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.