Champions Stormwater Detention Basin K500-24-00

Long-term, the Flood Control District plans to build a stormwater detention basin on this property, depending on continued negotiations with the CFPUD. No decisions have been made at this time.

The Flood Control District will be responsible for appropriate security, maintenance and upkeep of this property.

The Cypress Forest Public Utility District will have access to their water plant.

Negotiations with the CFPUD are ongoing and no final determinations have been made to date. Ultimately, Flood Control District options include:

• Continuing negotiations and reaching agreement with the CFPUD on a deal that involves the clubhouse property and other property suitable for a flood risk reduction project.
• Cancelling the flood risk reduction project and selling the Raveneaux property to recover acquisition costs.
• Using the eminent domain (condemnation) process to acquire additional property needed for flood risk reduction at fair market value.

The property is being acquired for a regional stormwater detention basin that will reduce flooding risks along Cypress Creek. At this time, there are no specific plans for the size, design, or other features of that basin. A detailed plan will be developed in the future during the preliminary engineering process, which will include community engagement.

Stormwater detention basins reduce flooding risks by taking in and holding stormwater during heavy rain events and slowly releasing it back to the creek or channel after the threat of flooding has passed.

The Flood Control District is working on a preliminary estimate of how many homes in the Cypress Creek watershed would have a lower risk of flooding if a large stormwater detention basin were excavated on this property. This estimate would be based on an assumed basin size; no decision has been made about the footprint or other specific features of the proposed basin.

Specific details about this project have not been decided or designed, and will not be decided or designed without public engagement.

The Flood Control District does not build, operate or maintain facilities such as trails, sports fields or playgrounds. However, the Flood Control District does support multiple uses of its property for other compatible recreational uses that do not interfere with a project’s flood risk reduction function.

We work with many partners around Harris County that design, build, and maintain compatible recreational amenities on flood control land.

In general, the Flood Control District supports establishing/maintaining a wooded riparian corridor along Cypress Creek to help prevent future bank erosion. The Flood Control District is also interested in planting a large number of trees in key locations for environmental benefits, and to reduce required maintenance. Such plantings would have the added benefit of being aesthetically pleasing.

The Flood Control District makes no promises to anyone as to the future details of the property. However, the Flood Control District is committed to seeking public engagement and input, even if we cannot ultimately provide all that the community might request.

The Flood Control District cannot predict how property values will change as a result of this proposed project. However, the Flood Control District knows that properties with a lower risk of flooding have a higher value than properties with a high risk of flooding.

The 2018 HCFCD Bond Program requires community engagement during the preliminary engineering phase of the HCFCD project lifecycle.

A detailed plan for additional community engagement in connection with the Raveneaux sale and flood risk reduction project has not been developed, but it is the Flood Control District’s intent to be transparent about our future plans for the property. Please watch this webpage for updates.

Upcoming Community Engagement Meetings are listed here:
https://www.hcfcd.org/Resilience/2018-Bond-Program/Community-Engagement-Meetings

More information about the typical project lifecycle is here:
https://www.hcfcd.org/Resilience/2018-Bond-Program/Project-Lifecycle

Flood Control District property acquisitions are handled by the Harris County Real Property Division with direct involvement of Flood Control management.

Arthur Storey Park

The Hill at Sims Greenway

Willow Waterhole Greenspace

Brays Bayou Park

Harris County Deputy Darren Goforth Park on Horsepen Creek

Keith-Wiess Park

As with other natural channels in Harris County – such as Buffalo Bayou, Spring Creek, Luce Bayou, Jackson Bayou, Armand Bayou, Cedar Creek and Little Cypress Creek – the Flood Control District has no plans to concrete-line or rectify (straighten and remove meanders from) Cypress Creek. It is not a simple process to rectify, concrete-line, or widen/deepen a natural channel. Any of these would be extremely costly, i.e. more than the 2018 Bond Program could fund. This is because of the combination of property acquisition, flood mitigation, environmental permitting and environmental compensatory mitigation that would be required.

Cypress Creek and other channels in their current naturalized state are considered by our federal government to have significant environmental value. They are part of the “waters of the United States” protected by the federal Clean Water Act. Reducing that environmental value by dredging, widening, deepening, straightening, concrete-lining etc. would require an environmental permit from the U.S. Army Corps of Engineers. That process alone is lengthy and expensive. IF granted at all, the permit would require replacing the lost environmental functions and values of the impacted streams and wetlands with similar or better functions and values within the same watershed, through a process known as compensatory mitigation. 

Compensatory mitigation can be quite expensive, in the millions of dollars per mile of impacted channel, whichever method of mitigation is chosen. For example, compensatory mitigation could involve purchasing credits in an environmental mitigation bank, if one is available. Or, it might involve a special type of channel design that would require a wider waterway corridor, meaning homes and businesses along Cypress Creek would need to be acquired and demolished to make room. In order to provide a 100-year level of service, the Flood Control District estimates the environmental mitigation costs alone to be greater than $262 million. 

Any project that would provide faster stormwater conveyance – especially rectifying or straightening –also would require additional, expensive property acquisition for stormwater detention to mitigate for the increased flow, to ensure that it does not flood people downstream. People who live or own businesses along Cypress Creek may not be willing to sell their properties for this purpose. The Flood Control District estimates the property acquisition costs to be greater than $600 million. The Flood Control District estimates the costs for 30 bridge replacements and 75 pipeline adjustments to be greater than $177 million. 

In total, to channelize Cypress Creek to provide a 100-year level of service would cost more than $3 billion. This total amount includes: wetlands mitigation, streambank mitigation, right-of-way acquisition, building acquisition, demolition, channel excavation, turf establishment, bridge demolition and reconstruction, pipeline adjustments and relocations, engineering costs, and a construction contingency. A project of this magnitude could take decades to complete. 

This type of project would require the removal of all or most of the riparian forest that now lines much of Cypress Creek. While some residents may be in favor of rectifying/deepening/widening, there is also strong community support for protecting Cypress Creek and allowing it to remain in a naturalized state. 

The Flood Control District may remove accumulated sediment and debris from a natural channel as part of a maintenance project, but not in a way that deepens or widens the creek. Maintenance projects that restore channel conditions of historically rectified channels to pre-storm dimensions (width, depth and bank slope) can typically be authorized under the Clean Water Act by a general permit, also known as a Nationwide Permit. Nationwide Permits are intended for activities that exhibit minimal adverse environmental effects, such as restoring a historically rectified channel to its pre-storm condition. Projects or activities that improve the condition of both historic and natural channels with respect to capacity (width and depth), lining, and location require an Individual Permit and compensatory mitigation for any lost aquatic resource functions. The process to assess and document existing aquatic resource values and develop a mitigation plan to compensate for temporary and permanent impacts is time-consuming and costly due to the coordination with regulatory agencies and other stakeholders.

Flood Control District officials have met on several occasions with various groups who want to redesign the Raveneaux property in various ways. We are listening and considering these plans for their viability and compatibility with much needed flood risk reduction.

Please continue to visit our webpage for this project to get updates as the situation develops.

These are the facts:

• The Flood Control District has not reached a decision on basin design, so it is too early to say how many trees might be removed in connection with this project. Decisions on basin design, which will be made after community engagement, will have a significant impact on where trees will need to be removed, where existing trees can be relocated, and where they can be preserved.
• We have received numerous comments regarding what the view would look like along Cypresswood Drive. The Flood Control District is open to the idea of maintaining a 300-foot-wide buffer along Cypresswood Drive, which would mean that no trees would be removed in that area. The District and other agencies may want to plant additional trees in this 300-foot-wide buffer area. But as with all aspects of design, no final decisions have been made.
• There are already open areas on the golf course property – areas where trees were removed during creation of the golf course.
• The Flood Control District is committed to reforesting areas that were cleared along the banks of Cypress Creek when the golf course was built. This step will prevent erosion, reduce maintenance costs, and add to the environmental diversity of this important riparian corridor.
• As part of the engineering process for a future stormwater detention basin, the Flood Control District will perform a tree survey and inventory – conducted by licensed arborists -- that will count and categorize all trees of a certain size. This will provide the public with a better understanding of the environmental value of the trees on the site, and also provide some guidance for future basin design. This survey may be part of the design process, or it may be done earlier, during preliminary engineering. When this tree survey takes place, residents may notice tags on trees. These tags indicate that the tree has been inventoried for planning purposes; it does not necessarily mean that the tree is tagged for removal.
• Reforestation (new tree plantings) will be included in any basin design project.
• The Flood Control District has a Tree Planting Program that plants an average of 12,000 native trees each year at basins and along bayous.
• If and when a sponsor steps forward to construct and maintain recreational amenities, that sponsor might also plant trees.

The Flood Control District plan is to construct a stormwater detention basin to reduce flooding risks. Based on knowledge of the Cypress Creek floodplain, hydrology and hydraulic principles, and decades of professional drainage engineering experience in the watershed, the Flood Control District has conclusively determined that the Raveneaux property is an excellent candidate for a stormwater detention basin to reduce flooding risks in the area.

However, a final decision has not been made on the specific design of this basin, and no final decision will be made without public input. The final design determines which areas will be cleared, which areas will covered by water, and which areas may contain future recreational amenities.

Any drawings or other depictions of the property at this point are only possible options, out of many options ranging from the maximum stormwater detention possible, to layouts that feature any combination of potential community amenities. They do not reflect a decision or a preference by the Flood Control District.

Public input will help the Flood Control District balance potentially competing community interests for maximum flood risk reduction vs a desire for greenspace, tree buffers and other elements that can impact the potential capacity of the project, as well as its cost. Many Flood Control District detention projects are a product of a similar balance between maximum capacity and other basin design elements.

Most details of “how the basin will look” are to be developed during the design phase and following community engagement. However, at this very early stage, some aspects are likely:

The basin will be excavated down into the ground, past the natural water table in one or more areas, and so the basin would include one or more permanent pools. These would look like individual lakes or ponds within the overall basin banks. The vertical space above the natural water level to the top of basin banks at ground level is what provides the stormwater storage.

Multiple pools, rather than just one large pool, are common in some, but not all, Flood Control District regional stormwater detention basins. Multiple compartments allow for stormwater quality improvement features, tree preservation and community amenities (when a willing partner steps forward), and add to the basin’s overall aesthetic appeal.

Some existing trees would remain between and around the compartments that are excavated.

This is a common question! It is the vertical area above the natural water level -- up to the top of the basin’s banks -- that provides the extra storage for potentially millions of gallons of stormwater.

Unlike some parts of the country with natural hills and valleys that can be dammed up to hold water, Harris County is flat. Stormwater detention basins in Harris County are excavated down into the surrounding ground to provide a holding area.

Some of these basins are designed to be dry except during a rain event. They are typically connected to a bayou by way of a “weir” – like a large notch in the bayou bank. They fill with stormwater only when stormwater rises to the level of the weir and spills over into the adjacent excavated basin.

Other basins are excavated down past the natural water table, and so the compartments would have one or more permanent pools at the natural water level. These pools provide environmental benefits such as habitat for native plants and animals, and improved water quality. They would look like lakes or ponds, rather than dry grassy depressions in the ground.

A stormwater detention basin does not suddenly overflow in all directions like a bathtub, or open by means of a gate etc. It has no gates or mechanical devices. The top of the basin is at ground level, not behind an embankment or levee that could fail. The Flood Control District does not build levees for just that reason: The danger of a sudden breach.

Instead, our stormwater detention basins are connected to the creek by means of a weir – like a notch in the side of the creek bank. A stormwater detention basin is an extension of the natural floodplain that is excavated down into the ground and fills as the water rises in the connected creek, and then typically drains by gravity more slowly back into the creek via an outfall pipe as stormwater in the channel decreases.

It might be helpful to imagine if the basin was not there. Currently, if the creek rises up and out of its banks, the stormwater overflows across the (unexcavated) land and – depending on rainfall – possibly into people’s homes. However, with a new storage area, that same stormwater has a safe place to go, so that it does not impact structures. This reduces flooding risks.

If the rainfall is so heavy and continuous that stormwater completely fills the basin, level with the surrounding ground, the stormwater already in the basin would remain there, the basin just wouldn’t take in any more. However, the basin would continue to hold its capacity of stormwater that otherwise could have resulted in worse flooding, sooner.

This is a common misconception. Flood Control District engineers design our stormwater detention basins – whether wet-bottom or dry-bottom – to naturally discourage mosquito breeding. Proper basin design and maintenance limits mosquito breeding without the need for insecticide or compromised water quality.

The facts are that mosquito larvae prefer to breed in stagnant water less than three feet in depth. A typical Flood Control District wet-bottom basin will be roughly 3 to 8 feet deep. Water within the basins flows rapidly during rain events, but also flows slowly during the intervals between storms, so it is never stagnant.

Natural habitats improve stormwater quality and aesthetics and provide ecosystem diversity that has been shown to prevent mosquito outbreaks by providing habitat for mosquito predators (birds, bats, fish, dragonflies, spiders, and a wide variety of aquatic insects).

The Flood Control District has also recently implemented the design of a “dragonfly pond”, which optimizes habitat opportunities for these mosquito predators. The conceptual design in the flyover video shows that this idea can also be implemented at the top of the basin banks, so that stormwater already flowing from neighboring streets can flow through the pond and be filtered, before being discharged into the main water body of the basin.

No single project can provide all the stormwater detention capacity that the Cypress Creek watershed needs. Much of the area was developed before the 1980s, when stormwater detention requirements went into effect. In fact, the neighborhoods surrounding the Raveneaux Country Club were constructed without stormwater detention basins.

A Flood Control District study completed in 2019 recommended more than 25,000 acre-feet of new stormwater detention to reduce flooding risks in the Cypress Creek watershed. (This is in addition to the roughly 17,000 acre-feet proposed for Little Cypress Creek, which is actually a tributary of Cypress Creek.)

While more detailed preliminary engineering has not been conducted on the Raveneaux site, it is estimated that this site alone could provide around 3,000 acre-feet of detention, depending on design and additional factors yet to be determined.

Suitable locations for regional detention – such as the Raveneaux property -- are limited in a heavily developed watershed such as Cypress Creek. The Flood Control District is also pursuing multiple other stormwater detention basin projects in the Cypress Creek watershed on land it already owns, and is looking at all property available through willing sellers for additional acquisition. All of these projects are necessary to provide needed stormwater detention for the Cypress Creek watershed.

We urge every resident to expand their idea of the neighborhood to be as large as their watershed. Our waterways are interconnected across Harris County. Anything that happens in your watershed can benefit your friends and neighbors.

It will take support throughout the Cypress Creek watershed to build the stormwater detention that the watershed needs to help all areas of the watershed.

The Flood Control District is actively considering all available properties throughout the watershed to provide the 25,000 acre-feet of stormwater detention recommended for the Cypress Creek watershed.

You are correct that recreational amenities depend upon a third-party sponsor stepping forward to build and maintain trails etc. on Flood Control District property. This is true at all Flood Control District facilities, county-wide.

However, many Flood Control District stormwater detention basins and bayous around the county have been equipped in recent years with trails and recreational amenities via sponsors. Harris County Commissioners, the City of Houston, various Municipal Utility Districts, etc. have also constructed parks, trails and even sports fields on land designed and used for flood damage reduction purposes in major storm events. The Houston Parks Board is investing more than $200 million with the Bayou Greenways project. All these groups would be proud to provide information about the work they have been able to do, using publicly owned land shared by the Flood Control District. This partnership work has won awards for Harris County, as well as attention from the national news media.

Generally, the Flood Control District is responsible for maintenance such as mowing, debris removal, and vegetation management of its properties. However, if and when a sponsor takes over responsibility for building and maintaining a recreational amenity on our property, that sponsor would be the one to mow and maintain.

We also recommend visiting multi-use sites in person to get an idea of how flood damage reduction projects can co-exist with usable open space.

The final elevation difference is ultimately governed by several factors: the existing natural topography of the site and its surroundings, the existing normal surface water level of the bayou, and the amount of site design and engineering and earthwork re-shaping desired for the project.

The Flood Control District typically uses a 4:1 slope when designing basins. If a 4:1 slope is used, and the elevation difference from the normal water level of the basin to the top of bank is 25 feet, then the water will be 100 feet horizontally from the top of bank. If gentler slopes are used (to create variable side slopes as a feature of Flood Control District wet-bottom detention basins), then the water will be farther away, possibly up to 300 feet or more in a few locations around the basin.

For Flood Control District wet-bottom detention basins, the design standard is to have a maximum six to eight feet of water depth under normal, sunny day conditions. Wetland edges around the perimeter of a basin vary in depth from six inches to three feet before transitioning into open water; this range of depths support a variety of wetland species that contribute to water quality enhancements.

Water appears blue only when it is very deep (because of the way water absorbs light), so if the maximum depth of a Flood Control District basin is eight feet, then it is not physically possible for the basin water to appear blue unless it is reflecting the sky on a clear day.

However, the water in bayous and basins can appear clearer or murkier. The water in Houston’s bayous is generally brown (i.e. muddy) because of suspended sediment due to the increased amount of stormwater that flows into them as a result of the amount of development and impervious cover (rooftops and paving) in the region. Before Houston was developed, the bayous were much clearer.

Today, bayou waters can become clearer as sediment drops out of them, but if a storm event occurs, they can become browner and muddy again with the new influx of sediment. Given that Cypress Creek is typical of this type of developed watershed, the basin will likely reflect the condition of the bayou the more frequently it fills with stormwater from the bayou, and then the sediment can settle out the longer it goes without being filled with water from the bayou.

In terms of vegetation appearance, stormwater quality wetlands that line the edges of the basin also help to filter the water and create visual appeal, and low islands that do not significantly impact detention volume can support lowland vegetation and trees and create beneficial habitat. Because of the size of the basin and the fact that water will always be moving very slowly through it under normal conditions, algae growth should not be a factor.

The Flood Control District preliminarily names basins by the nearest roadway, which in this case is Champions Drive. The final name of the basin will be determined through further input.