at retail service stations rather than at marinas. While the specific fraction 

that is refueled at retail rather than marinas was not provided, NMMA did indicate that 95% of 

boats are under 26 feet in length and thus are frequently trailered and refueled at the same time as 

the towing vehicle. For the purposes of this memorandum, therefore, we have assumed that 95% 

of recreational marine engines are refueled at retail stations, while 5% are refueled at marinas.

Data provided by NMMA on the number of registered boats in each state does suggest a 

weak correlation with the number of retail stations offering E0 in each state as provided by Puregas.org.

 

1

"NONROAD estimate of fuel use in recreational marine," EPA docket EPA-HQ-OAR-2015-0111
Figure 1

While the scatter in the data is significant, a statistical analysis verified that there is indeed a 

trend (i.e. the pattern exhibited in the figure above is highly unlikely to be purely random). This 

suggests that some retail stations may offer E0 because they are frequented by customers with 

trailered boats. However, the fact that the correlation is weak is evidence that this is not 

consistent among retail stations that offer E0, and that other factors may be at play. A state may 

have a proportionally larger number of boaters than other states, but this does not necessarily 

mean that it will have a correspondingly larger number of retail stations offering E0. Moreover, 

any correlation between the number of boaters in a state and the number of retail stations 

offering E0 in that state is indicative only of the opportunity for the boat owner to refuel on E0, 

not the actual refueling choice boat owners make. Thus, the weak correlation shown in Figure 1 

provides no straightforward mechanism to quantitatively determine the volume of E0 consumed 

by recreational marine engines. 

Given the paucity of data, we considered several different approaches to estimating the 

volume of E0 consumed by recreational marine engines. Each of these is summarized below. 

We have insufficient information at this time to determine which of these three methods provides 

a more accurate estimate of E0 used in recreational marine engines.

Method 1

Marinas

 Assume that all marinas offer both E0 and E10, and boaters are twice as likely to buy E0 as 

E10

1.55 bill gal × 5% = 78 mill gal E0 + E10

1/3 of boat owners buy E10

2/3 of boat owners buy E0

78 × (2/3) = 52 mill gal E0

0

100

200

300

400

500

600

700

800

900

0 200000 400000 600000 800000 1000000

Number of stations offering E0 in a state

Number of registered boats in a state
Retail stations

 Assume that the 10,300 locations offering E0 (according to Pure-gas.org) includes 6300 

marinas (according to Marinas.com), so the number of retail stations offering E0 is 4000

10,300 - 6300 = 4000

 2.6% of all non-marina retail service stations nationwide offer E0

4000 stations offering E0 / 152,000 total retail stations = 2.6%

 Assume that all recreational marine engines refueling at retail stations that offer E0 will always 

refuel on E0

1.55 bill gal × 95% × 2.6% = 38 mill gal

 Total consumption of E0 by recreational marine engines = 90 mill gal

52 + 38 = 90

Method 2

Marinas

 Assume that all marinas offer E0 exclusively

1.55 bill gal × 5% = 78 mill gal E0

Retail stations

 Assume that the 10,300 locations offering E0 (according to Pure-gas.org) do not include any 

marinas, so the number of retail stations offering E0 is 10,300

 6.8% of all non-marina retail service stations nationwide offer E0

10,300 stations offering E0 / 152,000 total retail stations = 6.8%

 Assume that all recreational marine engines refueling at retail stations offering E0 will always 

refuel on E0

1.55 bill gal × 95% × 6.8% = 100 mill gal

 Total consumption of E0 by recreational marine engines = 178 mill gal

78 + 100 = 178

Method 3

Marinas

 Assume that all marinas offer E0 exclusively

1.55 bill gal × 5% = 78 mill gal

Retail stations

 Assume that the 10,300 locations offering E0 (according to Pure-gas.org) do not include any 

marinas, so the number of retail stations offering E0 is 10,300
 While 6.8% of all non-marina retail service stations nationwide offer E0, Figure 1 above 

suggests that the geographic concentration of stations offering E0 may be slightly higher in areas 

frequented by boaters than in areas not frequented by boaters

 Assume that 10% of non-marina retail service stations in areas frequented by boaters offer E0 

(as opposed to the 6.8% assumed in Method 2)

 Assume that all recreational marine engines refueling at non-marina retail stations that offer E0 

will always refuel on E0

1.55 bill gal × 95% × 10% = 147 mill gal

 Total consumption of E0 by recreational marine engines = 225 mill gal

78 + 200 = 225
Estimated number of Marinas by State from Marinas.com*

State

# of 

Marinas State

# of 

Marinas

Alabama 35 Montana UC

Alaska UC Nebraska UC

Arizona 1 Nevada UC

Arkansas 2 New Hampshire 15

California 468 New Jersey 438

Colorado 1 New Mexico UC

Connecticut 255 New York 900

Delaware 21 North Carolina 128

Dist. of Columbia 6 North Dakota UC

Florida 970 Ohio 243

Georgia 33 Oklahoma 1

Hawaii 19 Oregon 57

Idaho 1 Pennsylvania 33

Illinois 74 Rhode Island 153

Indiana 12 South Carolina 65

Iowa UC South Dakota UC

Kansas UC Tennessee 27

Kentucky 34 Texas 67

Louisiana 19 Utah UC

Maine 277 Vermont 34

Maryland 428 Virginia 185

Massachusetts 394 Washington 303

Michigan 414 West Virginia UC

Minnesota 11 Wisconsin 151

Mississippi 18 Wyoming UC

Missouri 8

*The term UC means “under construction” meaning that data collection is incomplete 

Total number of marinas = 6,300