The original article is about the unincorporated community Mendocino. It's population is about 1000.

Mendocino county is almost 4000 square miles (more than 10,000 square kilometers). Other parts of Mendocino County have substantial agriculture.

The links provided are about the county not the community.

Could perhaps most of 4000 square miles of the county being filled by water intensive farming have some connection to town located in that county at the edge of ocean being dry?

Not really, the community of Mendocino is in a different watershed. Per the article, it relies on shallow aquifers.

You can look at on Google maps. The agricultural areas are along the 101 and further east. Even those areas aren't involved in the California Canal politics, They're still in a different watershed.