With major rainfall expected this week, here is a pre-storm report on lake and river levels.
Lake Conroe Pre-Storm
Even though Lake Conroe has released water continuously since April 1, the SJRA has not succeeded in reducing the lake level to their seasonal target of 200 feet. They were close at one point, but recent rains have elevated the lake back to its normal pool level. As of this writing, the lake is at 200.87 feet. Normal level is 201 mean feet above sea level. Thus Lake Conroe is only down about one tenth of an inch despite the fact that the SJRA continues to release water at the rate of 522 cubic feet per second.
Here’s a picture of the massive gates at Lake Conroe. Compare them to…
Lake Houston Pre-Storm
Lake Houston has its gates wide open. At that setting, they can release 10,000 CFS. But the recent rains are also refilling Lake Houston as fast as its draining. Normal pool level is 42.5 feet and the lake is presently. at 42.6 feet. This is why we need more gates!
To summarize, both Lake Conroe and Lake Houston are within a tenth of an inch of normal levels. Both are releasing water. Lake Houston is releasing water as fast as it can. Lake Conroe cannot release any faster without flooding the Humble/Kingwood area, especially with more rain on the way.
Additional rainfall tomorrow should saturate the ground. More storms later in the week could cause river flooding. Harris County Flood Control expects heavy rain for the next 5-7 days.
Pre-Storm River Report
With rivers already highly elevated and some at or above flood stage, additional widespread heavy rainfall will only aggravate ongoing flooding or result in worsening flooding especially along the Trinity and Brazos basins.
San Jacinto River:
No flooding is currently impacting the basin, but forecasts for this week indicate significant rainfall potential over the basin. If accurate, the rainfall would result in significant rises on the system.
Flooding is in progress both upstream of Lake Livingston and downstream of the lake in Liberty County. Flooding will continue through the end of the week and likely into next week. Liberty may approach major flood levels by the end of the week depending on releases from Lake Livingston.
Minor flooding is in progress as upstream releases from Lake Limestone are maintained. River is in recession and may fall back below flood stage by the middle of the week.
Upstream weekend flood wave is moving downstream and is at Columbus and will near approaching Wharton in the next 24-36 hours. No flooding is currently expected on the Colorado basin.
Flood wave is passing Bryan and heading for Hempstead. Minor flooding is forecasted for Richmond and moderate flooding at Rosharon. These three charts tell the story.
Brazos River at Hempstead:
Brazos River at Richmond:
Brazos River at Rosharon:
Unlike street flooding which is fast and local, river flooding is delayed and regional. As you can see from these charts, it can take days for upstream rains to create downstream floods.
Rains later this week could be intense. Some forecasters are predicting up to 10 inches. Make sure the storm drains on your street are clear. If you can’t remove accumulated debris yourself, please call 3-1-1. The last thing we need is for all the downed tree branches, twigs, and leaf litter from last week to clog drains with 10 more inches on the way.
Posted by Bob Rehak on 5/6/2019
615 Days since Hurricane Harvey