none of them flow year-round, though all have holes in which water may be found during all seasons. Depending on rainfall and temperatures, the creeks generally flow from November to May. After heavy rainfall, the creeks can become impassable, raging torrents, though usually they are not difficult to ford if one does not mind getting wet or (in winter and early spring) cold. The park contains dozens of reservoirs created by the former ranch owners for watering cattle and for recreational fishing and hunting. The largest is Mississippi Lake, at about and long. Other notables are Coit, Kelly, Jackrabbit, and Paradise lakes. Ecology The park protects part of the California interior chaparral and woodlands ecoregion. Large parts of the park are covered in chaparral and oak woodlands. Plant life Besides its size, the park is notable for a mostly intact flora. Unlike many other Bay Area parks, there are no large stands of non-native trees or shrubs. There are forested ridge-tops and slopes interspersed with chaparral and grasslands, with some creeks supporting distinct riparian vegetation. Native trees which dominate the park include valley oak (Quercus lobata), blue oak (Q. douglasii), coast live oak (Q. agrifolia), canyon live oak (Q. chrysolepis), interior live oak (Q. wislizenii), gray pine (Pinus sabiniana), ponderosa pine (P. ponderosa), Pacific madrone (Arbutus menziesii), California laurel (Umbellularia californica), California buckeye (Aesculus californica), white alder (Alnus rhombifolia), California juniper (Juniperus californica), blue elderberry (Sambucus mexicana) and California sycamore (Platanus racemosa). Big-berry Manzanita (Arctostaphylos glauca) reach remarkable size within the park (over 20 feet (6 m) tall) and can grow as either small trees or large shrubs. Other prominent shrubs and wildflowers include chamise (Adenostoma fasciculatum), toyon (Heteromeles arbutifolia), coyote brush (Baccharis pilularis), California sagebrush (Artemisia californica), eastwood manzanita (Arctostaphylos glandulosa), yerba santa (Eriodictyon californicum), buckbrush (Ceanothus cuneatus), California gooseberry (Ribes californicum), fuchsia-flowered gooseberry (Ribes speciosum), yellow mariposa lily (Calochortus luteus) and mountain mahogany (Cercocarpus betuloides). Of the trees, blue oak is the most common and widespread. It is most noticeable in the eastern side of the park, where it often forms pure stands. In other areas it may be dominated by other trees, but if the habitat will support trees, blue oak is usually there. Gray pine is also almost ubiquitous throughout, but curiously, is absent in much of the far southwestern portion, perhaps because of the influence of summer fog, rare elsewhere. Ponderosa pines dominate parts of