Iowa Great Lakes, Storm Lake and Clear Lake walleye length limit changes effective January 1, Iowa Department of Natural Resources (DNR) is changing the protected walleye slot limit to. e. Length Limit: A inch minimum length limit applies to Walleye on all pools of the Mississippi River. The DNR is proposing a inch minimum length limit on all walleye captured from Rathbun Lake. No more than one walleye greater than 20 inches in length may be taken per day. The protected slot limit. [HOST] › About DNR › DNR News Releases. The daily bag limit will be three walleyes with one walleye over 25 inches. The protected slot limit on walleyes is 19 to 25 inches, with only one walleye over 25 inches allowed per day. The daily bag limit shall be three, with a possession limit of six. Until the end of December, the current 17 inch to 22 slot size limit. Officials with the Iowa Department of Natural Resources say the protected walleye slot limit will change from 19 to 25 inches on Big Spirit Lake. The Iowa Department of Natural Resources announced changes to the walleye slot limit at Storm Lake that will take effect on Jan. These changes will start January 1, All. 1, On Jan. . 1, this changes to a slot limit of 19 to 25 inches at Big Spirit, East and West Okoboji, Upper Gar, Minnewashta, Lower Gar and. In addition, you must immediately release alive all.