Table 12 – Quantity of PCBs Released to Each Great Lake By Pathway (kg / year) 1

Great Lake

Superior

Michigan

Huron

Erie

Ontario

Atmospheric Emissions

1,536 (1)

[1994 to ‘95]

50-500 (5)2

64 (4)

[1996]

Total Estimated Emissions (GL States & Ontario) [1996]

16.053 (7)

GL States Emissions (not incl. Ontario point & area sources)

1.45 (1) [1996]

Wet deposition

58 (6)3

50-250 (1)4

180 (6)3

21 (6)3

58 (6)3

Dry deposition

27 (6)3

16-1,100 (1)4

16 (6)3

5.7 (6)3

Wet and dry [IADN: 1996]

85-156 (3)

42 (1,3)

34 (3)

Net gas transfer [1991-1993]

-1,700 (6)3

-2,700 (6)3

880-1,329 (1)4

-420 (6)3

-440 (6)3

Absorption

320 (6)3

390 (6)3

340 (6)3

130(6 )3

Volatilization

-2000 (6)3

-3,100 (6)3

-760 (6)3

-560 (6)3

-440 (4)5

Tributaries

PCB loadings to lakes from tributaries6

325 (1)

[1994 &’95]

100-500 (5)2

440 (4)

[1995]

Point and Non-Point Sources

Point source discharges to basin tributaries [1990-1999]7

23.3 (2)

397.31 (2)

81.09 (2)

5.54 (2)

U.S. TRI releases to water [1997]8

1814.4

Runoff (U.S.) [1996]

15 (3)

Point & Non-point [1990-1995]

100 (4)

Spills [1990-1999]

0.454 (1)

Notes:

1      All quantities are in kilograms per year, unless otherwise stated. The year the data were collected is either provided in square brackets in the table or in the notes.

2      Estimates are partially based on old or very limited data; they should be viewed as rough approximations only. See Lake Huron Initiative Action Plan (2000), Chapter 3, Table 1.

3      Average estimated atmospheric loadings (1991-1993). See Great Waters Report, 2nd Report to Congress.

4      Estimates come from three studies (1993 to 1995). See Lake Michigan LaMP 2000, pp. 5-59 – 5-60

5      Non-point source loadings information (1990-1995). See Lake Ontario LaMP (1998), pp. 57-58.

6      The Fox River is the largest tributary loading of PCBs to Lake Michigan (186 kg/yr) followed by the Grand Calumet (37.2 kg/yr) and Kalamazoo (36.8 kg/yr) rivers. For Lake Ontario, the other Great Lakes provide the largest tributary source of PCBs (302 kg/yr) followed by the Niagara River basin (138 kg/yr).

7      Estimates are for the U.S. side of the basin only.

8      U.S. Toxics Release Inventory (TRI) data show actual releases to the environment for 1997. The data represent releases within the Great Lakes states (not Ontario) but not necessarily direct releases to the lakes.

Sources:

(1)   Lake Michigan Lakewide Management Plan 2000, April, 2000;

(2)   U.S. EPA and EC, PCB Sources & Regulations Background Report, Draft, October 25, 1999.

(3)   U.S. EPA, Deposition of Air Pollutants to the Great Waters – 3rd Report to Congress, 2000, 2000.

(4)   Lake Ontairo Lakewide Management Plan, Stage I: Problem Definition, June 1998.

(5)   Lake Huron Initiative Action Plan, March 2000.

(6)   U.S. EPA, Deposition of Air Pollutants to the Great Waters, 2nd Report to Congress, June 1997, p. 94.

(7)   Great Lakes Commission, 1996 Inventory of Toxic Air Emissions: A Product of the Great Lakes Regional Air Toxic Emissions Project. Part I: Point and Area Sources, December 1999.