Cypress Creek FAQs

Cypress Creek FAQs

Last Modified: 12/27/2019 04:18 PM

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Cypress Creek FAQs

What is a maintenance project versus a capital project?

A maintenance project repairs or maintains what already exists.

A capital project expands or improves the current drainage system.

What is a bond project versus a capital project?

They can be the same.

“Bond” refers to the method of financing – the voter-approved, $2.5 billion 2018 HCFCD Bond Program. Before there was a Bond Program, the Flood Control District had a dedicated Capital Improvement Program (CIP) of about $60 million per year to design and build countywide flood risk reduction projects, including the studies that led to those projects. A “capital project,” is a project that provides new or higher-capacity flood risk reduction infrastructure, rather than a project to repair or maintain what already exists. 

A “bond project” is any project financed by the 2018 HCFCD Bond Program. Bond projects may include: 

• Flood risk reduction projects, also sometimes referred to as “capital projects” 

• Major or large-scale maintenance projects 

• Land acquisition 

• Regional drainage studies 

So a bond project is often a capital project. A capital project can be a bond project or financed in some other way. 

Now that bond funds are available, the $60 million per year previously earmarked for the CIP will go toward the increased cost of operating and maintaining an expanded drainage system.

What is the intent of maintenance projects such as Bond Project CI-012?

Engineered, man-made channels are typically built with an established/documented depth and width. Let’s call that Original Configuration A. Over time, a portion of that depth and width may be partially impacted with layers of sediment and other material that ends up in drainage channels, such as vegetative debris and trash. Channels can also erode over time. This erosion could be a source of material in a channel. Let’s call that Eroded Configuration B.

While sediment generally tends to shift each time there is a major rain event, causing little impact on flood risk, in extreme cases this accumulated material potentially could reduce “channel conveyance,” which is the channel’s ability to move stormwater. Erosion of the channel side slopes could also potentially impact channel conveyance.

A maintenance project removes the sediment and repairs erosion, restoring channel conveyance and returning the channel to its Original Configuration A. This is potentially better for stormwater conveyance than Eroded Configuration B, but it does not widen or deepen BEYOND the Original (engineered) Configuration A.

In other words: Let’s say a channel is originally designed and built with a 1 percent (100-year) level of service. Accumulated sediment or erosion reduces that level of service to something less than the 1 percent (100-year) level of service. Removing the sediment and repairing the erosion allows the channel to carry more stormwater than it did WITH the sediment or erosion, but it is still no more than the original 1 percent (100-year) level of service.

Maintenance is positive, but it has limits.

Maintenance projects, in general, do not require the same degree of environmental permitting and mitigation as channel widening/deepening/straightening/concrete-lining, because maintenance projects do not alter the channel’s original configuration.

Maintenance can also take place on a non-engineered, natural channel, but that is a much more rigorous, time-consuming process, because of environmental permitting and compensatory mitigation requirements.

Why can’t capital projects and maintenance projects be conducted at the same time on the same channel?

As discussed above, the different requirements for environmental due diligence between a capital project (to reduce flooding risks) and maintenance project (to restore a channel to its original configuration) place them on very different timelines – sometimes years apart. 

Funding levels before the 2018 Bond Program resulted in deferred maintenance on many channels in Harris County. In some cases, now that bond funding is available, the Flood Control District has chosen to move ahead with projects that can be done now, such as Major Maintenance. Meanwhile, more extensive pre-project work on capital projects that will increase the level of service and reduce flooding risks (which could take years) continues on a separate but coordinated track.

Will the 2018 Bond Program prevent all flooding in the Cypress Creek watershed?

No. All watersheds in Harris County – including Cypress Creek watershed – are at risk of flooding. That is because Harris County is flat, has impermeable clay soils, and is prone to severe rainfall, including tropical storms and hurricanes. While the $2.5 billion 2018 Bond Program will reduce flooding risks across the county – including in Cypress Creek watershed – it will not eliminate those risks entirely. It has been estimated that it would take approximately $4.5 billion in Cypress Creek watershed ALONE to give it 1 percent annual chance (100-year) protection. Even with that expenditure, there would still be flooding risks. Any watershed in Harris County can flood, given enough rain over that watershed. Many projects from the Bond Program are already underway, and will be completed as soon as possible in the next months and years. It will take approximately 5-10 years to complete the entire program.

Why are Stormwater Detention Basins an important part of the Flood Control District’s strategy in the Cypress Creek watershed?

Stormwater detention basins are large excavated areas engineered to take in and temporarily hold excess stormwater during heavy rain events. They can prevent or reduce the amount of stormwater that overflows the bayou or creek banks. The water drains from the basin back into the bayou or creek slowly, by gravity, as water levels recede. 

A regional drainage study for the Cypress Creek watershed found that flooding along tributaries of Cypress Creek is predominately caused by water from a rising Cypress Creek backing up into tributaries, rather than a lack of sufficient stormwater conveyance/drainage capacity on the tributaries themselves. Therefore, stormwater detention basins could be a beneficial project to reduce that backwater issue. 

The regional drainage study described here recommends nearly 25,000 acre-feet of additional stormwater detention in the watershed.

Why is property acquisition a large part of the Flood Control District’s strategy in the Cypress Creek watershed?

Much of the Cypress Creek watershed was developed before our current scientific understanding of flood risks in Harris County, and before current stormwater mitigation requirements. Simply put: Homes and businesses were built in the wrong places. Some flood-prone areas cannot be helped by a flood risk reduction project. In some cases, buying floodplain properties to prevent development, or buying out an already-developed flood-prone property and moving the resident to a safer area, is the best or the only option. 

Many flood risk reduction projects – such as stormwater detention basins – require the purchase of additional property. Property acquisition is sometimes the most time-consuming and expensive part of any project. During a period of limited funding, the Flood Control District focused on floodplain preservation and buyouts. Now that additional funding is available, we are working on more projects and acquiring more project-specific properties. 

Bond Project F-20 includes $100 million for Cypress Creek Right-of-Way Acquisition and Floodplain Preservation. Between August 2018 and late 2019, the Flood Control District has purchased three tracts totaling 78 acres at a cost of roughly $1.5 million. Four additional tracts were in the process of acquisition in late 2019. 

Other Recent statistics: 

As of late 2019, since Harvey and the Bond Program, the Flood Control District has acquired 

• 80 voluntary home buyouts 

• 3 floodplain preservation tracts, at a cost of approximately $1.5 million (with an additional 52 tracts in process) 

• 10 tracts for Stormwater Detention Basin projects 

Since the Voluntary Home Buyout Program began in the 1980s, in Cypress Creek watershed, the Flood Control District has acquired: 

• Nearly 400 homes, 

• 130 of which were in the last 10 years 

• In 15 areas of interest in Cypress Creek watershed, 

• Mostly downstream from the confluence with Little Cypress Creek

What is meant by “Level of Service (LOS)” and what is the Cypress Creek watershed LOS?

For the Flood Control District, Level of Service refers to the level of storm event that can be carried within the banks of a particular drainage channel, before it overflows and begins to affect nearby structures. One channel might be able to handle a larger 1 percent (100-year) storm within its banks, while another can only handle a smaller 10 percent (10-year storm) without overflowing. 

There is no single Level of Service for Cypress Creek watershed. The LOS for each channel in a watershed is potentially different. Natural channels were generally created by nature, and can change or be modified over time. Engineered drainage channels in Harris County were built at various times and by various entities over time. LOS is not the same across the county, within a watershed, or even along the entire length of the same channel. 

In late 2019, the Flood Control District initiated a project to determine the LOS of all channels in our Harris County drainage network. Initial results are expected in 2020, including for the Cypress Creek watershed. 

Additionally, the Flood Control District and FEMA are re-mapping all of the floodplains in Harris County. The Cypress Creek watershed is currently being modeled and preliminary results could be available as early as April 2020 for Cypress Creek. 

http://www.hcfcd.org/Resilience/Countywide-or-Multi-Watershed/Z-03-Level-of-Service-Analysis 

http://www.maapnext.org

Can Cypress Creek be dredged, deepened/widened, straightened, and/or concrete-lined to improve the Level of Service?

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.

Will stormwater detention basins be “multi-use” for recreation in a way that is an asset to the community?

The Flood Control District’s stated mission is to “provide flood damage reduction projects that work, with appropriate regard for community and natural values.” The Flood Control District supports the multi-use of its facilities for recreation and open space, as long as there is a funding partner to build and maintain those amenities, and those activities do not interfere with the property’s primary flood risk reduction purpose. 

The Flood Control District’s Policy, Criteria, and Procedure Manual states “HCFCD recognizes the opportunities presented by HCFCD facilities to enhance both community and natural values. Consequently, HCFCD supports and encourages such multi-use functions as trails, green space, parks, greenway or corridors, stormwater quality facilities, practice fields, and other recreational and natural features provided they are compatible with the primary function of the HCFCD facility. (See related Policy XIII, Natural Environments and Habitats.)” 

It is not part of the Flood Control District mission or enabling legislation to fund recreational amenities. We partner with agencies all over the county who want to fund and maintain trails, ball fields etc. along our bayous or at stormwater detention basin sites. This is a significant benefit to those agencies, because they do not have to spend their money to acquire new park and open space land. 

Partner agencies who seek to build/maintain recreational amenities on our flood control property sign a written agreement acknowledging the property’s primary flood control purpose. Meanwhile, the Flood Control District strives to make their job easier by close coordination during the engineering design and construction phases of our projects. 

Sometimes, during the project design stage, it is determined that an available site is too small, and the need for flood risk reduction is too great, to allow some of the land to be used for parking lots, ball fields, etc. This is a case-by-case determination. 

For those reasons, we can’t make a blanket statement that ALL facilities will have recreational amenities. However, we do support the multi-use of our property, and are willing to work with appropriate sponsors to achieve that goal. 

The Flood Control District also has a robust Tree Planting Program, and plants native wildflowers on flood control property. We do this because it provides maintenance benefits, and we conduct the plantings in a way that does not interfere with the property’s primary flood risk reduction purpose. Site beautification is an added benefit, but it is not the primary goal.

What can the Flood Control District do – what is its role – in addressing the Interstate Highway 45 bridge obstruction?

We have shared residents’ concerns with the Texas Department of Transportation, and that agency is looking into those concerns. 

In late 2019, the Flood Control District also asked our consultant, Michael Baker, who was hired to update a regional drainage plan for the watershed (Bond Project CI-035), to analyze additional potential stormwater conveyance improvements, including modifications to the Kuykendahl Road and IH-45 bridges over Cypress Creek. While the IH-45 bridge belongs to TxDOT, analysis by the Flood Control District to quantify the flood risk reduction benefits of modifying the bridge could facilitate a future partnership project. 

Michael Baker will look at various bridge modifications that could improve stormwater conveyance, and the Flood Control District will continue to coordinate with TxDOT.

Is upstream development causing the Cypress Creek watershed to flood?

All new development within Harris County must comply with strict requirements for detention. Development criteria have been in place for the last 30 years, and it is always required for any development in the county. These development criteria require that all new development mitigate for flooding/drainage impacts that may be caused as a result of the development.

Additionally, the Flood Control District has spent the past 10 years studying detention rates and release rate criteria with the Little Cypress Creek Frontier Program to ensure that new development will not impact downstream flooding. For more information about the frontier program, see

https://www.hcfcd.org/Find-Your-Watershed/Little-Cypress-Creek/F-26-Little-Cypress-Creek-Frontier-Program

Can the Flood Control District stop new development?

No. Development regulations are enacted by the governing jurisdiction for each area. That is the underlying municipality, such as the City of Houston, or Harris County government for unincorporated Harris County. The Flood Control District is not the floodplain administrator, nor do we have development codes. The Flood Control District is an agency of engineers and support staff that builds flood risk reduction projects and maintains this infrastructure.

It is the floodplain administrator that decides on land use and flood mitigation requirements, such as stormwater detention etc. Of course, the Flood Control District has expertise to offer in these areas, but the ultimate permitting decision is made by the permitting authority of the underlying municipality/county, as governed by elected council members, commissioners etc.

The Flood Control District does provide technical reviews for all development projects that outfall into or otherwise impact its drainage infrastructure, but this review does not involve deciding how land may be used, enacting development requirements, or permitting new development. This review makes sure the permitted development is to our minimum standards, and that there is no impact upstream or downstream in stormwater levels because of the new development that touches our infrastructure.

Each new development (of greater than one acre) must perform a drainage study, signed and sealed by the development’s design engineer, who is ultimately responsible for the accuracy of all calculations and the determination of no adverse impact.

If a development follows the requirements in place at the time that the project is permitted, the Flood Control District cannot “stop the development.”

One qualification: The Flood Control District has a floodplain preservation program that seeks to purchase and remove floodplain land from possible future development, or to purchase and clear the land if necessary and cost-beneficial. A determination of need and necessity by its governing body is required before the Flood Control District can use the “eminent domain” legal process to force a property owner to sell.

When developers build new home sites several feet higher than the original ground level, does this create more flooding downstream?

Developers are required to follow rules put in place to ensure that new development will not increase the risk of flooding for anyone else. In the case of a residential development involving the importing of fill dirt, some requirements are that:

• The volume of fill to be placed in a mapped floodplain is required to be offset by an equal amount of new storage. That is, a development that brings 1,000 cubic feet of fill into the mapped floodplain must build a detention pond to hold at least a 1,000 cubic feet of water to replace the lost floodplain volume.

• If a development has the potential to change the way water flows down a channel/bayou, they must do an analysis to demonstrate that the change would not increase the flood risk for anyone else.

Texas Water Code Section 11.086 also requires that the development ensure that it does not adversely affect the natural flow of surface waters around or through the development, so that neighboring properties are not affected.

Would lowering the level of Lake Houston before a storm provide flood risk reduction benefits for Cypress Creek?

No. This has been the subject of a preliminary engineering study and the benefits of lowering the level of Lake Houston before a storm were only for people living right around Lake Houston. There was no benefit on Cypress Creek, as Lake Houston has no effect on Cypress Creek water levels.

Would excavating the West Fork of the San Jacinto – after the confluence with Spring Creek and before Lake Houston – have an impact on Cypress Creek flooding?

No. The benefits would not extend to Cypress Creek. Dredging or excavating the West Fork of the San Jacinto River has no effect on Cypress Creek water levels.

Will current and proposed future projects for Cypress Creek be reviewed in terms of the most recent 2018 LiDAR (light detection and ranging) data?

Yes, this is already underway as part of the Harris County floodplain mapping effort known as MAAPnext.
Please visit www.maapnext.org.

Is tunneling a good option to prevent flooding by moving water underground to the Houston Ship Channel during major storms?

The Harris County Flood Control District is studying the feasibility of using large diameter tunnels for stormwater conveyance. So far, studies have not looked at specific tunnel alignments/locations. Please read the latest about tunneling here:
https://www.hcfcd.org/Resilience/Countywide-or-Multi-Watershed/Z-08-PRELIMINARY-ENGINEERING-STUDY-FOR-LARGE-DIAMETER-TUNNELS-FOR-STORMWATER-CONVEYANCE

What is the Cypress Creek Overflow?

The Cypress Creek Overflow is a natural phenomenon in which stormwater from upper Cypress Creek leaves the watershed and flows overland (south) into the Addicks Reservoir watershed. This overflow was occurring before there was any development in the watershed, and is due to the natural topography of the area.
https://www.hcfcd.org/Find-Your-Watershed/Cypress-Creek/Cypress-Creek-Overflow-Management-Plan

Is a third reservoir planned for, and could it help the Cypress Creek watershed?

The answer depends on what is meant by a “third reservoir,” as there are several different reservoir options under discussion, with different goals. Depending on the option, a “third reservoir” would not necessarily address flooding issues in the Cypress Creek watershed.

Most often, talk of a “third reservoir” refers to a third reservoir on the west side of Harris County (not necessarily located in the Cypress Creek watershed) that could be added into the existing Addicks and Barker federal reservoir system, which is owned, operated and maintained by the U.S. Army Corps of Engineers.

The purpose of this third reservoir option would be to allow the federal reservoir system to handle more stormwater. It is intended to address the natural overflow from upper Cypress Creek into the Addicks Reservoir watershed. It would not necessarily reduce flooding risks downstream along Cypress Creek because that overflow is already leaving the Cypress Creek watershed. It also would not INCREASE flooding risks along Cypress Creek, because the overflow would continue to leave the watershed.

Various study efforts by the Flood Control District and others have examined components that could allow the reservoir systems to handle more stormwater. These studies include the Cypress Creek Overflow Management Study and a 1940 study by the Corps.

The Galveston District of the U.S. Army Corps of Engineers is currently working on the Buffalo Bayou and Tributaries Resiliency Study. This study will consider the third reservoir option, as well as other options such as increasing storage within the existing reservoirs, through buyouts of the pool fringe areas.

The Flood Control District is coordinating with the Corps on this study.

Also, Bond Project F-56 is intended to study ways to manage the overflow of stormwater from the Cypress Creek watershed to the Addicks Reservoir watershed. It will not have an impact downstream along Cypress Creek.

Additional reservoirs in various locations also have been discussed in neighboring counties and municipalities, most notably in Montgomery County on the San Jacinto River and Spring Creek.

Is a barrier or levee being proposed south of Cypress Creek to prevent overflow into the Addicks Reservoir?

The Galveston District of the U.S. Army Corps of Engineers is currently working on the Buffalo Bayou and Tributaries Resiliency Study. None of the measures being considered include a barrier or levee to re-direct the Cypress Creek overflow stormwater back into Cypress Creek. The original 1940 plan did show a levee to prevent the Cypress Creek overflow. The levee was feasible in 1940, before the area was developed, but is not feasible today because it would cause downstream impacts.

Also, Harris County Flood Control District Bond Project F-56 is intended to study ways to manage the overflow of stormwater from the Cypress Creek watershed to the Addicks Reservoir watershed. It will not have an impact downstream along Cypress Creek.

Are pumping stations an efficient way to increase storage volume in stormwater detention basins?

The Flood Control District typically does not utilize pumps in our stormwater detention basins because of the vastly increased operations and maintenance costs associated with pump stations, as well as the risk of failure.

The Flood Control District will not rule out using pump stations in unique circumstances where the benefits provided by pumping a stormwater detention basin dry via pumps will greatly exceed the additional maintenance costs associated with the pump stations.

Municipal Utility Districts can design, construct and maintain pump stations on the basins that they own and maintain.

What about pumping stormwater into underlying aquifers?

We are aware of the managed aquifer recharge technology, which includes the use of stormwater injection wells and infiltration ponds. While an ongoing feasibility study will look at multiple potential benefits of MAR technology, the Flood Control District is especially interested is determining whether this technology could be a safe and cost-effective tool for managing stormwater and reducing flooding risks in the Harris County region.

What is the “priority list” for the 2018 Bond Program and how does it impact Cypress Creek projects?

More than 200 projects are part of the 2018 Bond Program, and many of those projects – including ALL in the Cypress Creek watershed -- already have been initiated and are underway. For projects that have not already been initiated, the Flood Control District developed a prioritization framework that uses evaluation criteria and a weighting process to create a schedule for those projects throughout the remaining lifetime of the Bond Program.

Only two projects in the Cypress Creek watershed are ranked in the new prioritization framework. Both have already been initiated.

F-88 Design and Construction of Stormwater Detention Basins in Large Buyout Areas is ranked in the top quartile (1)

F-20 Cypress Creek Right-of-Way Acquisition and Floodplain Preservation is ranked in the second quartile (2).

No Cypress Creek projects will be delayed as a result of the priority framework.

Is subsidence making flooding worse in the Cypress Creek watershed?

No. The effects of subsidence have been studied, with the findings revealing that subsidence occurs in northern Harris County over wide areas. Because subsidence rates are fairly uniform across the Cypress Creek watershed, they wouldn’t result in changes in the flow carrying capacity of the stream. Small and relatively uniform decreases in elevation due to subsidence don’t change the fact that most parts of the Cypress Creek watershed continue to sit at well over 100 feet, which remains significantly higher than Galveston Bay where the watershed drains.