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“Alone, we can do so little;

together, we can do so much”

  Helen Keller

THIS WEBSITE IS SUPPORTED by 

Concerned Homeowners  & Businesses of Lake Conroe

AND THE LAKE CONROE ASSOCIATION

SJRA  Studies

The one reference the SJRA gives does not support the conclusion that lowering the dam will benefit those downstream and only discusses hypothetical storms and not the actual effects this decision has had on the communities and businesses.

 

These studies do not exist.

There are no environmental impact studies to support this action.

We need this type of science to determine the impact of lowing the lake on the ecology, fishery, communities, and businesses. 

 

Lake Conroe Dam Gate Operations Modification Analysis April 10, 2018 
Page 11 of 12 6.00 DISCUSSION AND CONCLUSIONS  from the SJRA commissioned report

ref

http://www.sjra.net/wp-content/uploads/2018/05/FNI_Lake-Conroe-Dam-Gate-Operations-Modification-Analysis_20180410.pdf

 

This analysis shows the reduction in normal pool elevation does provide some benefit to areas upstream of Lake Conroe for flood events, and there is also a limited benefit for those downstream as the peak outflow is slightly reduced relative to the base condition. The average change in downstream water surface elevation for a normal pool elevation of 199 ft-msl is a reduction of approximately 1.0 feet for both the 100-year and 500-year storm events. The average change in downstream water surface elevation for a normal pool elevation of 198 ft-msl is a reduction of approximately 1.25 and 1.50 feet for the 100-year and the 500-year storm events, respectively. These reductions are relative to flows that are on average 8 feet above the channel banks in the 100-year event, and more than 12 feet above the channel banks in the 500-year event. As mentioned above, the approximate extents of flooding for the compared scenarios are shown in Exhibit 1 and Exhibit 2, and Water Surface Elevation profiles of the West Fork San Jacinto River between Lake Conroe Dam and Interstate Highway 45 are shown in Exhibit 3.

 

The benefits to those downstream, though the water surfaces are reduced by a foot or more in places, are generally not enough to be considered wholesale improvements to the flood hazard and show minimal differences in spatial extent.

 

For storm events larger than a 500-year event, it is anticipated that the addition of the flood pool will likely yield no additional benefit to the upstream and could potentially increase the flood hazard downstream of the dam if the peak release is delayed such that it occurs at the same time as other tributaries to the West Fork San Jacinto River.

 

For lake levels above elevation 205.00 ft-msl, the gate operations policy is generally dictated by the requirements of the PMF storm, and the peak releases begin to converge to the same discharge rate. The addition of a flood pool below the current normal pool elevation of 201 ft-msl will likely require a change to the gate operations policy, especially as lake levels exceed elevation 201 ft-msl. With the high rate of rise shown in the 100-year and 500-year scenarios, the amount of time prior to when the gates would be overtopped is reduced by approximately 13 hours. An update to the gate operations policy would be needed to ensure appropriate management and technical staff are present whenever the lake level was sufficiently high into the flood pool, but not yet above the 201 ft-msl level for releases, because the lake level will be rising rapidly as the level exceeds 201 ft-msl and rapid gate operations will be required. 

And, the engineering company in it conclusion stated:

"FNI recommends that the analyzed modifications to the gate operations policy for Lake Conroe Dam not be undertaken without: 

•    A thorough study of the impact of the revised policy on lake levels and flows for multiple storm events, up to and including the PMF.

•    A detailed design storm review to make sure that the dam can safely pass the appropriate design storm with the revised policy.

•    A significant initial and ongoing investment to develop additional streamflow gauging stations upstream of Lake Conroe Dam to more accurately quantify inflow into the lake.

 

To our knowledge none of these  studies have been completed so far. Nor has SJRA done any environmental action studies to determine what lowing the water has done to the lake and its environment.