Compare nutrient-source scenarios without hiding the unknowns.

Place already-derived nutrient mass loads on one common boundary and period, make unchanged and unquantified sources explicit, and inspect arithmetic differences without regulatory or treatment claims.

Inputs: User-supplied mass loads only
Data handling: Browser memory; explicit CSV export
Boundary: No TMDL, efficiency, target, or prescription

Guide · UnderstandReturn to the source guide

Shared route boundary

Does not calculate loads from monitoring inputs, TMDLs, allocations, efficiencies, targets, treatment prescriptions, rankings, causation, or guaranteed reductions.

Start with already-derived nutrient mass loads. Numeric fields are blank by design.

1 · Comparison scope

Keep one nutrient, boundary, period, and unit together.

Enter mass loads already derived under your project method. This tool does not derive loads from concentrations, flow, area, or coefficients.

Project titleRecord IDAnalyteExact reporting basisMass unitPeriod startPeriod endSpatial boundaryOverlap review

Analyte, basis, and unit lock after the first numeric entry so values cannot be silently reinterpreted.

2 · Baseline source ledger

Keep unknown and excluded sources visible.

Pathway presets organize entries only. They do not supply coefficients, efficiencies, or expected values.

Complete or correct these entries

Describe one spatial boundary for this ledger.
Enter both period dates.
Every source needs a descriptive label.
Each source: describe its boundary and possible overlap.

Source 1

Source labelPhysical pathwayBaseline stateEvidence basisBoundary and overlap note

3 · Action scenarios

State every changed, unchanged, and unknown source explicitly.

Scenario numbers remain user-supplied planning estimates. They are not predicted or guaranteed reductions.

Scenario to edit

Scenario nameScenario description

source-1Scenario stateReason

4 · Comparison ledger

Compare entered estimates without turning them into a prescription.

Overlap check incomplete. Source boundaries may overlap or double count loads. Review them before using the subtotal.

Complete the required context, evidence, and explicit scenario states to display comparable results.

Ledger notes

Field form · RecordOpen the source-control plan record
Preserve inventory, alternatives, authorization, and verification states with the scenario work.
Pathway · ContinueContinue the watershed restoration path
Move from scenario comparison into authorization, implementation, and effectiveness review.

Shared route boundary

Does not calculate loads from monitoring inputs, TMDLs, allocations, efficiencies, targets, treatment prescriptions, rankings, causation, or guaranteed reductions.

Method and sources

Arithmetic comparison, bounded interpretation.

The explorer sums only entered, already-derived source-load estimates. It calculates complete planning bounds only when every source has both bounds. Scenario-minus-baseline envelopes use scenario lower minus baseline upper and scenario upper minus baseline lower. These are arithmetic planning envelopes, not statistical confidence intervals or regulatory margins of safety.

EPA overview of Total Maximum Daily LoadsRegulatory functions deliberately excluded from this tool
EPA load-estimation guidance, Chapter 7Monitoring-design and load-estimation context
USGS methods for computing water-quality loadsMethod-selection context for externally derived inputs

Controlled preview. Internal technical review is complete. Independent review is pending, so this artifact remains available for review but is excluded from search-engine discovery. Next review: 2026-10-15.