X0203 3 2011-02-14 0 0000086264 ST LAWRENCE SEAWAY CORP STLS 0001225207 LEIDEL PETER A 410 PARK AVENUE, 19TH FLOOR NEW YORK NY 10022 1 0 0 0 Common Stock 17938309 I Through Yorktown Energy Partners V, L.P. Common Stock 17938309 I Through Yorktown Energy Partners VI, L.P. These securities are directly owned by Yorktown Energy Partners V, L.P. Mr. Leidel is a member and a manager of the general partner of Yorktown Energy Partners V, L.P. Mr. Leidel disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein, and the inclusion of these shares in this report shall not be deemed an admisssion of beneficial ownership of all the reported shares for Section 16 for for any other purpose. These securities are directly owned by Yorktown Energy Partners VI, L.P. Mr. Leidel is a member and a manager of the general partner of Yorktown Energy Partners VI, L.P. Mr. Leidel disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein, and the inclusion of these shares in this report shall not be deemed an admisssion of beneficial ownership of all the reported shares for Section 16 for for any other purpose. /s/ Peter A. Leidel 2011-04-01