In Glen Canyon Park, about 20 mature eucalyptus trees were removed in 2004 as part of an effort to increase the diversity of species living along Islais Creek. The plan envisions the removal of an additional 120 trees (of the total of 6000 trees in the park) to further improve the creek, to increase the extent of the park's grasslands, and to promote forest understory plants. The plan also seeks to restore some open-water areas along the creek, which is nearly totally obscured by the willow thickets. The change in the creek would be established both by re-planting sections of the creek's banks with different plants and by the introduction of "scouring" structures.