Unequitable HOA assessment

I own 2 lots and pay double annual assessment fees. In most cases this would be fair because a double lot requires double services. However one of the lots is unique in that it does not receive any services from the HOA. There are no common use spaces in the association like parks, pools etc. 39 out of 40 lots in the association are on a waterfront canal in which the HOA maintains the bulkhead and canal, half of the lots are on a private road maintained by the HOA and half are on a county road.

Both of my lots are on the county road thus both the road and culverts are maintained by the county. One lot is on the canal front and the other is the only lot in the entire association that is not on the canal and specifically excluded in the deed restrictions from use of the canal. This lot receives absolutely no maintenance services from the HOA where every other lot receives bulkhead maintenance and some private road maintenance. Thus for my combined lots I am paying double assessment fees but receiving services from the HOA equal to or less than all the other single lot owners. Can the HOA continue to charge me to subsidize the bulkhead repair/maintenance and road maintenance on all the other HOA properties when the property assessed does not receive any of these services and is specifically excluded from their use?

Tim's answer is spot on. Most HOA governing documents specify that all lots are assessed equally, but yours could be different. The CCRs are essentially a contract between all owners that runs with the land, so you agreed to the contract by buying the property.

Many condo associations do vary the dues by unit, most often by square footage, but your situation doesn't sound like a condo.