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THIRD INDEPENDENT EXPERT CONCLUDES 241 COMPLETION HAS NO IMPACT ON SURF
Cobbles crucial to surf move downstream during major storm events: Fine sediment has no impact on cobble transport
IRVINE, Calif. (Sept. 11, 2008) – A third independent review of 241 Toll Road studies concludes that claims that there will be potential adverse impacts to the Trestles surf break are not valid. Howard H. Chang, Ph.D., professor of civil and environmental engineering at San Diego State University and a noted consultant with more than 40 years of experience in river sedimentation, conducted the review of studies by Phillip Williams and Associates (PWA) that were commissioned by project opponents.
Chang’s review adds to a growing body of testimony from noted hydrologists, oceanographers, and others, stating that the completion of the 241 Toll Road will not have any impact on the Trestles surfing area or San Mateo Creek.
In July, Richard J. Seymour, Ph.D., research engineer at Scripps Institution of Oceanography and noted consultant in coastal oceanography, conducted a peer review of studies from the opponents to the toll road. “No substantial change, either positive or negative, to surfing quality would result from the project,” Seymour stated in his report.
PWA’s assessments, funded by toll road opponents, suggested that the completion of the toll road might impact the San Mateo Creek watershed by causing more fine sediment to flow through the creek. This fine sediment, according to PWA, would have two impacts: it would decrease the number of cobbles (mid-sized stones) that reach the ocean; and it would alter the fine grained sediment to cobble ratio in the Trestles surfing area.
There is general agreement that both cobbles, and coarse sand and gravel play an important role in the surf break. But Dr. Chang’s review directly questions the PWA assertion that fine sediment would either increase in the creek or have any impact on the surfing area. Among Dr. Chang’s conclusions:
- Since the Orange County Toll Road project will cause no significant changes to the pattern of stream flow at San Mateo Creek, it will have no significant effects on sediment transport in the stream channel.
- The road project will not result in increased fine sediment production and delivery to the creek and the stream mouth. There is no concern that the sub-watersheds crossed by the road project will be de-stabilized. There is no impact of the project on downstream water quality.
- If the creek did experience increase fine sediment, for any reason, it would not impact the movement of cobbles downstream to the ocean. This is because cobble movement occurs primarily during major storm events when the water is flowing so quickly that the stream power far exceeds that required for moving fine sediment. Thus the fines do not affect the transport of cobbles.
- Fine sediment flowing out the creek mouth into the ocean would have no impact on the Trestles surf area. The fact that the beach has coarse sand, gravel and cobble indicates that existing wave action does not permit finer sediments to settle on the beach.
The 241 Toll Road, long a key part of regional transportation plans, has been carefully planned to be constructed in a way that ensures that the world-class surf conditions at Trestles beach will be fully protected. Chief among the false and misleading statements made by project opponents are claims that the surf at Trestles will be “ruined.”
Yet numerous scientists and engineers disagree with this claim. Even Surfer Magazine reported that the change in sediment discharge from the toll road would be minimal: “Spread along the entire beach that is considered immeasurable,” according to the magazine. For details click hear.
Dr. Chang’s report, along with other analyses of the impact of the completion of the road, is available online at: www.RelieveTraffic.org.
ABOUT COMPLETION OF THE 241
Extending the 241 will relieve traffic on Interstate 5 in South Orange County by providing an alternative route. With construction of the toll road, two miles of Interstate 5 will be retrofitted to collect and treat runoff, improving water quality in the Trestles area. Without the toll road, travel from the San Diego/Orange County border to Mission Viejo will take one hour in 2025. With the toll road constructed, the same drive on Interstate 5 will take 25 minutes and it will take 16 minutes on the toll road. The new road will provide an alternative to Interstate 5 for the hundreds of thousands of motorists a day who travel between San Diego, Orange and Los Angeles Counties.
ABOUT TCA
The Toll Roads are operated by the Transportation Corridor Agencies, two joint powers authorities formed by the California state legislature in 1986 to plan, finance, construct, and operate Orange County’s 67-mile public toll road system. More info: www.thetollroads.com
Editor’s Note: Members of the media may contact Dr. Chang for comment: changh@mail.sdsu.edu or (858) 756-9050.
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