How Our System Works

How Water Moves Through TID’s Current Hybrid System

Diversion (top of system)

  • Water is captured at the highest elevation
  • This elevation is what drives both pressure (pipe) and flow (ditch)
  • System needs a minimum of 120 CFS to run correctly at a 70% delivery rate

The Piped system is configured to use elevation at the top of the system to produce consistent delivery pressure

  • Water enters the pipeline first
  • Elevation drop creates usable pressure
  • Users in this zone get:
    • On-demand delivery (in most cases)
    • More consistent flow
    • Minimal conveyance loss

 Operational reality:
The pipe system captures the most efficient portion of the system hydraulics first

Remaining water transitions to ditch system

  • Water not used (or routed around pipe zones) continues downstream
  • Enters open ditch network
  • Begins to lose volume through:
    • Seepage
    • Operational spill
    • Transit inefficiencies

Ditch system distributes remaining supply

  • Delivery depends on:
    • Remaining flow
    • Gate settings
    • Physical condition of canals

 Operational reality:
Lower system is working with reduced and less controllable supply

  • More variability
  • More dependent on carry water
  • More losses before delivery
  • Surface delivery only

Where the Confusion Comes From

How the piped portion and the ditch portion physically affect each other because they are connected to the same water supply and elevation system.

The piped and ditch systems are hydraulically connected. What happens in the upper (piped) system directly affects how water arrives, behaves, and is available in the lower (ditch) system.

Operational Challenges in This System

1) Front-End Efficiency vs. Back-End Supply

  • Piping reduces losses upstream
  • But also reduces incidental return flows that historically fed lower ditches

Result:

  • Lower system may see:
    • Less “carry” water
    • Sharper shortages during peak demand

2) Perception of Priority

  • Piped users often experience:
    • Less visible shortage
  • Ditch users experience:
    • Gaps in delivery
    • Delivery delays- velocity of water- re-wetting of ditches, and vegetation

 Result:

  • Strong perception that pipe users are being favored, even when allocation policy is unchanged

3) Hydraulic Control Mismatch

  • Pipe system = controlled, pressurized, measurable
  • Ditch system = variable, manual, loss-prone

 Result:

  • Two fundamentally different service levels inside one district

4) Timing Conflicts

  • Pipe users may draw water continuously
  • Ditch users rely on remaining water availability

 Result:

  • Continuous upstream demand can flatten or delay downstream delivery.

5) Reduced Operational Flexibility

  • Open ditch systems historically relied on:
    • Spill
    • Seepage
    • Reuse flows
  • Piping removes much of that “flex”

 Result:

  • System becomes more efficient but less forgiving

6) Peak Demand Amplification

  • During hot periods:
    • Pipe users increase demand (sprinklers are running longer)
    • Ditch users need more water to receive their allocation

 Result:

  • System stress increases disproportionately at the lower end

7) Measurement Gap Between Systems

  • Pipe system:
    • Often metered or measurable
  • Ditch system:
    • Often estimated

 Result:

  • Hard to demonstrate equity across the two systems

8) Infrastructure Transition Effects

  • As piping increases:
    • Flow patterns change
    • Historic delivery assumptions no longer hold

 Result:

  • Lower system may feel like it is getting “left behind” during transition phases

Key Operational Reality

A hybrid system does not behave like a single system—it behaves like two different delivery systems connected in series, where the upstream system directly affects the performance of the downstream system.

The upper system is driven by pressure and efficiency. The lower system is driven by remaining supply and timing.

As we increase piping, we improve efficiency, but we also change how water arrives at the lower end.”

Managing this system is not just about allocation—it’s about balancing two fundamentally different delivery methods in real time.

 In a gravity-pressurized piped system, water delivery is more controlled and efficient than open ditch systems, but equity is still influenced by elevation, system design, and real-time demand on the network.

A gravity-pressurized pipe system does not create water. It preserves the water that would otherwise be lost in open conveyance and allows that water to be used for the open ditches.

Equity in an open ditch system must be actively managed within physical limits that do not distribute water uniformly.

Sincerely,

Chris Schull

District Manager