For my non-Houston friends- to help you understand the devastation:

[KY_EnviroGuy]

26. Water Level Monitoring

To gain perspective, I've been watching bayou, river and lake levels at these two sites:

A. USGS Flood Event Viewer:
http://stn.wim.usgs.gov/fev/#HarveyAug2017
Notes:
1. Click on "Map Layers", then add "Real-Time Stream Gage". Click on any black triangle to observe the water level graph.
2. Click on "Base Maps" and add "Streets" for a better view.
3. Drag the map where you want, and zoom in and out using (+) and (-).

B. Harris County Flood Warning System:
https://www.harriscountyfws.org/GageDetail/Index/830?span=24%20Hours&v=rainfall
Notes:
1. Click on the "Stream Elevation" tab. You should see a graph showing a profile of that location and current and historic levels.
2. In the two upper selector windows, select the "Agency" and "Location" to observe water levels at a desired point.

Note that from time to time, many of the sensors go out of service due to storm damage, but that is usually noted.

Levels in most of the rivers and lakes are scary-high and rising.