PLANTS HINDER RIVERS, NATURE; TWO SPECIES' REMOVAL URGED.

Byline: Patricia Farrell Aidem Daily News Staff Writer

The pale yellow blossoms of the tamarisk plant are blooming along the Santa Clara River, and bamboo-like arundo is flourishing.

Despite their natural beauty, however, the plants are the enemy, destroying the delicate ecology of Southern California's last wild river.

``They're sucking the water out of the river. They're hurting the native wildlife,'' said Sherry Theresa, executive director of the Center for Lands Management, a nonprofit group seeking to eradicate the two nonnative plants from the Santa Clara.

``These are two exotic plants that really hurt riparian areas to the extent that they no longer function well as rivers. They no longer supply places habitats - and water.''

The center is hoping to contract with The Newhall Land and Farming Co. and to team with the U.S. Forest Service to remove the fast-growing arundo and less common tamarisk from the riverbed. As a condition of ongoing development, Newhall Land is required to help preserve the Santa Clara, which flows from the mountains of Acton to the coast at Oxnard.

``Without question, the flow rates would undoubtedly increase in the river,'' said Cameron Barrows, Southern California regional director for the Center for Land Management. ``Tamarisk and arundo removal will greatly enhance the amount of water on the surface for animals and people.

Arundo is a miniature ornamental bamboo that grows as high as 15 feet. It was brought to the U.S. from Asia in the early part of the century and is noted for its rapid spread.

``You see it in people's yards, and you just cringe,'' Barrows said.

Arundo is tough to remove - a bulldozer will only break apart the root ball and spread nodules that regenerate and establish new plants, he said.

``They grow fast, under harsh conditions,'' Barrows said. ``They become quite a problem because they're not native, so insect-eating birds don't get value out of them because the insects are native and not attracted, and they don't have the right structure for nesting - birds can't use them.''

The plant can be a hazard, drying to create fuel for quick-moving fires and breaking off in heavy rain to create dams so that surrounding neighborhoods flood, Barrows said.

In 1991, arundo created debris dams in the Santa Margarita River in northern San Diego County, causing floods that took out bridges and inundated a military airfield.

Like arundo, tamarisk was introduced in California's rivers as a bank stabilizer and as wind breaks.

And like arundo, it uses far more water than the native plants: the willows and cottonwoods that draw wildlife.

Barrows said that when arundo was removed from a creek near Palm Springs, the water flow ran an extra kilometer before drying up.

``In Palm Springs, when it's removed, the next day there are pools of water,'' Barrows said. ``In a few weeks or months, we've had significant water flowing.''

Each tamarisk plant produces about 500,000 seeds a year, seeds that blow in the wind and establish themselves if they land on moist soil.

What the Center for Land Management proposes is to bulldoze the tamarisk and kill its roots, and to grind down the arundo, then use herbicides to kill off the stumps. The latter method is designed to prevent the spread of the root ball nodules, which would defeat the purpose.

``If you reduce the size, there are no problems with an herbicide getting into the water table or affecting other plants,'' Barrows said.