---
title: a lot is not a home until the water is promised
canonical_url: https://ensurance.app/guide/a-lot-is-not-a-home-until-the-water-is-promised
markdown_url: https://ensurance.app/guide/a-lot-is-not-a-home-until-the-water-is-promised.md
subtitle: "what Arizona's 2023 pause showed every developer about the aquifer under the plan"
category: natural-capital
---

# a lot is not a home until the water is promised

*what Arizona's 2023 pause showed every developer about the aquifer under the plan*

**What is an assured water supply?** As the Kyl Center for Water Policy at Arizona State University described it in June 2023, an assured water supply in Arizona's Active Management Areas (AMAs) is a finding by the Arizona Department of Water Resources (ADWR) that enough water of adequate quality will be physically, legally and continuously available for at least 100 years. A developer outside a designated water provider's service area needed one before selling lots in a new subdivision.

On June 1, 2023, Governor Katie Hobbs and ADWR released a new groundwater model for the Phoenix AMA. It projected 4.86 million acre-feet of unmet groundwater demand over 100 years (an acre-foot is roughly enough for two to three US households a year, per Fox 10), which the governor described as a possible 4% shortfall in groundwater supplies over 100 years if nothing changed. The state paused approval of new assured water supply determinations that rely on pumping groundwater in the Phoenix AMA. Construction did not stop, and about 80,000 lots that already held certificates were not affected. What stopped was one path: proving a new subdivision's hundred years on local groundwater.

The aquifer under the Phoenix area, and the rivers that feed its cities, were holding and carrying water long before the first lot was platted, and they do that work whether or not anyone pays. A subdivision depends on them, and so do the farms, towns and industries around it. **[ensurance](/explore?from=guide)** gives a living place an account so the ones who depend on it can pay for its keeping. The account is not the aquifer, and adds no water to it.

*This post explains a public rule and a dated event. It is not legal, insurance or tax advice.*

## what an assured water supply is, test by test

The rule comes from Arizona's 1980 Groundwater Management Act. As the Arizona Municipal Water Users Association (AMWUA) and the Kyl Center described it in 2019 and 2023, ADWR has to find that the water is there before a subdivision's lots can be sold. AMWUA states the purpose plainly: to protect homebuyers from learning, after they move in, that the water has run out.

| test | what ADWR looks for |
|---|---|
| **Physical** | Water available for 100 years; for groundwater, pumping may not dry existing wells or let the aquifer fall lower than 1,000 feet below the ground surface |
| **Legal** | A commitment from a recognized provider, such as a city, town or private water company |
| **Continuous** | Storage, drought plans and backup supplies |
| **Quality** | Water that meets state and federal standards |
| **Management goal** | Use consistent with the AMA's management plan and its goal of safe yield, a balance between the groundwater pumped and the water put back; AMWUA says a designated provider shows this by using renewable supplies, such as Salt River Project river water or Central Arizona Project Colorado River water, instead of relying on groundwater |
| **Financial** | The means to build and keep up the facilities that treat and deliver the water |

A city, town or private water company can hold a **designation**, covering current, committed and future uses in its service area. According to the Kyl Center, ADWR had designated 15 providers in the Phoenix AMA, including Phoenix and all of its large cities, and reviews each at least every 15 years, so the hundred years rolls forward. Outside those service areas, a developer of six or more lots must obtain a **certificate** for the subdivision itself.

## june 2023: what paused and what did not

The Kyl Center's June 2023 explainer put it plainly: all of the physically available groundwater in the Greater Phoenix area is fully allocated.

| | after June 1, 2023 |
|---|---|
| **New certificates based on local groundwater** | Paused in the Phoenix AMA |
| **About 80,000 lots already certified** | Not affected while the approved plat stands; existing certificates were not rescinded |
| **The 15 designated providers** | Little affected; they could keep serving new subdivisions, apartments and industry |
| **Buckeye and Queen Creek** | High-growth communities without a designation, among the areas affected |
| **Subdivisions using water other than local groundwater** | Still able to apply |
| **Construction** | Not suspended; no moratorium was ordered |

The Kyl Center read the result as the 1980 law working as intended. Developers had often preferred less expensive land outside designated service areas, where a certificate could rest on unallocated groundwater. After the model, there was none left to allocate.

In 2025 the governor signed SB 1611, the "ag-to-urban" bill, which lets farmers sell farmland and groundwater rights to housing developers; Fox 10 Phoenix reported it as an alternative path for places such as Queen Creek. This post does not say what the rule is today. ADWR does.

## the trap: a plan that stops at the plat

A land plan scores the parcel. The water the finding turned on was not inside the boundary. It was below ground, drawn on by every other existing and permitted use the model counted, and counted in one model covering the Hassayampa and the East and West Salt River Valley sub-basins together.

A lot is not a home until the water is promised for a hundred years. The promise is a document; what it promises is a living system the developer does not own and cannot see from the site.

None of this faults those who planned on groundwater under a rule in place since 1980. The model counted committed demand against the water physically there, before the homes were sold.

## gray and natural sources on one desk

**Gray, already billed:** the provider's wells and treatment plants; the Central Arizona Project (CAP) canal, which brings Colorado River water into central Arizona; reclaimed-water plants; and underground storage where providers bank water. A developer pays for these in fees, rates or the cost of a new supply.

**Natural, unbilled for their keeping:** the aquifer itself, which AMWUA calls finite, effectively gone once pumped; the Colorado River basin behind the canal, which the Kyl Center describes as overallocated and under the stress of a changing climate; and the Salt and Verde rivers in the designated cities' supply. This is **natural infrastructure**: it helps hold and deliver the water the gray system moves.

The same aquifer serves every subdivision, farm, town and factory that pumps from it. That is why one model run reached a whole market at once, and why its keeping could be shared. The chain runs three links: the aquifer and the rivers, then the subdivision, then the families who will live there and the town that will serve them, as [what you depend on](/guide/what-you-depend-on?from=guide) traces for any account.

## hold both

Keeping an aquifer mostly means drawing on it less and putting water back where possible. Nothing here claims that a better-kept aquifer would have changed the 2023 finding. The claim is narrower: what stopped new certificates was a shared source outside the property line, one that no one bills for its keeping, and keeping that source is part of the developer's own risk work, beside the gray supply, not instead of it.

Ensurance is built to give a place like this an account, so those who depend on the water can fund its keeping. The [Colorado River](/colorado-river.basin?from=guide) has an account, as do the [water abundance](/water-abundance.ensurance?from=guide) coin and the [water cycle](/water-cycle.syndicate?from=guide) syndicate. The Phoenix AMA aquifer has no account of its own yet; it can be [suggested and co-created under the Colorado River](/specific/create?mode=suggest&agent=colorado-river.basin&name=Phoenix%20AMA%20aquifer&from=guide), where it shows as coming soon.

:::johnson
**the plat is drawn on the surface. the promise is drawn on the water underneath and beyond it.** Every certificate counts on water its neighbors count on too. Put that source on the map before the next phase is drawn.

[see who else depends on the same water →](/guide/what-is-a-serviceshed?from=guide)
:::

## the bill and the source

| row | this event |
|---|---|
| **The property** | A proposed subdivision in the Phoenix AMA, outside a designated provider's service area |
| **The source** | Groundwater in the Phoenix AMA sub-basins, with the Colorado, Salt and Verde rivers behind the designated cities' supplies |
| **Which bill it landed on** | Protected earnings (lots unsold without a certificate) and avoided capital spend (water other than local groundwater); see [what ensurance saves you](/guide/what-ensurance-saves-you?from=guide) |
| **Who else leaned on the same source** | The existing and permitted uses the model counted: certified lots, cities, farms and industry |
| **What keeping it looks like** | Work the Kyl Center listed in June 2023 as past successes of central Arizona providers: conservation, reclaimed water, banking Colorado River and reclaimed water underground, and leases and exchanges between providers. Since 2025, a law that moves farm groundwater rights to housing, which the governor said protects groundwater |

What that keeping is worth, and the most each party should pay, is [what a source is worth paying for](/guide/what-a-source-is-worth-paying-for?from=guide).

## where to go next

Landowners and developers: [solutions for landowners](/solutions/landowners?from=guide&topic=outside-the-property-line). Investors and lenders: [solutions for investors](/solutions/investors?from=guide&topic=outside-the-property-line). Cities and counties: [solutions for governments](/solutions/governments?from=guide&topic=outside-the-property-line). Or [talk through the source under your own plan](/contact?from=guide&topic=outside-the-property-line).

## frequently asked questions

### what is an assured water supply?

In Arizona's Active Management Areas, as the Kyl Center described it in June 2023, it is an ADWR determination that enough water of adequate quality will be physically, legally and continuously available for at least 100 years, consistent with the area's management goal, with the finances to deliver it. Cities and water companies held designations; developers outside their service areas needed a certificate. Check ADWR for the rule as it stands now.

### did Arizona stop building in 2023?

No. In June 2023 the state paused new certificates based on local groundwater in the Phoenix AMA. Construction was not suspended, about 80,000 certified lots were unaffected, and designated cities kept serving growth. A 2025 law added another path. Buyers can start with [the water question every Phoenix homebuyer should ask](/guide/is-it-safe-to-buy-a-house-in-phoenix-water-shortage?from=guide).

### what can a developer do about a source it does not own?

Name the aquifer or river the plan depends on, who else draws on it, and what is already done to keep it. Then weigh a share of that keeping against the bill a shortfall would land on: [what a source is worth paying for](/guide/what-a-source-is-worth-paying-for?from=guide).

## sources

[Kyl Center for Water Policy, Arizona State University, "New Phoenix AMA Model Shows Limits of Groundwater as an Assured Water Supply," June 2023](https://morrisoninstitute.asu.edu/sites/default/files/kyl_center_phoenix_ama_groundwater_model_explainer_062023.pdf) — The 4.86 million acre-feet of unmet demand over 100 years, the definition, 15 designated providers, Buckeye and Queen Creek, six-lot subdivisions, 15-year reviews, the three sub-basins and existing adaptation work

[Fox 10 Phoenix, on the pause of groundwater-based water supply certificates, June 1, 2023](https://www.fox10phoenix.com/news/arizona-governor-pauses-water-supply-certificates) — The governor's conditional 4% shortfall quote, the acre-foot gloss, and the pause on certificates that rely on groundwater

[Quarles & Brady, "Combating Misperception: Arizona Is Not Out Of Water; Construction Has Not Been Suspended," June 8, 2023](https://www.quarles.com/newsroom/publications/combating-misperception-arizona-is-not-out-of-water-construction-has-not-been-suspended) — About 80,000 certified lots unaffected, existing certificates not rescinded, the material plat change caveat, no construction moratorium, and the designated cities

[Arizona Municipal Water Users Association, blog on the Assured Water Supply Program, April 1, 2019](https://www.amwua.org/blog/assured-water-supply-program-protecting-homebuyers-while-ensuring-responsible-growth) — The 1980 Groundwater Management Act, the tests, safe yield, the 1,000-foot limit, protecting homebuyers, and groundwater as a finite supply

[Fox 10 Phoenix, on the signing of the ag-to-urban bill, July 2025](https://www.fox10phoenix.com/news/ag-to-urban-gov-katie-hobbs-signs-water-bill) — SB 1611 lets farmers sell farmland and groundwater rights to housing developers as an alternative path, and the governor's statement that it protects groundwater

## the series

1. [the loss started outside the property line](/guide/the-loss-started-outside-the-property-line?from=guide) — **read first:** one flooded factory, and every hospital that depends on it
2. [a hospital cannot store a watershed](/guide/a-hospital-cannot-store-a-watershed?from=guide) — fifty-four days on tanker trucks
3. [a chip fab still waits for rain](/guide/a-chip-fab-still-waits-for-rain?from=guide) — the year no typhoon reached Taiwan
4. [the factory was sound. the floodplain was full](/guide/the-factory-was-sound-the-floodplain-was-full?from=guide) — the 2011 Thailand floods and the ground under a lease
5. [the office park stands where the marsh was](/guide/the-office-park-stands-where-the-marsh-was?from=guide) — Chennai's 2015 flood and the shutdowns no policy covered
6. [a lot is not a home until the water is promised](/guide/a-lot-is-not-a-home-until-the-water-is-promised?from=guide) — this post
7. [the resort never owned the trees](/guide/the-resort-never-owned-the-trees?from=guide) — a ski area, a national forest, and the season a wildfire took
8. [every ship spends water the forest gathered](/guide/every-ship-spends-water-the-forest-gathered?from=guide) — the Panama Canal's dry year
9. [what a source is worth paying for](/guide/what-a-source-is-worth-paying-for?from=guide) — how an avoided loss becomes the most you should pay
10. [how to map what your property depends on](/guide/how-to-map-what-your-property-depends-on?from=guide) — draw the map one ring wider than the deed