PARENTING : The Life of a Creek

Dozens of creeks burble through the Santa Monica Mountains. A few have remained pristine. But most major creeks have suffered the intrusion of man, be it from housing developments or, in the case of Malibu Creek, a sewage treatment plant.

Topanga Creek, which runs from mountain ridges to the Pacific Ocean, is by no means pure. Houses dot its banks. Septic tanks leak into the water. But this creek persists, to some extent, in its natural state. Fifty-nine species of animals make their home in the surrounding canyon. Most of the native plants have survived man’s intrusion.

Pollution could change that. Developments, such as a golf course, are frequently proposed for the area.

So Topanga Creek hangs in a balance. It serves as an important example, biologists say. Will Southern Californians protect and restore their dwindling wilderness? Or will they let places like Topanga Creek be overrun?

Here is a primer, a glimpse of life along the creek and the dangers this life faces. Read it with your children.

1. Acres of chaparral blanket the northern rim of Topanga Canyon. Rains fall on this slope, feeding stands of oak and willow trees. Streams form and join to become the creek. This is the starting point for miles of plant and animal life down the canyon.

2. Riparian foliage covers the banks of the creek. Sycamore and oak trees flourish here, and opuntia cactus sprouts from nearby rock formations. These plants are native to the area, helping each other thrive and providing food and shelter for all sorts of insects and animals.

3. Frogs hop along muddy banks. Snakes slither through the rocks. Rabbits and gray squirrels and coyotes live in the woods and fields and drink from the creek. High above, red-tailed hawks circle. They, too, are part of Topanga Creek’s natural balance.

4. A wooded canyon can be a beautiful place to live. But building a house among wildlife can upset the natural balance. Trees may be cut down. Bulldozers leave fresh dirt that can clog the creek and increase the chances of flooding. Foreign plants brought in to beautify a yard can spread to surrounding areas and force out native vegetation.

5. After a house is finished, the people who move in may continue to alter the natural balance. Rain washes motor oil off driveways and into the creek. Lawn fertilizers also run off, causing algae to bloom underwater. Excess algae uses up oxygen and may suffocate both plants and animals. Septic systems need to be well-maintained.

6. Sean Manion, a Santa Monica Mountains ecologist, explains that places like Topanga Creek need to be protected not only for plants and animals but for the future of humans. The Earth, he says, is “an interwoven fabric of life. All strands are interconnected and dependent on one another for the well-being of the whole planet. When habitats and species are destroyed or degraded, life’s fabric begins to unravel.”