Lava flows have blocked surface drainages, forming Navajo Lake which drains underground into two watersheds and was later further dammed by humans; another lava-dammed lake downstream from Navajo Lake is now a meadow and Blue Spring Valley also saw the development of lava dams. As a consequence, water on the Markagunt Plateau flows underground through sinkholes developed in limestone rocks, and the burial of surface drainages by highly permeable lava flows likely aided in their development; some sinkholes have formed in basalt and other karstic features are also found in the volcanic field. Many streams and ephemeral creeks head in springs or disappear into sinkholes.