Valuing Land vs Improvements for Depreciation

[Nathan Maier]

I purchased a property in California last year for $1,770,000. My supplemental taxes list the "land" value as $1,300,000 (73.5%) and the "improvements" as $470,000 (26.5%). Very round numbers, like the assessor didn't even try. The previous year was $840,942 (65%) land and $446,750 (35%) improvements.

Obviously I want the "improvements" value to be as high as possible for depreciation. 26.5% seems incredibly low. That is well below replacement cost and I don't believe the lot to be worth anywhere near $1.3MM. I've always been told to use property tax numbers on land vs improvements for depreciation, but do I have to? Can I dispute this somehow?