But what were they going to do with the water they pumped out? The southern highlands were everywhere lumpy, shattered, pocked, cracked, hillocky, scarped, slumped, fissured, and fractured; when analyzed as potential watersheds, they were hopeless. Nothing led anywhere; there was no downhill for long. The entire south was a plateau three to four kilometers above the old datum, with only local bumps and dips. Never had Nadia seen more clearly the difference between this highland and any continent on Earth. On Earth, tectonic movement had pushed up mountains every few-score million years, and then water had run down these fresh slopes, following the paths of least resistance back to the sea, carving the fractal vein patterns of watersheds everywhere. Even the dry basin regions on Earth were seamed with arroyos and dotted with playas. In the Martian south, however, the meteoric bombardment of the Noachian had hammered the land ferociously, leaving craters and ejecta everywhere; and then the battered irregular wasteland had lain there for two billion years under the ceaseless scouring of the dusty winds, tearing at every flaw. If they poured water onto this pummeled land they would end up with a crazy quilt of short streams, running down local inclines to the nearest rimless crater. Hardly any streams would make it to the sea in the north, or even into the Hellas or Argyre basins, both of which were ringed by mountain ranges of their own ejecta.

There were, however, a few exceptions to this situation. The Noachian Age had been followed by a brief “warm wet period” in the late Hesperian, a period perhaps as short as a hundred million years, when a thick warm CO₂ atmosphere had allowed liquid water to run on the surface, carving some river channels down the gentle tilts of the plateau, between crater aprons diverting them this way and that. And these watercourses had of course remained after the atmosphere had frozen out, empty arroyos gradually widened by the wind. These fossil riverbeds, like Nirgal Vallis, Warrego Valles, Protva Valles, Patana Valles, or Oltis Vallis, were narrow sinuous canyons, true riverine canyons rather than grabens or fossae. Some of them even had immature tributary systems. So efforts to design a macro-watershed system for the south naturally used these canyons as primary watercourses, with water pumped to the head of every tributary. Then there were also a number of old lava channels that could easily become rivers, as the lava, like the water, had tended to follow the path of least resistance downhill. And there were a number of tilted graben fractures and fissures, as at the foot of the Eridania Scopulus, that could likewise be turned to use.

In the conference, big globes of Mars were marked up daily to display different water regimes. There were also rooms full of 3-D topo maps, with groups standing around different watershed systems, arguing their advantages and disadvantages, or simply contemplating them, or fiddling with the controls to change them, restlessly, from one pattern to another. Nadia wandered the rooms looking at these hydrographies, learning much about the southern hemisphere that she had never known. There was a six-kilometer-high mountain near Richardson Crater, in the far south. The south polar cap itself was quite high. Dorsa Brevia, on the other hand, crossed a depression that looked like a ray cut out from the Hellas impact, a valley so deep that it ought to become a lake, an idea that the Dorsa Brevians naturally did not like. And certainly the area could be drained if they cared to do it. There were scores of variant plans, and every single system was strange looking to Nadia. Never had she seen so clearly how different a gravity-driven fractal was from impact randomness. In the inchoate meteoric landscape, almost anything was possible, because nothing was obvious — nothing except for the fact that in any possible system, some canals and tunnels would have to be built. Her new finger itched with the desire to get out there and run a bulldozer or a tunnel borer.

Gradually the most efficient, or logical, or aesthetically pleasing plans began to emerge from the proposals, the best for each region being patched together, in a kind of mosaic. In the eastern quadrant of the deep south, streams would tend to run toward Hellas Basin and through a couple of gorges into the Hellas Sea, which was fine. Dorsa Brevia accepted a plan to have their town’s lava tunnel ridge become a kind of dam, crossing a watershed transversely so that there was a lake above it and a river below it, coursing down to Hellas. Around the south polar cap, snowfall would remain frozen, but most of the meteorologists predicted that when things stabilized there wouldn’t be much snowfall on the pole, that it would become a cold desert like Antarctica. Eventually of course they would end up with a largish ice cap, and then part of it would pool down into the huge depression under the Promethei Rupes, another partially erased old impact basin. If they didn’t want too large of a southern ice cap, they would have to melt and pump some of the water back north, into the Hellas Sea perhaps. They would have to do some similar pumping in Argyre Basin, if they decided to keep Argyre dry. A group of moderate Red lawyers was even now insisting on this before the GEQ arguing that one of the two great dune-filled impact basins on the planet ought to be preserved. It seemed certain this claim would receive a favorable judgment from the court, and so all the watersheds around Argyre had to take this into account.

Sax had designed his own southern watershed plan, which he sent to the conference from their rocket as it aerobraked into orbital insertion, to be considered with all the rest. It minimized surface water, emptied most craters, used tunnels extensively, and channelized almost all drained water into the fossil river canyons. In his plan vast areas of the south would stay arid desert, making for a hemisphere of dry tableland, cut deeply by a few narrow river-bottomed canyons. “Water is returned north,” he explained to Nadia in a call, “and if you stay up on the plateaus, it will look like it always did, almost.”

So that Ann would like it, he was saying.

“Good idea,” Nadia said.

And indeed Sax’s plan was not that much different than the consensus being hammered out by the conference. Wet north, dry south; one more dualism to add to the great dichotomy. And to have the old river canyons running with water again was satisfying. A good-looking plan, given the terrain.

But the days were long gone when Sax or anyone else could choose a terraforming project and then go out and do it. Nadia could see that Sax hadn’t fully understood this. Ever since the beginning, when he had slipped algae-filled windmills into the field without the knowledge or approval of anyone but his accomplices, he had been working on his own. It was an ingrained habit of mind, and now he seemed to forget the review process that any watershed plan was going to have to go through in the environmental courts. But the process was there, inescapable now, and because of the grand gesture, half the fifty GEC justices were Reds of one shade or another. Any watershed proposal from a conference including Sax Russell, even as a teleparticipant, was going to get close and suspicious scrutiny.

But it seemed to Nadia that if the Red justices looked carefully at the proposal, they would have to be amazed at Sax’s approach. Indeed it represented a kind of road-to-Damascus conversion — inexplicable, given Sax’s history. Unless you knew all of it. But Nadia understood: he was trying to please Ann. Nadia doubted that was possible, but she liked to see Sax try. “A man full of surprises,” she remarked to Art.

“Brain trauma will do that.”

In any case, when the conference was done they had designed an entire hydrography, designating all the future major lakes and rivers and streams of the southern hemisphere. The plan would eventually have to be integrated with similar plans for the northern hemisphere, which were in considerable disarray by comparison, because of the uncertainty about just how big the northern sea was going to be. Water was no longer being actively pumped up out of permafrost and aquifers — indeed many of the pumping stations had been blown up in the last year by Red ecoteurs — but some water was still rising, under the weight put on the land by the water already pumped. And summer runoff was flowing into Vastitas, more every year, both from the northern polar cap and the Great Escarpment; Vastitas was the catchment basin for huge watersheds on all sides. So a lot of water was going to pour into it every summer. On the other hand, a lot of water was always being stripped off by the arid winds, eventually precipitating elsewhere. And water would evaporate much faster than the ice currently there was subliming. So calculating how much was leaving and how much coming back was a modeler’s field day, and estimates were still all over the map, literally so in that differences in prediction led to putative shorelines that were in some cases hundreds of kilometers apart.