TULSA, Okla. (AP) - The U.S. Army Corps of Engineers has lifted all blue green algae closures, warnings and advisories at Fort Gibson and Skiatook lakes in northeastern Oklahoma.

The Corp's Tulsa District said Friday it collected water samples at Fort Gibson Lake on Sept. 27 and at Skiatook on Sept. 23. An analysis showed that the blue-green algae levels had dropped below the advisory level at both lakes.

The Corps says it has also changed the blue green algae warning at Sandy Bass Bay and Porum Landing at Eufaula Lake to an advisory. Water contact in those areas is discouraged.

The Porum Landing swim beach was closed due to algae levels there. Although the algae levels have improved, the beach will remain closed due to the end of the normal recreational season.