Final answer:
Mary likely cannot take a casualty loss for the decline in value of her residence caused by the fire, as the tax law typically requires physical damage to the property for such a deduction.
Step-by-step explanation:
Under United States tax law, a casualty loss can typically be deducted if it results from a sudden, unexpected event such as a natural disaster. However, for the deduction to be applicable, there must be a physical damage to the property. In the case of Mary, although her property's value has decreased due to the forest fire, there has been no physical damage to her residence.
Therefore, it is unlikely that Mary would be able to claim a casualty loss deduction for the mere decline in property value caused by the environmental impact of the forest fire.
During the economic recession, impacts on property values were noted due to various factors such as the mortgage crisis and decreased tax revenues, but not all these situations qualified for a casualty loss deduction.
Similarly, in other historical cases of property value decline due to environmental changes or disasters, unless the property itself suffered physical damage, a casualty deduction was generally not permitted under tax law.