Harris County moves forward with $597M Cypress Creek detention basins (2024)

As hurricane season nears, the Harris County Flood Control District is making progress on stormwater detention basins planned for the Cypress Creek watershed.

The 2021 Cypress Creek Implementation Plan recommended 22 basins as a flood risk reduction strategy. While the $1.4 million study was covered by the $2.5 billion HCFCD bond voters approved in 2018, the projects recommended were not.

Construction is underway on basins in the eastern part of the watershed near I-45, but the HCFCD must secure funding before others break ground.

“We’ve been able to get started on a few of those, but the reality is there’s not funding to do all of those,” HCFCD Grants Administrator Jonathan St. Romain said.

The big picture

Building stormwater detention basins includes a feasibility study; preliminary engineering; right-of-way acquisition and utility relocation; design; and construction. Funding procurement happens through each step, HCFCD officials said.

“Unfortunately, once you identify a project, it takes many years from the time you say ‘we want to do a project’ until you get it funded, until you get it studied, until you get it refined, until you get it put in the ground,” Harris County Precinct 3 Commissioner Tom Ramsey said.

Projects in the plan are prioritized based on land acquisition, potential flood risk reduction and available funding, St. Romain said.

Engineering and consulting firm Michael Baker International released the Cypress Creek Watershed Major Tributaries Regional Drainage Plan in February 2020, which recommended 56,500 acre-feet, or 18.41 billion gallons, of stormwater detention to mitigate flooding from Little Cypress Creek and Cypress Creek.

The Cypress Creek Implementation Plan, which was released in November 2021, identified specific projects that could bring 14,000 acre-feet, or 4.56 billion gallons, of stormwater storage volume to the Cypress Creek watershed—about 25% of what was recommended. According to the study, this would remove 19% of structures from the watershed’s 100-year flood plain and cost nearly $600 million.

Alan Black formerly worked for the HCFCD and is now vice president of Quiddity Engineering, the firm that conducted the implementation plan. He said, since 1937, the HCFCD has excavated about 63,000 acre-feet countywide.

“It will take decades to get to that 19%,” he said at the Cypress Creek Drainage Improvement District’s April 16 town hall meeting.

1. Mercer Stormwater Detention Basin

  • Funding: $15.4 million grant through the Community Development Block Grant-Disaster Recovery program
  • Status: under construction December 2023-fourth quarter of 2024

2. TC Jester Stormwater Detention Basins (Phase 1)

  • Funding: $9.95 million in federal community-directed funding; $3.3 million in 2018 bond program funding
  • Status: construction to begin in late 2024

3. TC Jester Stormwater Detention Basins (Phase 2)

  • Funding: $35 million in CDBG funding; $12 million from state community-directed funding
  • Status: in the design phase and advertising for bids in third quarter of 2024; construction to last 24 months

4. Westador Stormwater Detention Basin

  • Funding: $8.25 million in federal funding
  • Status: construction to begin in early 2025

Funding the project

HCFCD officials said the 2018 bond program included $60 million for maintenance work along Cypress Creek and $100 million for land acquisition and flood plain preservation. This funding has been used to purchase property for some stormwater detention basins, including the Cypress Park basin extension off North Eldridge Parkway and the Mercer basin off the Hardy Toll Road and FM 1960.

However, the district is seeking additional funding sources, such as state and federal grants, local partnerships and federal allocations, to continue this work. Each funding program comes with its own unique set of challenges, such as environmental studies, socioeconomic factors and expiration dates, St. Romain said.

“The 2018 bond program was designed to be a starting point for broader flood resilience efforts, and we acknowledged from the outset that it would not cover all needs,” St. Romain said.

In upcoming county budget discussions, Ramsey said he will be advocating for more funding for HCFCD and the Cypress Creek watershed. He noted addressing deferred maintenance and getting bond projects to construction as top priorities.

“Cypress Creek is the largest watershed in the county and it’s probably the most underfunded watershed in the precinct,” Ramsey said.

Ahead of the 89th Texas Legislature, the newly-created Cypress Creek Drainage Improvement District is also working to advocate for the watershed by hosting town hall meetings and collecting feedback to identify priority projects.

“To address flooding along Cypress Creek really requires the federal government, state government [and] county government to be involved—that is not something that Harris County can do by itself. You can’t have that many bond elections,” district President Calvin Cobb said.

Since the 2018 bond program was approved:

  • $156 million has been spent on Cypress Creek projects.
  • $92 million has been spent on Little Cypress Creek projects.
  • 175 voluntary home buyouts have been completed in the Cypress Creek watershed.
  • 22 detention basins have been recommended for the watershed for more than $597 million.

What to expect

The HCFCD is in the preliminary stages of scoping a new study—Solutions for Adaptive Flood Mitigation Equitably Empowering Resilient Communities, or SAFER—which will help officials understand the feasibility and impacts of underground stormwater tunnels across the county, potentially including in the Cypress Creek watershed.

In Spring, construction began in late 2023 on the Mercer Stormwater Detention Basin. HCFCD also plans to break ground on Phase 1 of the TC Jester Stormwater Detention Basins and the Westador Stormwater Detention Basin in late 2024 and early 2025, respectively.

“Within the precinct, we’ve got 31 projects under construction today [and] we’re going to be adding another nine in the next month or so, so at least in Precinct 3, we are getting projects built,” Ramsey said.

Meanwhile, the flood control district is focused on completing the 2018 bond program and administering more than $825 million in federal grant funding. This funding, along with future partnership funds, will be spent on projects over the next several years.

“I think most everybody agrees that [HCFCD] projects to build detention basins—that was a good first step. Harris County owned a lot of the land along the creek where you could build these detention basins ... and clearly one of the key strategies of mitigating flooding is to add temporary storage where we can put the water,” Cobb said. “But everybody also recognizes that will not solve all of the problems.”

Harris County moves forward with $597M Cypress Creek detention basins (2024)

FAQs

How do detention basins work? ›

The ponds help manage the excess urban runoff generated by newly constructed impervious surfaces such as roads, parking lots and rooftops. A basin functions by allowing large flows of water to enter but limits the outflow by having a small opening at the lowest point of the structure.

What is an extended detention basin? ›

Definition. Extended detention basins are designed to receive and detain storm water runoff for a prolonged period of time, typically up to 48 hours.

What are the problems with detention basins? ›

Detention ponds are generally ineffective at removing pollutants in runoff because they do not provide adequate holding time for solids to settle before water is released into a stream or storm sewer system.

What are the pros and cons of detention basins? ›

Advantages and Disadvantages

They do effectively reduce peak rate and volume to pre-development rates when located and designed properly. Their disadvantages are that they are solutions to a single problem instead of multiple problems.

What is the difference between a retention pond and a detention basin? ›

A detention basin/pond temporarily stores stormwater runoff. The basin is designed to manage stormwater runoff by storing it and releasing it gradually until completed drained. Unlike a detention basin, a retention basin or pond is designed to permanently hold water.

How is the size of a detention basin determined? ›

The primary design parameter for sizing Detention Basins is the water quality volume (WQV). The WQV, or portion thereof, is equal to the minimum volume of the Detention Basin, which does not include any additional volume due to overflow events and freeboard.

What is the difference between a detention basin and an infiltration basin? ›

A detention basin slows the flow before releasing it into a smaller outlet. An infiltration basin operates much like a detention basin, but it is designed to infiltrate runoff into permeable soil.

How long should water stay in a detention pond? ›

To allow for enough settling time, the pond should be large enough to detain the volume of stormwater it treats for between 12 and 48 hours.

How long does it take for a detention basin to draw down? ›

24 hours (minimum) to draw down (completely dewater) the lower stage of the basin (equal to prescribed water quality volume). A more conservative design is to provide for draw down of approximately half of the volume in the first 24 hours, with the remaining volume dewatered within an additional 24 to 48 hours.

How does a detention tank work? ›

Detention tank: Detention tanks work by temporarily storing stormwater runoff during a rainfall event and then slowly releases the water into the public stormwater system. These can be located either above or below ground.

How do underground detention systems work? ›

How do underground detention systems actually work? The broad, overarching answer is through a series of collection points such as roofs, inlets, catch basins, swales, etc., water is directed structurally to a series of underground pipes or arched chambers or tanks.

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