Tag Archive for: release rates

Pre-Storm Lake- and River-Level Report

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.

Lake Conroe levels for the last week. On May 1, the SJRA increased the release rate from about 350 cfs to 522 cfs. Despite that, the lake has risen back to its normal level because of recent rains.

Here’s a picture of the massive gates at Lake Conroe. Compare them to…

The gates at Lake Conroe can release water at up too 150,000 CFS but are currently releasing at only 522 CFS to avoid flooding downstream areas.

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!

Gates on Lake Houston can release a maximum of 10,000 cubic feet per second, one fifteenth the rate of Lake Conroe.

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.

Trinity River: 

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. 

Navasota River: 

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.

Colorado River: 

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.

Brazos River: 

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.

Please Help

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

SJRA Has Released Water Continuously since December 7

Last night after posting the third flash flood warning in less than a month, several flood-weary people on FaceBook flashed back to Harvey. They questioned why the SJRA wasn’t releasing water in advance of the storm. I quickly went to SJRA.net and looked at their dashboard. They WERE releasing water. The discussion then morphed into another SJRA bloodletting, borne of fear and frustration over a month of near-continuous flood risk and a year and a half of expensive flood repairs.

I’m not here to defend the SJRA. But I suspected perception and reality were currently out of sync. So I emailed a reader’s comments to Jace Houston, general manager of the SJRA, and asked what they were doing to address his concerns.

Update from Jace Houston of SJRA on Recent Releases

Here is the response I got today. I’m reprinting it word for word.

“As you know, there’s a big information gap between what we do during storm events and what the public perceives.  We’re working on some significant items to begin closing that gap.”

“We have an information piece that will go out this afternoon regarding the current rainfall event, but I thought I would mention a couple of items to you just in case you get more inquiries.”

“We’ve been releasing water non-stop since the December 7th rainfall.  It takes quite a while to safely lower the lake after its risen a couple of feet above normal level.  Obviously the level jumped back up from the Christmas rainfall.  Releases went back up to around 7000 cfs, and we’re still at over 3000 cfs.  Rainfall has been in the forecast pretty much constantly the last 30 days, so we’re in the mode of trying to safely move it out of the lake before the next storm hits.”  

“The forecast for this event is not too bad.  Approximately two to three inches across our watershed.  We’re only a few inches over 201’, so we should be able to manage this one similarly to the Christmas event.”

Mark Micheletti emailed this PDF to me last week. Micheletti is one of Kingwood’s two SJRA board members. The letter explains in more detail how they set the level of releases and coordinate with other agencies.

I hope this settles some nerves and reassures people.

Update on Current Conditions and Releases

At approximately 9 p.m. on January 2, the SJRA is releasing 3198 cfs. Harris County’s Flood Warning System shows the largest rainfalls so far during this event are less than 2 inches.

Jeff Lindner of Harris County Flood Control issued this update re: current rains at 7 p.m. tonight:

“A band of heavy rainfall with rainfall rates of 1.0-1.5 inches per hour is moving NNE over much of Harris County currently extending along the US 59 corridor. HCFCD gages show rainfall amounts of .75-1.5 inches with this band in an hour or less and this will likely result in some street flooding. Rises on area watersheds are likely, but creeks and bayous will be able to handle this round of rainfall.”

“Additional activity to the SW will likely move into the county over the next few hours.”

Hope that helps! Stay tuned to the National Weather Service, NOAA or your favorite source of weather information.

Here are the latest predictions from NOAA for the area around US59 and rainfall in the last 24 hours for Harris County.

Posted by Bob Rehak on January 2, 2019

491 Days after Hurricane Harvey