Saturday
Abuela had the comal on before Lourdes was up. When Lourdes came into the kitchen her grandmother was standing at the fridge in her housecoat with her reading glasses on, holding the printed screenshot flat with one finger, the way she held a recipe she didn't trust.
"Why is the boy's name on Benigno's roof?"
"Because a computer put it there."
"The boy never went to Benigno's."
"No. He stood on the church all night. The computer took his number and spread it sixty metres in every direction."
Abuela took a tortilla off the comal with her fingertips, turned it, and laid it back down. "Here it's hot," she said, tapping the middle of the iron. "Here," the rim, "warm." She pointed at the counter. "There, nothing. Nobody puts a tortilla on the counter and says it's cooking."
"That's it," Lourdes said. "That's the whole thing."
"So write down how far the heat goes."
Lourdes sat with her coffee. A certificate said where she'd stood, when, which head, which posts, the pier tie, the CAUSE line. It didn't say how far a post could see. Every notary in Maricopa knew the answer roughly, the way you know how far a voice carries in a parish hall. Nobody had ever put it in a field, because until Monday nobody had ever read a certificate from sixty metres away.
"You're right," she said.
"I know. Eat."
3/27 ABUELA: 'WRITE DOWN HOW FAR THE HEAT GOES.' CERTS SAY WHERE, NOT HOW FAR.
Sunday
Three o'clock, after Mass and the dishes. Father Ibarra had preached on the talents again, the servant who buried his in the ground, and she'd spent the homily thinking about how far down. Now: graph paper, a pencil, the 0402 manual open to the appendix nobody reads, and Abuela in the other chair shelling pecans into a bowl and pretending not to watch.
To a gravimeter, a layer of water under a lawn looks like a thin sheet. She wrote the rule the way she'd learned it at ASU. Seen from a height z above the sheet, the share of its pull that comes from inside a circle of radius r is one minus z over the square root of z squared plus r squared. Set that to ninety percent and r comes out at about ten times the depth.
The Ortiz wet front had sat between 1.2 and 1.8 metres all winter. Below the ground, though, not below the instrument. The 0402's sensor rode about three-tenths of a metre above the nail at her setup height, so the bottom of the front was 2.1 metres under the thing doing the reading. Ten times 2.1 is twenty-one. Ninety percent of anything post 3 had ever read came from within twenty-one metres of post 3. The deeper layer set it, too. The shallow edge of the front only pulled from twelve or fifteen metres out, but a radius has to hold for the water farthest down, or ninety percent isn't true.
Then she worked the realistic case, a compact pocket of water two metres down, read from sixty metres off to the side. The vertical pull falls with the cube of the slant distance. She did it on the calculator twice. From sixty metres away the pocket gave about four hundred-thousandths of what it gave from straight overhead. Fermín's +0.31 at post 1 was about seven millimetres of water at forty-two microgals per metre. From Benigno's carport, a head couldn't have found it.
The kernel had found +0.15 there.
She drafted the rule on the graph paper, under the arithmetic:
Item 6. Support. Each post shall state a support radius within which 90% of its tied residual originates, the residual being what remains after the pier tie under item 5. The radius is ten times the depth of the deepest water named in the CAUSE line, measured below the sensor at setup height. Where no depth is stated, or the series is UNTIED, support is UNDETERMINED and the series asserts nothing beyond the posts themselves. A certified series asserts nothing outside the union of its posts' support.
She'd written 20 m where no depth is stated first and crossed it out. Twenty metres assumed the water was within two. Perched water over a caliche lens, or a leak under a deep footing at six or eight metres, would push the true radius to sixty or eighty, and sixty was exactly the number the kernel used. A default would hand Desert Mutual its own figure back with her signature on it. No depth, no radius. And the tie had to come first. An untied series still carried the valley's whole decline, and that pull came from the entire basin, not from anything under the lawn. Somebody would read no radius stated on an untied certificate and call it a radius of the whole aquifer.
Abuela leaned over and looked at the graph paper, at the curve that dropped off a cliff and lay flat along the bottom of the page.
"That's the comal," she said.
"That's the comal."
"It's a short comal."
"Water close to the surface is a short comal. Deep water is a wide one. The deeper it is, the farther a post can feel it, and the weaker." She tapped the flat tail of the curve. "Benigno's carport is out here."
Abuela went back to her pecans. "Then they cooked his tortilla on the counter."
Then she opened the Records schema. support was already a field, reserved in 2041 and never used. Someone had thought of it once, and in eight years nobody had filled it in.
3/28 90% WITHIN ~10× DEPTH BELOW SENSOR, DEEPEST WATER, TIED RESIDUAL ONLY. ORTIZ 21 M. NO DEPTH OR UNTIED = UNDETERMINED. A 2 M POCKET AT 60 M ≈ 4×10⁻⁵ OF OVERHEAD. THE KERNEL'S +0.15 HAS NO PHYSICS UNDER IT.
Monday
Five past seven, the car outside Records on West Jefferson with the engine off. She wanted to see it before the counter opened and somebody asked her what she thought.
The bulk feed had gone live at seven. Every parcel in the valley had a tile now, and every tile had a Basis line. She filtered on #118.
Forty-one parcels. She checked each one against her own book. She had stood on nine. The other thirty-two were across alleys and over block walls from lots she'd occupied, some from surveys three years old. Thirty were MODERATE or LOW, and nobody would ever call her about those. Two were HIGH.
One of the HIGH tiles was on 36th Street, two lots east of the Leal house. She remembered the Leal job because of the cause. A cracked supply line under the slab, +2.4 µGal over the kitchen, CAUSE written, the line repaired that November with a plumber's receipt in the file. The Leal series recorded a leak that had been fixed seventeen months ago. The kernel had picked the leak up and laid it two lots east, on a house belonging to an R. Vega who, as far as Lourdes knew, had never had water anywhere it shouldn't be.
At 7:31 her phone buzzed. A number she didn't know.
Is this the notary 118? My insurance thing says my house is wet because of you. I don't know you. Rosalinda Vega.
She didn't answer from the parking lot. She wrote down the address and the date of the Leal repair, and went in when the doors opened.
Inside, there was already a line. Four notaries she knew by licence number and two she knew by face, all with phones out, all scrolling the same feed. #204 held his up so she could see it: sixty-seven parcels, eleven stood on. #231 had a HIGH on a daycare. Nobody said the word kernel. They said my name and her house and I never went there, and somebody near the front asked Ofelia, louder than he meant to, whether you could just pull a certificate.
3/29 FEED LIVE. #118 ON 41 PARCELS, STOOD ON 9. VEGA HIGH FROM LEAL '47, REPAIRED. R. VEGA 07:31. NOT YET.
Tuesday
Ofelia had the amendment form out before Lourdes reached the counter, so she'd been reading the feed too.
"People are starting to withdraw," Ofelia said. "Two yesterday. Pull the certificate and the name comes off the tiles."
That was the easy answer, and Lourdes had turned it over all night. If she withdrew the Leal series, #118 would come off Rosalinda Vega's house by lunch. It would also come off the Leal house, and with it the record of the leak, the repair, and the receipt. In ten years somebody would buy that house and never know there had been water under the kitchen. Withdrawing was how a notary lied by deleting. She'd spent February saying so to anyone who'd listen.
She said it now, in order, so Ofelia could put it in the book.
"I'm not withdrawing anything. I'm amending all nine. Six get a support radius under item 6, as drafted. Three of mine still say UNTIED, so those three get UNDETERMINED, which means they say nothing about anything past the nail until I tie them. Aguirre has it on 49-007 as of this morning. Leal gets a second line: Source repaired 11/2047, receipt in file. Series after repair: dry. Nothing in any series changes. I'm filling in the field that's been empty since 2041."
"And the thirty-two?"
"I write to them. One letter, the same for everyone, signed on the licence."
Ofelia slid the form across. "You don't have to do that."
"No."
She wrote it standing at the side shelf, in fewer words than she'd expected:
My certificate describes the lot I stood on, within the support radius stated on it. It does not describe your lot. Any score that uses it for your lot is not my measurement. If you want your lot measured, any licensed notary can survey it. I am not the right one, because my series is already on your tile.
Then she answered Rosalinda Vega with the same paragraph and one more line. The water was at the Leal house, two lots west, and it was fixed in November 2047.
Vega wrote back an hour later. So my house is fine?
That was the question, and the honest answer was smaller than the one Vega wanted. I don't know. Nobody has measured it. I only know my number isn't about it.
3/30 NO WITHDRAWALS. 9 AMENDED, 6 RADIUS, 3 UNDETERMINED. ITEM 6 TO AGUIRRE. LETTER TO 32. R. VEGA: 'SO MY HOUSE IS FINE?' I DON'T KNOW. NOBODY HAS STOOD ON IT.
Thursday
A quarter to six, the Food City lot again, as if Corinne Haas could only reach her near tortillas.
"We've seen the support field," Haas said. She sounded less hurried than last time. "Nine certificates with it filled on Tuesday. Twenty-three now. Fermín Robles did his an hour after yours."
"Good."
"Our modelling team wants to use it as a weight. Full weight inside the radius. Outside it, the kernel decays faster. It's a real improvement."
"It isn't a weight," Lourdes said. "It's a boundary. Outside the radius the certificate doesn't say something small. It doesn't say anything. If you decay it, you're still putting a number on a lot nobody measured, with my licence next to it."
A long pause. Haas was writing.
"Legal raised section 4 again," Haas said. "If we use a published field against its stated meaning, that's the argument you'd make. So the next release clips at the stated radius. Sixty days."
"And the parcels outside it?"
"They keep scores from the other inputs. SRP lateral schedules, permits, roof area. Not from certificates."
So that was the answer. Rosalinda Vega's tile would stay HIGH. Only the Basis line would change. Her house would still be wet in the model, and the model would stop saying a notary had stood there and found it so.
Lourdes asked herself whether that was a win. It was what she'd asked for. A colour on a house she had never stood on wasn't hers to fix. All she could do was stop signing it.
"Thank you," she said. She meant it, and she minded a little that she meant it.
"Off the record," Haas said. "How did you think of it? The radius."
"My grandmother's comal."
Haas laughed, unsure what the joke was, and hung up.
She drove home the long way, down 36th Street, because she wanted to know what the house looked like and because she had told herself she wouldn't.
It was a block ranch like the Leal house, painted the green of a hospital wall a long time ago, with a carport, a mesquite, and a strip of gravel where a lawn had been once. Nothing was wet. A woman about Abuela's age in a sun visor was watering three potted geraniums on the step with a measuring cup, a careful half cup each, the way you water when someone has told you water is the problem. She looked up at the slow car. Lourdes didn't stop. She was the one person in the county who had no business on that gravel with a head and a tripod, and she'd put that in writing on Tuesday.
She parked in her own drive and sat with the engine off and the bag of tortillas warm on the passenger seat. In sixty days her name would come off thirty-two roofs. The colour would stay on two of them. Somewhere on 36th Street a woman would get a renewal notice that said nothing about notaries at all, and she'd have nobody to text.
She wrote the card on her knee.
4/1 HAAS: 23 CERTS WITH SUPPORT. WANTED A WEIGHT. TOLD HER BOUNDARY. CLIP AT RADIUS IN 60 DAYS. VEGA STAYS HIGH WITHOUT MY NAME.
Then, smaller, under it:
I CAN STOP SIGNING IT. I CAN'T MAKE IT TRUE.