Earlier quoted context omitted.
By what measure? If you don't know how to recognize when it's become a problem then it's not meaningful when you say you don't see a problem. What is straining to you? I would describe our education system, our legal system, our prison system and our welfare system as all being currently "strained" so we must have different definitions. (and to the downvoting crew, feel free to explain to me what productive disagreee…
I don't think the strain on any of those things is caused by immigration. If we improved them to make them better for current residents, it would also increase our capacity for immigrants. But I'd see that as just a side effect of fixing broken systems.
You've also made the mistake of thinking that just because you've found one problem that others must not exist. We can have broken systems and problems caused by immagration.
10% ESL students in our public education system should qualify as a strain. 17% of California's prisoners being born abroad should qualify as a strain. Are these numbers not high enough for you? If not, what does too high look like to you?