Love ’em or hate ’em, those rows of tall eucalyptus trees on the Nipomo Mesa do serve one useful purpose: to slow the sometimes stiff winds coming off the ocean. Whether they were planted for that purpose, those trees are effective windbreaks.
Strong winds also stir up sand on the Oceano Dunes and cause episodes of high fine particulate matter, or PM10, on the Mesa. The second phase of an ongoing study conducted by the Air Pollution Control District examined whether vehicle activity had any impact.
One conclusion of that study was that vehicles riding on the Dunes caused the sand to move at lower wind speeds than in a nonriding area. The presumption was that vehicles disturbed the sand enough that it was easier for wind to move the sand.
To arrive at this finding, the study measured amounts of sand that moved at a given wind speed in the riding area. A major criticism of the study was the choice of where to measure wind speeds for that riding area.
Instead of setting up a wind monitoring station on the Dunes, the location chosen was the Cal Fire fire station along Highway 1, which is 1.5 miles away from the nearest sand dunes. The problem with this location is trees. The fire station is shielded from the wind by several rows of eucalyptus trees, which makes measuring Dunes wind-speeds by the Cal Fire station problematic.
Until recently, we did not know how bad the choice of the Cal Fire station was. With additional wind data available, we now know that wind speeds at the riding area on the Dunes are substantially higher than at the Cal Fire station. Both State Parks and the Desert Research Institute have measured wind speeds at three sites on the Dunes, and those speeds are 70 percent higher than at the Cal Fire site. Two of those sites are near where some of the sand measurements were taken. The wind speeds are high enough that the conclusion in the study claiming that vehicle activity caused the sand to move easier is no longer valid.
The study did not even consider that the trees at the Cal Fire site might result in lower wind speeds, yet one obligation scientists have is to identify any shortcomings in the methods used to obtain data.
Besides wind speeds, there are other flaws in the study that the city of Pismo Beach cited in a letter to the APCD board, which requested that these flaws be corrected before any action is taken on proposed rule making.
If the board adopts the rules as written, there will likely be legal challenges by numerous parties, which could lead to protracted litigation with an uncertain outcome. Public money spent on litigation could well be used for other purposes.
A better choice is to adopt a rule that requires best management practices in the operation of the park. State Parks stated they support this approach, and it would immediately lead to a collaborative effort to find ways to reduce PM10. This collaborative effort could also address some of the flaws in the Phase 2 Study so we can have a better understanding of the particulate problem. With that knowledge, we can devise strategies to reduce PM10 and to protect public health.
Ed Waage is a Pismo Beach City Council member who represents the city on the APCD board.