What is the location of the river mile that is larger than 938.9, and Olmsted Locks and Dam?
CREATE TABLE "downstream_pittsburgh_to_olmsted" (
  "locks_dam" text,
  "location_l" text,
  "river_mile" real,
  "lock_side" text,
  "lock_lift_drop_in_feet" text,
  "pool_length_miles" text
);
SELECT "location_l" FROM "downstream_pittsburgh_to_olmsted" WHERE "river_mile">938.9 AND "locks_dam"='olmsted locks and dam';