Image of Building 60 at the Naval Station in Alameda where radioactive dirt and other potential contaminants were discovered back in 2008.

Contaminated Property

On November 3, 1998, the voters of California approved Proposition 1. This constitutional amendment allows one of two forms of property tax relief for qualified contaminated property.
Property owners may choose from either of the following relief:


Base Year Value Transfer

Subject to certain conditions and limitations, contaminated property may be sold and its base year value transferred to a replacement property of “equal or lesser value”. Both the original property and the replacement property must be located in Alameda County. The replacement property must be acquired or newly constructed within five (5) years after the sale or transfer of the qualified contaminated property. A timely claim must be filed within three (3) years after the replacement property is acquired or newly constructed.

To download the Claim for Transfer of Base Year Value from Qualified Contaminated Property to Replacement Property, click here (PDF) or go to Forms.

New Construction Exclusion

If structures located on the qualified contaminated property are substantially damaged or destroyed in the course of the remediation of environmental problems, the repair or replacement of such structures may be excluded from the definition of “new construction” provided that the repaired or replacement structure is similar in size, utility, and function to the original structure. An owner must notify the Assessor prior to, or within 30 days of, the completion of the construction project that he or she intends to claim this exclusion.

For more information about qualifying for relief as described above, click here (PDF) to read the Board of Equalization’s letter to County Assessors (LTA 2007/047). For more information please call 272-3787.

Attention!Public Counter Closure

Due to the Covid-19 pandemic and public health concerns, the Assessor's Office is temporarily closing our public counters until further notice for both your and our staff's protection. It is important that we eliminate personal contact whenever possible to fight the spread of the virus. Our technicians are still available to provide assistance via telephone from 8:30AM-5:00PM Monday through Friday.

If you need to drop-off documents, please leave them in the box provided and staff will retrieve them promptly to protect confidentiality.

We sincerely appreciate your understanding and patience during this most difficult time.