How the Dryline Score is computed.
One 0–100 number per Texas address. Five public-data subscores, equally weighted. Every threshold is disclosed below. Higher score = more water stress.
Why a single number.
Reductive on purpose. The Dryline Score is the lede — the part that travels in a screenshot, a tweet, a real-estate listing. The cited synthesis below the score is the substance. The score exists to get the reader to read the substance.
We are aware of the criticism leveled at single-number climate-risk scores — Bloomberg ran a piece in late 2025 on the limits of climate-risk modeling, and Zillow notably pulled climate scores from listings. We take that seriously. The Dryline Score is built to be cited *alongside* this page, not in place of it: every threshold is on this page, every input is in the cited synthesis, every source has a retrieval timestamp.
The five subscores.
Each subscore is bounded 0–100. The Dryline Score is their integer mean. Subscores that cannot be computed (e.g. no monitoring well within range, no reservoir within 50 mi) default to 50 (neutral) and the rationale records the gap.
Drought
USDM ↗What's the current US Drought Monitor category for this county?
| None | → 0 |
| D0 (Abnormally Dry) | → 20 |
| D1 (Moderate) | → 40 |
| D2 (Severe) | → 60 |
| D3 (Extreme) | → 80 |
| D4 (Exceptional) | → 100 |
USDM is a county-coarse classification. Local conditions a few miles apart can vary materially; tree-and-fence drought is not the same as well-and-aquifer drought.
Aquifer
TWDB GWDB ↗What's the decadal depth-to-water trend at the nearest TWDB monitoring well?
| Rising or flat (≤ 0 ft/yr) | → 0 |
| 0.5 ft/yr falling | → 30 |
| 1.0 ft/yr falling | → 50 |
| 1.5 ft/yr falling | → 70 |
| 2.0+ ft/yr falling | → 90 |
A single monitoring well speaks for its hydrogeologic neighborhood, not the entire aquifer. Multi-decadal trend is a lagging signal; current pumping may be very different from what the trend implies.
Drinking water
EPA SDWIS ↗Are there current Safe Drinking Water Act violations at the primary public water system serving this address?
| Score = (H × 30) + (P × 10) + (R × 5) | → capped 0–100 |
Procedural violations (paperwork) and health-based violations (chemistry) are very different things; the score weights health-based heaviest but still surfaces procedural lapses. SDWIS underreports — EPA acknowledges the lag in their own documentation.
Industrial
EPA ECHO ↗How many federally-reportable individual NPDES dischargers are within 15 mi?
| 0 facilities | → 0 |
| 1 facility | → 20 |
| 2–3 facilities | → 40 |
| 4–6 facilities | → 60 |
| 7+ facilities | → 80 |
Permitted discharge ≠ illegal pollution. An individual NPDES permit means the facility is regulated and reporting, not that it's contaminating anything. The score reflects density of regulated industrial water use, not harm.
Reservoir
TWDB ↗How does the nearest instrumented reservoir compare to its same-day-of-year historical average?
| ≥ 1.05 (well above average) | → 0 |
| = 1.0 | → 20 |
| ≈ 0.85 | → 40 |
| ≈ 0.70 | → 60 |
| ≈ 0.55 | → 80 |
| < 0.40 | → 100 |
Surface reservoir status is one input to supply, not the whole picture. A property on groundwater is barely coupled to the nearest reservoir; a property in a coastal city tied to the Highland Lakes is very tightly coupled.
Composition.
score = round(mean(drought, aquifer, drinkingWater, industrial, reservoir))
Equal weights are a deliberate v0 choice. They are easy to audit and easy to argue with. A future revision may weight subscores by user-mode (Personal mode probably weighting drinking water + aquifer higher; Transparency mode weighting industrial + reservoir higher); when that ships, this page will version itself and the score component will display the methodology version it was computed under.
Bands.
Healthy aquifer trend, no current SDWA violations, reservoirs near or above average, no surrounding drought.
One or two subscores in the warning range. Typical for most of Texas in a normal year.
Multiple subscores in the high range. Drought + falling aquifer + concentrated industrial use is the canonical shape.
What the score is not.
- Not a property valuation. We do not recommend using it in lending or insurance underwriting; FCRA-adjacent obligations may apply and we have not done that work.
- Not a forecast. The score reflects the most recent published state of each data source. It does not project forward.
- Not a substitute for professional advice. For health questions, contact your utility or local TCEQ office. For legal questions, contact an attorney. For engineering questions (well drilling, rainwater capture), contact a Texas-licensed contractor.
- Not a measure of personal blame or property quality. It describes the hydrologic environment around the address, not the address itself.
See it run.
Every score on Dryline is computed from the same five subscores documented above, on the same public data, with every claim cited and every retrieval timestamped. Run an investigation and check the rationale strip below the score — it shows the exact value each subscore contributed and why.