7/2/26 – Political fragmentation can increase flood risk many ways. It is one of the least appreciated, but most significant factors in flooding – particularly in rapidly urbanizing watersheds like the San Jacinto River Basin.

Floodwater doesn’t respect jurisdictional boundaries. When many different jurisdictions make drainage decisions independently, it rarely, if ever, optimizes results. Here are 10 reasons why.

1. Upstream Communities Often Don’t Bear Downstream Costs They Create

A city or county may approve new development because it receives the tax revenue while the flood impacts occur miles away. For example:

• Community A approves thousands of acres of development.
• Runoff increases.
• The additional water flows into Community B.
• Community B pays for larger channels, detention basins, buyouts, and disaster recovery.

The economic incentives are misaligned. Individual interest trumps wider interest.

2. Different Regulations Create Weak Links

When designing flood infrastructure, one county may require:

• Atlas 14 rainfall
• Generous detention
• “No net fill” in floodplains
• Stricter erosion controls.

But a neighboring county may require much less.

Developers naturally gravitate toward the least restrictive jurisdiction.

The result is that runoff is generated where regulation is weakest. But that affects everyone downstream.

This has long been an issue between portions of rapidly growing counties surrounding Houston, where drainage criteria have historically differed.

3. Development is Approved One Project at a Time

Each subdivision may demonstrate “No adverse impact from this development.” And that may be technically true for that individual project. But no one evaluates:

• 500 developments together
• Cumulative increases in runoff
• Synchronized flood peaks stacking on top of each other
• Long-term watershed change.

Thousands of individually compliant projects can collectively overwhelm streams.

This is sometimes called the “Death by a Thousand Cuts” problem.

4. Transportation Agencies Optimize Roads – Not Watersheds

Road departments may prioritize:

• Minimizing bridge costs
• Minimizing culvert costs
• Reducing construction expenses.

Flood managers may want:

• Larger openings under bridges
• Fewer hydraulic bottlenecks
• Preservation of natural floodways.

If transportation and flood agencies are not coordinated, roads can become unintended dams during major floods.

5. Reservoir Operators May Have Different Missions

Sub-watersheds often include reservoirs managed by different organizations and/or for different purposes. For instance, one reservoir may prioritize water supply while another prioritizes flood control or recreation.

Without coordinated operating plans, releases can unintentionally compound downstream flooding. This has been discussed extensively regarding operations of Lake Conroe and Lake Houston, where coordinated releases can substantially influence downstream flood peaks.

6. Funding Responsibilities are Fragmented

One agency may pay for channel improvements, while others pay for maintenance, detention, environmental mitigation, and/or emergency response.

Projects that benefit everyone may stall because no single organization is responsible for paying for them. Coordination among agencies with different staffing, funding, and priorities can delay projects years. Economists call this a “collective action problem.”

For instance, according to Harris County Flood Control District (HCFCD), only half of the Taylor Gully/Woodridge project has started because the Texas Water Development Board has reportedly not yet approved the Taylor Gully portion.

Meanwhile, a critical HUD funding deadline is fast approaching that may cost Harris County hundreds of millions of dollars. It’s an HCFCD project. But City of Houston bridges are involved.

Aligning all these dominos takes years, especially when they involve grants from multiple agencies.

7. Floodplain Mapping Evolves at Different Speeds

One jurisdiction may adopt updated flood maps quickly while a neighboring jurisdiction may continue using older maps.

This means development can continue under outdated assumptions upstream while downstream communities build to newer, more conservative standards.

Again, the Taylor Gully/Woodridge project provides an excellent example. HCFCD contractors are now excavating dirt for a Woodridge Detention Basin. Some of that dirt is being hauled to a new development along Dry Creek at FM1485 in Montgomery County.

Technically, the dirt is being deposited outside the 100-year floodplain at that location, per HCFCD standards. But the Montgomery County floodplain map is still based on pre-Harvey (2014) data.

Are we paying to solve a flood problem…or to relocate it?

8. Data are Often Not Shared

As we saw above, jurisdictions frequently use different:

• Hydraulic models
• Rainfall assumptions
• LiDAR vintages
• Land-use projections
• Software platforms

When models don’t align across jurisdictional boundaries, flood analyses can become inconsistent.

9. Maintenance Responsibilities are Divided

Who:

• Removes sediment?
• Clears fallen trees?
• Maintains detention ponds?
• Repairs eroded channels?

If responsibility changes repeatedly across political boundaries, maintenance gaps develop that reduce channel capacity.

10. Emergency Response Becomes Harder

During large floods:

• Counties
• Cities
• Drainage districts
• River authorities
• State agencies
• Federal agencies

…must all coordinate their activities.

If communication is poor, evacuations, road closures, reservoir operations, and recovery efforts become less efficient.

The Cumulative Effect

Political fragmentation doesn’t usually create flooding by itself. Instead, it gradually amplifies flood risk by allowing many small decisions to accumulate or be deferred.

Fragmented decision	Watershed consequence
Different detention rules	More runoff
Different floodplain rules	More development in hazardous areas
Independent land-use decisions	Higher peak flows
Separate infrastructure planning	Hydraulic bottlenecks
Different maintenance standards	Reduced conveyance
Independent reservoir operations	Poorer timing of releases
Separate funding	Delayed mitigation projects

Each individual decision may appear reasonable within one jurisdiction. Collectively, they can increase both the frequency and severity of flooding across the river basin.

Why This Matters in the San Jacinto River Basin

The San Jacinto River watershed illustrates many of these challenges. It spans multiple counties and municipalities with varying drainage standards, development regulations, and infrastructure priorities.

Rapid upstream growth can alter runoff patterns that affect downstream communities, such as the Lake Houston Area. Indeed, it affects all of Houston and Harris County.

At the same time, reservoir operations, floodplain management, and mitigation investments are divided among numerous local, regional, state, and federal entities. Coordinating those decisions across jurisdictional boundaries is often as challenging as the engineering itself.

Many watershed professionals therefore advocate managing flood risk at the “watershed scale” rather than at the city or county scale.

That approach emphasizes common hydrologic assumptions, coordinated land-use planning, cumulative-impact analysis, shared data and models, aligned reservoir operations (where feasible), and funding mechanisms that reflect both where runoff is generated and where flood damages occur.

It does not eliminate flooding, but it can substantially reduce the extent to which fragmented governance makes floods worse.

In the 2025 Texas legislature, Representatives Paul, Cunningham, DeAyala, and Swanson authored a bill (HB2068) to expand HCFCD gradually throughout the river basin. However it was left pending in committee after HCFCD Executive Director Tina Petersen and Precinct 2 Commissioner Adrian Garcia testified against it. Let’s hope it can go farther next year with new leaders.

Posted by Bob Rehak on 7/3/2026 with the help of ChatGPT for research.

3230 Days since Hurricane Harvey