The California Office of Environmental Health Hazard Assessment has issued a safe eating advisory for any fish caught in the Lake Perris due to elevated levels of mercury and PCBs.

Mule deer, roadrunners, bobcats, coyotes, rabbits, quail, gopher snakes and rattlesnakes may sometimes be seen by day, though they tend to shy away from people.

Conditions are somewhat shadier on hillsides that face north or northwest so that chaparral plants such as chamise, penstemon, and poison oak are found.

Remnants of the original perennial grasses that once flourished in this region can still be found in the flat interior of the park surrounding the lake, but the majority of plants that now make up the valley grassland community (including Russian thistle) were imported from Europe by early settlers.

Riparian areas near springs and seeps, and on east and south lakes include willows, cattails, elderberry and nettles.

Many varieties of waterfowl use the lake including pintails, American wigeons, green-winged teals, mallards, shovelers, various geese, and sometimes tundra swans and pelicans.

As the climate is a warm one, the California Department of Fish and Game make regular plants of rainbow trout throughout the winter months.

The lake records for each of the species are noted here: Largemouth bass, bluegill, rainbow trout, channel catfish, black crappie, redear sunfish tend to be the primary focus of anglers.

Some grasses and wildflowers rush from bloom to seed in just a few short weeks and are able to complete their life cycle within the brief wet season.

Kangaroo rats are so well adapted to dry environments that they seldom drink water, and manage to extract the moisture they need directly from their food.

The plants and animals of Perris Valley have changed considerably over the last two hundred years due to human activity, but its natural history can be intriguing.

The northeast side is largely left undeveloped in order to preserve the natural flora and fauna, although it is accessible to the public.

Coastal fog and smog comes from the west, while "Santa Anas"—strong, hot, dry winds—come from the deserts to the east and northeast.

For several months following July 2005, the water in Lake Perris was drawn down by about 20 percent (about 24 feet) due to safety concerns with the dam.

An extensive modern study concluded that the dam could be partially breached if a 7.5 magnitude or higher earthquake were to strike in the area.

Heightening the engineers' fears was that the San Jacinto Fault, easily capable of creating a 7.5 tremor, passes just a few miles north of the lake.