My experience: If it is pouring with rain, then your feet will get wet, eventually. But if it is not pouring with rain constantly, then standard gortex lined boots + knee high gaitors will keep your feet dry; especially if you are using an umbrella. I expect my feet to remain dry even when crossing a stream provided the water is not deepeer than the boot. And I can often cross a stream up to half calf high with dry feet provided the stream is not too wide and I move fast. The umbrella is particularly usful in prventing water running down ones legs and into the boots.
If you are looking at low boots, then maybe you should also be looking at a gaitor which fits tightly over the boot to prevent ingress of mud and water.
Kea