Here's some general information on Burn Permits. The process is far more confusing than it should be but it is what it is. This is my personal understanding of the system and how it works.
There are three agencies that deal with Burn Permits. Mendocino County Air Quality Management District (MCAQMD often just called Air Quality and hereafter abbreviated as AQ) is the main controlling agency but Cal Fire also writes permits independently of AQ. Many local government fire departments, Anderson Valley (AVFD) among them, write permits for AQ. AQ permits may be obtained directly from them on line for which they charge $17. In Anderson Valley, we provide the same permit at no charge to our residents. All local government fire departments may only write permits for properties within their district boundaries.
There are three seasons. Here’s where it really gets complicated. There are three periods during the year that have different rules concerning what and when you can burn. “Winter Burning Season,” “Fire Season” and the period when the “Burn Ban” is in effect. Winter Burning Season is the period which starts at the close of Fire Season (sometime in the fall after we have received two inches of rain with more in the forecast) and continues through to the opening of Fire Season (usually May 1st). The Burn Ban is a period within the Fire Season during which no outdoor burning is allowed. All of these periods are subject to fire and weather conditions in any particular year.
Fire Season — During Fire Season you must have a permit from Cal Fire even if you already have an AQ permit. During Fire Season Cal Fire’s rules preempt AQ’s rules and are far more restrictive. Basically, in most cases, under a Cal Fire permit you are restricted to only burning piles “4x4 and smaller,” More flexible permits can, under some circumstances, be obtained from Cal Fire but they require a site visit for inspection, and are more difficult to obtain.
Winter Burning Season — During Winter Burning Season, AQ rules apply. AQ permits obtained directly from AVFD are somewhat more flexible than the standard AQ permit. The specific rules are more complicated than time and space allow here. They will be explained in detail when you receive you permit and it is your responsibility to know and follow them.
The Burn Ban — The Burn Ban is entirely dictated by Cal Fire and establishes a period when no outdoor burning is allowed. Anyone burning during this period is subject to punitive action. The burn ban generally starts a month or more after the opening of Fire Season and is instituted by Cal Fire when they feel the risk of fires escaping is too great to allow any outdoor burning. All permits are suspended during the Burn Ban regardless of who writes them and it is the permit holder’s responsibility to know if the Burn Ban is in effect. You can get this information by calling your local Cal Fire Station or the Unit Headquarters at 459-7414.
There are several other conditions on all types of Burn Permits and you should be sure you understand them all before you start burning. Everyone should also understand that a “permissive burn day” means that air quality conditions are favorable. It does not mean that it is safe to burn. Windy days are good for air quality but can be very problematic for fire safety. It is the permit holder’s responsibility to insure that all conditions will be safe not only when the fire is ignited but for the entire time it is likely to burn. It is your responsibility to make sure your fire and smoke do not impact your neighbors. A good practice is to ignite a small fire and watch what the smoke does. If it’s blowing towards neighboring homes that are close enough to be impacted, wait for more favorable condition to ignite your other piles in the area. It is also your responsibility to make sure your fire does not escape. If either of these things happen, you may be cited and fined
To sum up, here's what I recommend. Get your free MCAQMD permit through AVFD, if you are a resident of our district, after Cal Fire announces the close of Fire Season. You will need to estimate the number of piles and their size. In my opinion it's best to overestimate rather than underestimate. If you have a problem and Air Quality comes out, having your permit underwritten could be a problem causing you to be cited and possibly fined.
Here are some guidelines to help you estimate tonnage. A ton of brush is approximately 400 cubic feet (per AQ) which roughly translates to a pile about 12 feet in diameter and about six feet high. The maximum you can burn without triggering the requirements for a "Smoke Management Plan" (SMP) is 50 tons. There are other triggers for a SMP such as not having a pile burn longer than 24 hours but again, some latitude is afforded to local fire agencies like AVFD on this requirement. It is generally recognized here that in some cases larger piles may be necessary and that these piles may exceed the 24 hour rule BUT in all cases it is your responsibility to get the local weather forecast and make sure your fire will not still be burning when unsafe conditions develop such as windy conditions.
Be mindful of the fact that some of these rules and conditions are somewhat flexible depending on who's doing the interpretation and enforcement. Follow the basic rules; don't have an escape, don't smoke out your neighbor, read and follow the conditions of your permit and you shouldn't have a problem.