Tag Archive for: Public Works.

Recommended Floodgates Could Release at Rate of Lake Conroe During Harvey

City of Houston Mayor Pro Tem Dave Martin’s office has supplied ReduceFlooding.com with the Black & Veatch Engineering report on the recommended alternative for adding floodgates to Lake Houston. One key finding immediately jumped out at me that wasn’t in Martin’s press release last week. The recommended gates would have a release capacity that virtually equals the highest release rate of Lake Conroe during Hurricane Harvey.

The Lake Conroe release rate during Harvey maxed out at 79,000 cubic feet per second (CFS).

The eleven tainter gates recommended by Black & Veatch would have a release rate of 78,700 CFS.

New Possibilities, More Certainty

That opens up a world of possibilities. For instance, the City could wait to start releasing water until it knew water was coming downstream from Harvey.

Said Martin, “Once constructed, we can release with a moments notice which gives us great opportunities to coordinate release protocols with the SJRA!!”

Previously, Public Works has been reluctant to release water in advance of a storm because the release rate of the existing gates is so small. They have to start lowering the lake so far in advance of storms that a storm can veer away before it gets here. If it does, that means water has been wasted.

The recommended floodgates should provide much more certainty for operators and avoid waste.

Key Elements of Recommendation

site of proposed gates for Lake Houston on east side of dam
Gates would be placed at the original channel for the San Jacinto River seen in foreground.

Other key elements of the recommendation include:

  • Locating the floodgates in the earthen eastern portion of the dam near the old channel of the San Jacinto River.
  • Creating baffles and a dissipation basin downstream from the new gates to break up the flow and reduce water velocity
  • “Outdenting” the gates (i.e., building them in front of the current dam)
  • A bridge between the two parts of the earthen dam
  • Using tainter gates, the same type used at Lake Conroe.
  • A 3.5 year construction schedule.

The last point means that if construction started in January, the earliest completion date would be mid-2026.

However, given the need to line up additional funding in the state legislature, 2027 is a more realistic date.

For a complete discussion of the project history, constraints, alternatives, recommended options, construction drawings, rationales, and costs, see the entire 28-page Black and Veatch Report by Chris Mueller, PhD, P.E.

Posted by Bob Rehak on 12/14/22 based on the Black & Veatch Report

1933 Days since Hurricane Harvey

Lake Houston Property Owners Should Prepare for Lower Lake Levels (or Not)

Note: I posted this this morning before a surprise storm dumped up to 10 inches of rain on the Lake Houston Area this afternoon. Now the river is expected to flood … despite the pre-release. At 7PM on Tuesday, the floodgates on Lake Houston remain wide open. As the river rises past flood stage, any thoughts of being land locked are now moot.

Houston City Council Member Dave Martin issued a press release this morning warning Lake Houston property owners to prepare for lower lake levels. Houston Public Works and the Coastal Water Authority are monitoring forecasts calling for substantial rainfall over the next several days.

Lower Lake Levels Heading Lower

Lake Houston is currently at  42.11 feet and still receiving water from weekend storms. But that’s a half inch down in the last 12 hours.

Lake Houston has a normal pool elevation of 42.5 feet. All four gates on the existing dam structure are open and will remain open with a goal of lowering the lake to 41.5 feet before the next round of rainfall. Property owners are encouraged to secure property along the shoreline. 

Lake-Lowering Policy

Lake Houston is lowered if the National Weather Service predicts greater than 3 inches of rain within a 48-hour period. To monitor Lake Houston and the forecasted rain, click here

6-day precipitation forecast: 7 inches across the Houston Metro Area

Posted by Bob Rehak on 5/7/2019

616 Days since Hurricane Harvey