The airport review tested the runway project, not the growth behind it

Sonoma County assumed nearly the same increase in aircraft activity whether the STS runways were extended or not. That allowed the county to study the project's narrower effects, but not whether the project might contribute to the forecast growth.

By Malcolm Crawford

This piece draws on a fuller, sourced brief, published alongside it, which documents every claim below against the Draft and Final Environmental Impact Report and the airport's own public materials. This account reflects the public record as of August 2026.

Airport plans and approvals build on earlier decisions. They can also inherit assumptions and unanswered questions from those decisions. That is why a narrow feature of Sonoma County's 2011 runway review may still matter years later.

Imagine that a county wants to widen a bridge because it forecasts that the number of vehicle trips will double. Its environmental review compares two futures:

• The bridge is widened, and the number of trips doubles.
• The bridge is not widened, and the number of trips still doubles.

That comparison can show the additional effects of the wider bridge itself. But it cannot show whether widening the bridge might help bring about the forecast increase in trips. The increase — and much of its accompanying noise and pollution — has already been included in both futures.

It can also make alternatives intended to reduce the number of trips appear irrelevant. If the doubling is assumed to happen anyway, there may seem little reason to consider public transportation or other measures intended to avoid some of it.

Now suppose that, years later, the county wants to widen the roads on either side of the bridge. Officials point to the earlier review and say that the forecast traffic and its environmental effects have already been studied.

In one limited sense, they have: the review estimated conditions with twice as many trips. But it did not establish that expanding capacity was unrelated to that growth, or compare the forecast with a future involving fewer trips. Treating those questions as settled would ask the bridge review to support a broader conclusion than it reached.

An assumption made for one project would have become the starting point for the next.

That is why Sonoma County's 2011 review of the runway project may still matter years later. The question is not only what the review analyzed for the project approved at the time, but what later airport decisions can legitimately claim it already settled.

Growth with or without the project

The runway project came from an airport master plan that presented proposed development as a way to accommodate forecast demand. The extension was also intended to improve safety and accommodate aircraft capable of serving more distant destinations.

For environmental analysis, however, the county forecast substantially the same total number of aircraft operations whether the project was built or not. An "operation" is one takeoff or one landing.

The review stated that the projected increase by 2030 was "anticipated to occur with or without the proposed project."

This did not make the environmental review meaningless. The comparison could still identify effects caused by the physical runway changes: construction, the locations of runway ends, changes in how aircraft used the airfield, and other differences between the two configurations.

But it meant the review was not designed to determine whether extending the runways might contribute to the forecast increase in aircraft activity. The increase had already been placed in both possible futures.

That is the distinction at the heart of the record:

The review tested the environmental difference between accommodating forecast growth with the runway project and accommodating substantially the same growth without it. It did not test the environmental difference between the forecast growth and a future in which less growth occurred.

The review did account for future noise

There is an important qualification.

The county did not simply ignore the environmental conditions expected with higher aircraft activity. Its cumulative analysis compared future conditions with the 2009 baseline, identified significant noise effects in some areas, and provided for property acquisition and other measures.

So it would be wrong to say that the review never considered the noise associated with future growth.

But that cumulative analysis answered another question: what would total future noise look like if the forecast activity occurred?

It did not separate the portion of that activity that might occur independently from any portion the runway project might help make possible. Nor did it compare the forecast with an alternative designed to produce fewer operations.

The future growth was included in the calculations. Its relationship to the runway project was not tested.

Why a lower-growth alternative disappeared

The distinction became important when commenters asked the county to consider an alternative involving fewer aircraft operations.

County responses repeatedly pointed out that 21 daily commercial departures had already been approved and that the runway project would not increase that number. An alternative based on fewer departures was therefore not treated as a reasonable way of reducing the project's effects.

The reasoning resembled the bridge example: the county treated the forecast activity as independent of the physical project and the 21-departure ceiling as already approved. On that framing, an alternative intended to reduce activity fell outside the question the review had set itself.

That may be a defensible way to define a runway project. But it has a consequence that should be understood clearly. The review cannot then be cited as though it had examined and rejected a lower-growth future on its merits. That was not the comparison it performed.

Why this still matters

As noted at the outset, airport plans and approvals build on earlier decisions. When a new proposal raises questions about growth, noise, capacity, or departure limits, it is tempting to say that the expected growth was already studied in the airport's 2011 environmental review.

But "studied" can mean two different things.

The review used the forecast growth to calculate future noise, emissions, and other environmental conditions. In the comparison between building and not building the runway project, however, that growth was not the question being tested. It was an assumption included in both futures.

For Sonoma County residents, that distinction provides a useful test whenever the 2011 review is invoked in a later airport debate. The question is not simply whether growth appeared somewhere in the analysis. It is what the analysis actually established.

Did it examine whether the project might contribute to that growth, and did it compare the resulting environmental conditions with those of a lower-growth future? Or did it calculate what conditions would be like if the forecast growth occurred?

The 2011 review did the second. The available record does not show that it did the first.

If those other questions were decided somewhere else, that is the record the public should be shown. Being included in an environmental calculation is not the same as being examined as a possible consequence of the project.

Sources

Drawn from How the 2011 airport EIR treated forecast growth in operations, which documents every factual claim above against the Draft and Final Environmental Impact Report and the airport's own public FAQ.

Colophon: researched and drafted in collaboration with Claude (Anthropic).