Engineers Say New River Mining Would Speed Coast Erosion

If two companies win approval to step up mining of rock and sand from the Santa Clara River bed, it would speed erosion at Ventura County beaches about 25 miles downstream and increase the threat of flood damage to the county’s beachfront houses, coastal engineers warn.

The proposals, by Sespe Rock Products Inc. and Granite Construction Co., call for the removal of nearly 1 million tons of additional material from the riverbed each year.

Seven companies now hold 10 permits to mine a combined total of 1.9 million tons of rock and sand each year from the riverbed.

If the Board of Supervisors approves the two proposals for additional mining, a decision expected this year, the total amount of sand and rock that could be taken from the river would increase to almost 3 million tons annually.

e environmental consequences of increasing the river’s annual yield by nearly one-third will be revealed later this month when the first draft of the county’s environmental impact report is complete. After an internal review and revisions, county officials will release the document for public comment, probably late this spring.

Mining, along with dams upstream that block the sand’s path toward the sea, combine to reduce the amount of sand that reaches the beach by 75% from historical levels, according to a 1989 study performed for the Beach Erosion Authority for Control Operations and Nourishment. The public agency, known as Beacon, monitors beach erosion.

Santa Clara River sand replenishes what ocean tides wear away at the shoreline from McGrath State Beach to Point Mugu.

“Sometime after the year 2000, there will be a significant impact at the beaches,” said James A. Bailard, a technical adviser to Beacon and a coastal engineer and oceanographer. “The primary question is when will that impact occur.”

James P. Sandoval, president of Sespe Rock Products, said the need for the material, which forms the foundation for every road, building and bridge in the county, outweighs the risk of future beach erosion.

In addition, he said, the excavation operations benefit nearby farmers and cities.

“When we dig out the channel, it helps prevent damage to them during a 100-year flood,” Sandoval said. He pointed out that the river bed was designated by the county in 1975 as an area set aside for mining.

Under the expansion proposal, Sespe, whose huge rock crusher in the Sespe Creek bed now marks the entrance to Fillmore from the west, would move its operation into the Santa Clara River and out of view from the road. The company wants to mine more than 7 million tons from the new location during 15 years.

Under Granite Construction’s proposal, it would build a new plant and expand present operations east of Santa Paula for a total of 7.7 million tons over 20 years.

Other major mining operations in the river include those run by SP Milling, Cal-Mat Co. and the Regional Sanitation District.

The environmental report on the new proposals will study beach erosion, traffic, dust and ground water disruptions. In addition, the report will examine the effect that expanded operations would have on the birds and fish that thrive in the dry riverbed and its pools, said Judith Ward, the county planner who is in charge of the project.

Ward said neighbors in the area, who have already begun to complain about the additional traffic the project would bring, also object to the disruption to wildlife.

“There are egrets and other birds and butterflies and animals that live in the river bottom, so the neighbors are used to seeing it as a really tranquil setting,” she said.

Representatives of the state Department of Fish and Game also have objected to mining projects on the river because they disrupt the river habitat.

In addition, the county flood control division will examine the proposals to ensure that the mining would not erode bridge foundations or bring the river bottom below the “red line,” said Gerald J. Nowak, deputy director of the division. The red line is the level at which the river bottom would lie without disruption from man.

“We are concerned about erosion of the structures in the river as well as oil and pipe lines,” he said.

Sandoval said his proposal to mine a new site does not necessarily represent additional extractions, since he plans to abandon his existing location on the Sespe Creek near its confluence with the Santa Clara.

He said he has mined all the material from that location and no storms have come in recent years to bring more sand down from the mountains at the headwaters of the Santa Clara.

“We’re anxious to get down here,” he said, standing in the dry riverbed with the hills in the South Mountain range at his back. “There is a lot of material down here to mine and the county really needs it.”

But Ward said it is uncertain whether the county needs the material.

“We don’t have a lot of construction going on now in Ventura County,” she said. “So will the material end up being used to widen Highway 126, or will it be used to build houses in Valencia?” She said the supervisors will look closely at that question, which will also be addressed in the environmental study.

The sand deficit has not begun to show on area beaches, despite four decades of dams and intensive excavation, said oceanographer Bailard.

“The reason is that the delta at the mouth of the Santa Clara has made up the deficit,” he said. The delta formed after floods in 1969 brought huge deposits of rock and sand down the river. It has helped stabilize beaches that are down the coast from the river mouth near McGrath State Beach, he said.

“But we don’t really know how long it will last or when it will run out of sand,” he said.

“You have a classic case of competing priorities here,” Bailard said. “There is clearly a need for sand mining and construction materials, so what’s more important? That’s what the supervisors will decide.”