Beginning at the southwest corner of township one hundred forty-one north, range ninety west of the fifth principal meridian, a point on the tenth standard parallel; thence east along the tenth standard parallel to the southeast corner of township one hundred forty-one north, range eighty-eight west; thence north along the line between ranges eighty-seven and eighty-eight west to the northeast corner of township one hundred forty-three north, range eighty-eight west; thence east along the line between townships one hundred forty-three and one hundred forty-four north to the line between ranges eighty-three and eighty-four west; thence north along the line between ranges eighty-three and eighty-four west to the main channel of the Missouri River; thence in a general northwesterly direction along the main channel of the Missouri River to a point where the line between ranges ninety and ninety-one west intersects the main channel of the Missouri River; thence south along the line between ranges ninety and ninety-one west to the southwest corner of township one hundred forty-five north, range ninety west, a point on the eleventh standard parallel; thence east along the eleventh standard parallel to the northwest corner of township one hundred forty-four north, range ninety west; thence continuing south along the line between ranges ninety and ninety-one west to the point of beginning.