Dickinson bayou, tidal flow rate, gum bayou, and drainage
Once the pumps are installed Bayridge, gum bayou opened up, water gets to Dickinson bayou, what next? With another event such as Harvey, once you get water to Dickinson bayou, with said improvements, minus no improvements to tidal movements of Dickinson bayou, will there be any overall change? My guess is that this will be a very costly experiment, when previous studies has shown that DICKINSON BAYOU NEEDS TO BE DREDGED AND CLEANED OUT. Imo, you need to drain straight to bay via 96 and 646, improve existing drainage to correct the back flow from bay...
DICKINSON BAYOU WATERSHED REGIONAL DRAINAGE PLAN PHASE III
COMBINATION ALTERNATIVE SUPPLEMENT TO PHASE n PRELIMINARY ALTERNATIVE DESIGN REPORT PREPARED FOR: GALVESTON COUNTY, TEXAS AND THE TEXAS WATER DEVELOPMENT BOARD PREPARED BY: WALSH ENGINEERING, INC. In Association with: DODSON & ASSOCIATES, INC. VAZQUEZ ENVmONMENTAL SERVICES, INC. and VERNON G. HENRY & ASSOCIATES, INC.
PRELIMINARY DRAFT FOR REVIEW May 30,1994
The results from the HEC-l analysis using the rain gage data produced a peak flow rate of 38,000 cfs (at State Highway 146) as compared to a flow rate of 27,000 cfs predicted for a 24-hour, 100-year storm. This indicates that the overall rainfall totals for the Dickinson Bayou watershed were well above levels associated with a lOO-year frequency storm event. A study of the existing conditions in the watershed and in Dickinson Bayou and its tributaries was completed to update the lOO-year flood plain boundary and identify the current potential for flooding damage. The complete study is presented in two reports: «Dickinson Bayou Regional Drainage Plan: Hydraulic Baseline Report' (August 1992) and «Dickinson Bayou Regional Drainage Plan: Supplement to Phase I Hydraulic Baseline Report' (October 1993). A brief summary of the results of the study are presented here. A lOO-year storm, a rainfall event that has a 1% chance of occurring in any given year, would produce a total of approximately 13 inches of rain over a 24-hour period. If this storm occurred over the Dickinson Bayou watershed, the results as shown in Exhibit 5 are predicted to occur. Approximately 35,000 acres, or 55 % of the watershed area, would be in the flood plain. The depth of water would vary from inches at the fringes of the flood plain to almost 18 feet deep along Dickinson Bayou upstream of Cemetery Road. Most minor road crossings would be overtopped and major roadways such FM 517 at Dickinson Bayou and Gum Bayou, Cemetery Road at Ditch 90, State Highway 3 at Benson Bayou, FM 646 at Benson Bayou and Gum Bayou, and FM 1266 at West Gum Bayou would also be overtopped. The main bridges of Interstate Highway 45 and State Highway 6 would remain passable for all traffic from the area and also from Galveston Island if an evacuation was ordered. The cost of flood damages as a result of a 100-year storm occurring in 1993 is estimated to be $97,051,100. A breakdown of this estimated cost is presented in Table 8.
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Preliminary Combination AlfernaHve Number 3 The City of League City Master Drainage Plan included regional detention facilities in the Bensons Bayou and Gum Bayou watersheds_ In order to provide coordination with the League City plan, Combination Alternative Number 3 includes full detention for these two tributaries_ Other aspects of this alternative are identical to Combination Alternative Number 2. The HEC-l hydrologic analysis of this alternative indicates that, because of timing effects, regional detention in the Bensons Bayou watershed actually increases IOO-year peak flow rates in Dickinson Bayou. Therefore, regional detention is not recommended for this tributary. For Gum Bayou, the regional detention facility provides a decrease in IOO-year peak flow rates in Dickinson Bayou. However, these peak flow rates are already well below existing levels because of the presence of other regional detention basins throughout the Dickinson Bayou watershed. In addition, the reach of Dickinson Bayou below the Gum Bayou confluence is subject to inundation by the IOO-year storm surge from Galveston Bay. Therefore, the incremental cost of regional detention in the Gum Bayou watershed does not provide any significant incremental benefit in the form of flood plain reduction.
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CONCLUSION OF ANALYSIS
The following conclusions may be drawn from the results of the alternatives analysis. 1) The Channelization/Diversion Alternative has the lowest cost, but will involve the greatest environmental damage and thus the highest environmental mitigation cost.
2) The No-Action Alternative clearly involves the highest total cost and the greatest flooding potential of the five alternatives.
3) The Non-Structural, Detention, and Combination Alternatives are comparable in terms of cost, but the Non-Structural Alternative will create the least amount of environmental damage.
4) The Channelization/Diversion, Detention, and Combination Alternatives leave far smaller amounts of residual flood plain than the No-Action and Non-Structural Alternatives, thus providing the greatest potential for future development and economic growth.
5) The Non-Structural Alternative will result in major losses in taxable property by rendering the flood plain undevelopable and under public ownership. The amount of developable acreage left in the watershed under this alternative may not be adequate to support the cost of the plan.
6) The Combination Alternative will probably be the most effective in terms of meeting the goals of lowering the total cost, reducing the residual flood plain and potential flood damages, increasing the potential for economic development and the capacity to fund a regional drainage plan, and providing environmental safeguards.
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As expected, the No-Action, Non-Structural, and Detention Al- RECOMMENDATION ternatives have a very high cost per net acre when compared to the Channelization and Combination Alternatives. In addition, the implementation of these alternatives is unlikely due to unacceptable socioeconomic and environmental concerns. The Channelization/Diversion Alternative is approximately 25% cheaper than the Combination Plan. However, the Channelization/Diversion Alternative is not likely to be implemented, for the following reasons:
• Extremely wide right-of-way for channel expansion will be required;
• Residential property and business will have to be displaced to make room for channel improvements;
• A large initial cost is involved which is difficult to divided into phases;
• The environmental impact to sensitive areas may be significant enough to be unacceptable to regulatory entities;
• The plan may not have public support.
Therefore, the Combination Alternative is recommended as the preliminary design of the final drainage plan for the Dickinson Bayou watershed. The final plan will be developed in detail upon review and comment of this report by the Texas Water Development Board, Galveston County and all other entities participating in this study. The final plan is likely to be divided into a series of several short-range and long-term plans, based on location and timing of drainage facilities that are normally associated with development trends.
Dickinson Bayou is a 22.7-mile-long, slow-moving coastal stream that drains into Dickinson Bay, a subunit of the Galveston Bay system. Along most of its length the bayou is tidally influenced, while the uppermost reach, from its headwaters to 2.5 miles downstream of FM 517, is not. Dickinson Bayou has ten main tributaries: Oak Creek, Algoa Bayou, and Hickory Bayou in the portion above tidal influence and Gum Bayou, Bensons Bayou, Giesler Bayou, Bordens Gully, Cedar Creek, Hulen Park Bayou, and Arcadia Bayou in the tidal portion. Near its mouth Dickinson Bayou has a significant deep section, where the bottom of the channel dips below the level of the channel at the outlet to Dickinson Bay. This deep section affects the mixing of salt and fresh water in the bayou and the water’s flow to the bay.
This deep section affects the mixing of salt and fresh water in the bayou *and the water’s flow to the bay.
*and the water’s flow to the bay.
Stream segment 1104 is Dickinson Bayou above tidal reach which flows 7.3 miles from FM 528 to 1.2 miles downstream of FM 517. Segment 1103 is the Dickinson Bayou tidal reach which starts 1.2 miles downstream of FM 517 and flows 16.4 miles to the Dickinson Bayou confluence with Dickinson Bay. Flow regimes in the two reaches are markedly different. The above tidal reach is a relatively narrow, shallow stream (1 to 3 ft deep) with moderate to slow moving water, whereas the tidal reach is a wider, predominantly deep channel (5 to 20 ft deep) with very sluggish flow.
Streamside vegetation is characteristic of the two stream segments flow regimes. The above tidal reach is characterized by dense riparian vegetation that limits sunlight exposure whereas vegetation in the tidal reach is less dense and allows more exposure to sunlight. The topography of the watershed slopes gently towards the bayou. Landsurface altitude varies from about 50 feet above mean sea level in the western edge to sea level at the eastern mouth of the Bayou. Soils are clays or loams with low permeability. The narrow, shallow channels of the headwaters to Dickinson Bayou are often blocked by fallen trees and scrub-shrub debris. These natural “snags” from trees and debris slow down the flow of flood waters and have caused over-bank flooding into riparian and coastal flatwood forests along the bayou as well as urban development projects.
Spillway inlet outlet canal Permit 5972 Hwy 146 Bacliff Texas pdf file
The HL&P canal was initially dredged in 1972. According to specifications contained in the permit, it was to be 18 feet deep all the way from Galveston Bay to Dickinson Bayou. The same permit contained provisions that Dickinson Bayou was to be dredged out all the way out to the Houston Ship Channel. This was never done, not even one time.
This is the specific wording used by the US Army Corps of Engineers in writing to HL&P, before they issued the initial permit which created the canal:
"The decision as to where a permit will be issued will be based on an evaluation of the impact of the proposed work on the public interest. Factors affecting the public interest include, but are not limited to, navigation, fish and wildlife, water quality, economics, conservation aesthetics, recreation, water supply, flood damage prevention, ecosystems, and in general the needs and welfare of the people."
The above was written by the district engineer of the Galveston District, Corp of Engineers. On May 10, 1972, Mr. D. E. Simmons, Vice President of Environmental and Inter-Utility Affairs for Houston Lighting and Power stated in writing to the Corp of Engineers that "continued maintenance is planned." In response, the Corp of Engineers issued a Public Notice on November 9, 1972 announcing plans for the HL&P proposals which included the obligation for the utility company to perform continued maintenance dredging. It was understood and agreed upon that the utility would maintain the canal by periodically dredging it and the adjoining bayou, in order to prevent what has now happened. As stated earlier, no such dredging has ever been performed since that 1972 statement. Due to the fact that the dredging maintenance was never performed, the HL&P canal and Dickinson Bayou have both filled in on the ends. This has caused what is called a ''Hydraulic Effect". Hydraulic Effect on Dickinson Bayou means the bayou is twenty-five to thirty feet deep until it gets close to the bay where it shoals to just six or eight feet. That that the bayou cannot ever flow correctly and get properly flushed out. All of the sediment from runoff collects into the mud of the bayou (ie: fertilizer, pesticides, and the waste from the sewer plants.) If the mouth of this bayou and both sides of the HL&P canal were continually dredged as stipulated in the original permit, this hydraulic effect would not be in play. If the bayou was dredged as stipulated in the permit, the lab analyst said that Dickinson Bayou would healing itself immediately. He said, "Mother Nature will eat up all the black muck with natural bacteria once there is a normal oxygen level and good tidal flow. This applies to the canal as well.
Dickinson Bayou and the shoreline can be fixed. It can be a vibrant, aquatic productive estuary once again. Dolphins, alligators, and all manner of wildlife once lived there. The reason our bayou has died is because someone didn't do what they said they were going to do, what they were in fact obligated to do legally.
Who is responsible for this major screw-up? I believe it is a combination of HL&P not doing the dredging they agreed to do, and the Army Corps of Engineers not verifying that work was performed. It all has to do with money. We have put all of the documentation on our web site. To see the flounder kill video and copies of the permits and the drawings of the proposed dredging that was never done please visit
You do not need to be a subscriber to see this information.
A special thanks to Terry Singeltary of Bacliff for all of his help and support. Also, thanks to Texas A&M Galveston Marine Biology Department for their input. We are not finished with our investigation. Look for continued coverage in the next issue of the Seabreeze News. We will be in contact with the Galveston Bay Foundation and their attorney, seeking their knowledge and expertise.
We hope to find some way to open up Dickinson Bayou and both sides of the HL&P canal in order to facilitate the healing and restoration of our bayou and shorelines, as was expressly promised in the contract.
I have never been a ''tree hugger", but we cannot stand by and allow our coastal waters to be destroyed in the name of the almighty dollar, especially when the solution to the main problem is so simple. If you have any information to share or "comments please write us at the Seabreeze News or send an email to:steve@Seabreezenews.com. Steve Hoyland Sr. www.SeabreezeNews.com
Spillway inlet outlet canal Permit 5972 Hwy 146 Bacliff Texas pdf file
kind regards, terry
Terry S. Singeltary Sr., Bacliff, Texas USA 77518
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