SRJA Begins Seasonal Lowering of Lake Conroe to Provide Buffer Against Flooding

On April 1, The San Jacinto River Authority (SJRA) began releasing water from Lake Conroe at a slow, controlled rate to help guard against flooding this spring. This is the first of two seasonal lowering periods scheduled this year.

Details of Lowering Policy

  • From April 1 to May 31, SJRA will lower Lake Conroe one foot from 201 to 200 msl (mean feet above sea level).
  • During the peak of hurricane season, from August 1 to September 30th, SJRA will lower the lake two feet to 199 msl.

If the lake level has already dropped to the target elevation due to evaporation, no additional releases would be made.

If a storm enters the forecast while seasonal releases are being made, releases would be stopped until rainfall is out of the forecast to avoid overloading the downstream watershed.

For the complete text of the SJRA’s seasonal lowering policy, click here.

Rationale for Seasonal Lowering

Yesterday, SJRA began releasing water at the rate of about 375 cubic feet per second (cfs). This rate is slow enough that it will not flood downstream communities, yet fast enough that, over time, it will give Lake Conroe extra capacity to absorb heavy, spring rains.

On April 1, the SJRA began lowering the level of Lake Conroe by 345 cubic feet per second.

“We should not forget that the Tax Day and Memorial Day floods both happened in the spring,” said Chuck Gilman, SJR’s Director of Water Resources and Flood Management.

Gilman emphasized that the seasonal lowering strategy is temporary while downstream communities address their own flood mitigation strategies such as dredging and additional gates for Lake Houston. Dredging will help restore conveyance of the San Jacinto river. Gates will increase the release rate of Lake Houston. Increasing the release rate is important for two main reasons:

  • The gates on Lake Houston have one fifteenth the release rate of Lake Conroe’s, creating a bottleneck – 150,000 cfs for Lake Conroe; 10,000 cfs for Lake Houston.
  • Pre-releasing water from Lake Houston in advance of a storm can take days. A storm can easily veer away during that time, resulting in wasted water. The long lead time significantly raises the level of that risk. More gates will enable the Coastal Water Authority to release water faster and reduce that risk.
Gates on the Lake Conroe Dam can release water 15X faster than the small gates on Lake Houston’s Dam.

Pressure Mounting on Board as Board Changes

During last February’s SJRA board meeting, the board voted to continue the lowering policy, which it began in 2018. However, lowering Lake Conroe has encountered pushback from boat owners who complain about the inconvenience. Board member Brenda Cooper voted against the lowering. All other board members who were present voted to continue it.

However, the board has seven directors and the terms of three will expire this year. As pressure mounts on the board and board members change, the seasonal lowering policy could be in jeopardy.

Mitigation Projects Also Pressured

All the more reason to dredge the mouth bar on the West Fork NOW! By the time Phase 1 is completed, it will have taken 15 months. But six months of that was surveying, bidding, and mobilizing the job. If FEMA and the Corps authorized dredging the mouth bar today, it could be completed before next spring. That would reduce the need to lower Lake Conroe again next year.

Stephen Costello, the City of Houston’s Chief Recovery Officer, speaking at a Kingwood Town Hall Meeting on March 21, said it could take 3 years to add 10 additional gates to Lake Houston. That was the best case. Others have previously estimated it could take 10 years.

It’s unlikely that residents of Lake Conroe would tolerate seasonal lowering of their lake for 3 more years, let alone ten. The longer flood mitigation takes, the more pushback we can expect. That’s yet another reason why we need to accelerate mitigation projects.

Posted by Bob Rehak on 4/2/2019

581 Days since Hurricane Harvey