How much Dust of Dryness to drain a swamp?

[Kyouhen]

Greetings!
So I've got my players on a job to protect a mining site from some pesky grung until the workers get the defenses set up. When they're done I want to offer the players a job to really get rid of the grung by draining the swamp. I'd like to do it with Dust of Dryness but am having a hard time figuring out how much is needed.
If I've got this right one pinch soaks 100 gallons of water, so a full pouch could soak 1,000. How big are these pouches? How much dust would fit in a barrel? How many gallons of water are in a small swamp? (That last one is the most relevant, having issues finding numbers for that.)
I know this is going to be brutally expensive, assume their employer has the resources and motivation to see this job done.
Thanks for any help!

[Tanarii]

Each pinch of dust of dryness turns about 25,000 gallons of water into a pearl. 15x15x15 ft, 7.48 gallons/cubic foot.

Of course, the adventurers have to grab it before the enemy does.

So (on average) 7.5*25000 gallons, or 187,500 gallons, per 400gp pouch. That might actually be more economical that just hiring a bunch of mercenaries at 2gp per day to kill the enemies.

[Contrast]

Firstly a swamp could be anything from 'slightly damp underfoot' to 'able to row a canoe around' which may be why you're finding it hard to find numbers.

Secondly a pinch of Dust turns a cube 15ft (~4.5m) on a side into a marble. That's 95.6m3 of water. Water has a density of 997kg/m3 so that's ~95000kg. So 95,000L or 20k-25k gallons (depending on if you're using UK or US gallons). Assuming perfect absorption anyway and the chances of that depend on what the swamp you're dealing with is like.

Plus you'd have to find somewhere to store/dispose of the pellets without breaking them...

Either way this is a bad idea because its a swamp because water drains into it - if you dry it out it'll just refill. This fits in that thread where a guy was asking for ideas a terrible mayor might have :smallbiggrin:

You're better off having them look to divert local streams or something. Or just...you know...kill the grung seeing as they will undoubtedly take offence at you trying to kill them all anyway.

[JackPhoenix]

Volume doesn't really matter. The swamp may or may not be 15' deep, but in either case, how many 15' squares would fit on its surface is more important. Of course, considering the short range, you'll have to deal with the grungs anyway, if you want to get rid of the whole swamp, and they are inside.

And there's the question of mud can be considered water enough for the dust to work.

[Kurt Kurageous]

Move Earth seems to be the answer you really really want. 4800sqft raised 20' up with every cast, taking 2 hours a cast.

Or an army of zombies/skeletons to dig a trench that redirects the water flowing into your swamp.



Dust of dryness? About as much sense as giving a bucket to my unseen servant.

[BlueHydra]

Some swamp druids are going to want to have a word with them.

[Unoriginal]

How would drying the swamp solve the Grung issue?

Now you have hostile beings who have even more reasons to give everything to destroy you.

[Raphite1]

Either way this is a bad idea because its a swamp because water drains into it - if you dry it out it'll just refill.

Yeah, it's this. ^^

If they want to permanently drain the swamp they'll have to do earthworks projects to change the geography. Depending on the location, this may mean creating a channel to drain the water into lower elevation areas (essentially turning the swamp into a stream), or it may mean building dikes to separate the swamp from an adjacent waterbody and then draining it.

If they just Dust of Dryness away the water without making any other changes, it'll be a swamp again in short order.

[Contrast]

How would drying the swamp solve the Grung issue?

Now you have hostile beings who have even more reasons to give everything to destroy you.

A grung who doesn't submerge themselves in water for at least an hour a day suffers a level of exhaustion. So theoretically if you instantly drained the swamp all the grung would be dead in a week.

It seems a perfect way to enrage them to attack you in the meantime of course and in practice its likely it would take much longer than a week to totally drain the swamp of all water, particularly given the grung would likely realise what was going on and make sure to store some water.

[GreyBlack]

Maybe it's just my inner Druid talking, but I'm now just dreading the ecological damage that would be done here. Like, think of all the dead fish/amphibians/whatnot that require the dampness of the swamp, to say nothing of the plants and animals...

[Kurt Kurageous]

I love campaigns that involve the planned genocide of sentient beings even more than plots that just involve the genocide of non-sentient beings.

This is some dark stuff. The swamp druids, the grungs, hell, everything's gonna be coming for that party!

And what if there are bullywugs?

[Karnitis]

So I always find the idea of genocide funny in a dark way (I know how that sounds) because I kind of want to see what happens the local population, the ecological impact, perhaps farther cities/towns that relied on X species for trade or resources.

Without any complex math, I figured I'd use something from neck of the woods. Okefenokee Swamp (in GA, USA) is described as a 'shallow' swamp, but may provide a base for you as it is still quite swampy (as anyone who visited could attest). If you are looking for something like the Florida Everglades, I agree that it would be literally impossible to Dust it to oblivion.

Now, Okefenokee is roughly 438,000 acres and average of (2-10) 6 ft deep. Now the dust works in a 15ft cube - the ft-height in negligible, since most of the swamp is only 10 ft deep max, but it would also absorb/dry up the water in the mud & peat, so it would thoroughly dry the depth of the swamp.

To solve for the length/width issue - googling 'how many cubit feet in an acre' pulls this up: It defined by the volume of water necessary to cover one acre of surface area to a depth of one foot. It is equal to exactly 43,560 cubic feet, or to 325,851 U.S. gallons, or exactly 1233.48184 cubic meters.

Convertunits.com says 438k acres = 19,079,280,194 cubic feet. That number, divided by 15 = 1,271,952,013 pinches of dryness dust. Dust of Dryness has 1d6+4 uses per packet. d6 average is 4, so 8 average uses per packet. Let's divide further, so that big number turns into 158,994,002 packets. Now, the bottom price for an 'uncommon' item is 101 gold, so...

I think I may have done my math wrong about cubit feet in an acre, so someone feel free to correct me. But it seems like using the Dust may not work. Sorry, a holocaust is probably off the table.

[Tanarii]

43560 sq ft in an acre.
Divide by 15x15 ft = 193.7 pinches.
Divide by 7.5 pinches = 25.8 pouches
Times 400 gp for an uncommon item = 10,325 gp per acre.

Edit: I agree that looking at area gives a more accurate baseline that volume, unless the water is all exactly 15ft deep. But the above also assumes that it is less than 15ft everywhere.

[Kyouhen]

Either way this is a bad idea because its a swamp because water drains into it - if you dry it out it'll just refill. This fits in that thread where a guy was asking for ideas a terrible mayor might have :smallbiggrin:

You're better off having them look to divert local streams or something. Or just...you know...kill the grung seeing as they will undoubtedly take offence at you trying to kill them all anyway.

I was planning on running it with a dry season/wet season type thing. (Does that even work for swamps?) If the players dry it out now it'll be a few months before it starts filling again, and at that point the grung will have abandoned the area and better, more time-consuming options can be pursued. As for just killing the grung, things get a little more complicated there. The mine is being set up at the border of two nations that are one step shy of open war. The grung are from the opposing nation, and will likely end up bringing in reinforcements later. Drying out the swamp makes it harder for them to set up a new permanent camp nearby.


Move Earth seems to be the answer you really really want. 4800sqft raised 20' up with every cast, taking 2 hours a cast.

Or an army of zombies/skeletons to dig a trench that redirects the water flowing into your swamp.

Dust of dryness? About as much sense as giving a bucket to my unseen servant.

Hmmm... That definitely seems like a better idea. Maybe I'll loan them a magic item for that instead, though the idea of having them try to protect a bag full of marbles is still somewhat amusing.


Some swamp druids are going to want to have a word with them.

Yeah, that's one of the points. The players will be paid well to do this job but are going to have a hell of a time travelling through that region once word gets out that they're the ones that did it, or they could refuse and not deal with those consequences. (Or they could fail and owe someone a *lot* of money for the resources lost)


A grung who doesn't submerge themselves in water for at least an hour a day suffers a level of exhaustion. So theoretically if you instantly drained the swamp all the grung would be dead in a week.

It seems a perfect way to enrage them to attack you in the meantime of course and in practice its likely it would take much longer than a week to totally drain the swamp of all water, particularly given the grung would likely realise what was going on and make sure to store some water.

Forcing the grung to store water is most of the point. The grung really don't want the mine there and can always get reinforcements from other villages. Draining the swamp means any future attack squads need to deal with the logistics of transporting enough water, and setting up a new base camp anywhere near the mine is going to be extremely difficult.


Maybe it's just my inner Druid talking, but I'm now just dreading the ecological damage that would be done here. Like, think of all the dead fish/amphibians/whatnot that require the dampness of the swamp, to say nothing of the plants and animals...

Yep! Their employer doesn't care. Going to be fun to see what the players think of this idea.


I love campaigns that involve the planned genocide of sentient beings even more than plots that just involve the genocide of non-sentient beings.

This is some dark stuff. The swamp druids, the grungs, hell, everything's gonna be coming for that party!

And what if there are bullywugs?

Oh yeah, if they go through with this job there's going to be consequences. The nation the grung are coming from has a strong link to the Feywild and is full of nature-loving creatures. If the party goes through with this and word gets out it was them they're going to be extremely unpopular out there. :P

And yes, I'm going to expect them to dry out a grung village complete with tadpole pools. Going to be fun to see if they follow through.

[Zanthy1]

I would say that from a DM perspective I would require roughly a cart or two filled with barrels of the Dust to achieve this (assuming that each cart can hold roughly 6-8 barrels). There is no science or math behind my answer, it just seems like a good amount. Now you have a plot point: Get the cart from wherever to the new mine, and protect it while drying up the swamp. Then once all is said and done, you probably have a barrel or two full of the marbles, which have to be transported to a location where they won't be damaged. Then after the swamp is drained the mining company could even expand their mine into what was previously swamp, and work on fortifications and geographical changes to prevent the water from coming back.

[Kurt Kurageous]

I would say that from a DM perspective I would require roughly a cart or two filled with barrels of the Dust to achieve this (assuming that each cart can hold roughly 6-8 barrels).

Excellent point. Maybe this is super concentrated DoD from the DoD (dust of dryness, Department of Defense). Just get the story (and the cart maybe) rolling. It's a fantasy, go with it.

[Tetrasodium]

Firstly a swamp could be anything from 'slightly damp underfoot' to 'able to row a canoe around' which may be why you're finding it hard to find numbers.

Secondly a pinch of Dust turns a cube 15ft (~4.5m) on a side into a marble. That's 95.6m3 of water. Water has a density of 997kg/m3 so that's ~95000kg. So 95,000L or 20k-25k gallons (depending on if you're using UK or US gallons). Assuming perfect absorption anyway and the chances of that depend on what the swamp you're dealing with is like.

Plus you'd have to find somewhere to store/dispose of the pellets without breaking them...

Either way this is a bad idea because its a swamp because water drains into it - if you dry it out it'll just refill. This fits in that thread where a guy was asking for ideas a terrible mayor might have :smallbiggrin:

You're better off having them look to divert local streams or something. Or just...you know...kill the grung seeing as they will undoubtedly take offence at you trying to kill them all anyway.

Also a swamp like the floroda everglades is technically a river with a flow rate of around 3 feet per hour & omg is that water clear.
Of course, any amount of of ice9 would solve the OP's swamp problem (along with nearly every other problem in setting)

[JackPhoenix]

Also a swamp like the floroda everglades is technically a river with a flow rate of around 3 feet per hour & omg is that water clear.
Of course, any amount of of ice9 would solve the OP's swamp problem (along with nearly every other problem in setting)

How? By having somewhat higher density than regular ice?

[Grod_The_Giant]

How? By having somewhat higher density than regular ice?
I'm assuming they're talking about the version from Cat's Cradle-- a compound that freezes any water it touches into more ice 9. Which is presumably touching still more water. Given the way water systems work, you rapidly end up with everything from tiny creeks to the oceans freezing solid.

[Kyouhen]

Excellent point. Maybe this is super concentrated DoD from the DoD (dust of dryness, Department of Defense). Just get the story (and the cart maybe) rolling. It's a fantasy, go with it.

Hmmm... Actually going with a highly concentrated version could work better than using the normal stuff. I'll design it to be specialized to draw water to it as well to head off any questions about if DoD can suck water out of mud and what happens if the mud goes more than 15' deep.


I would say that from a DM perspective I would require roughly a cart or two filled with barrels of the Dust to achieve this (assuming that each cart can hold roughly 6-8 barrels). There is no science or math behind my answer, it just seems like a good amount. Now you have a plot point: Get the cart from wherever to the new mine, and protect it while drying up the swamp. Then once all is said and done, you probably have a barrel or two full of the marbles, which have to be transported to a location where they won't be damaged. Then after the swamp is drained the mining company could even expand their mine into what was previously swamp, and work on fortifications and geographical changes to prevent the water from coming back.

The "transport the dust to the camp" part is already covered. It's the reason why the camp needs adventurers to clear the grung in the first place. (Draining the swamp is going to be expensive. You can find your own soldiers to get rid of the frogs) I'd prefer using DoD over any sort of Move Earth spell though specifically for the chance of failure. Wouldn't do to have all those marbles stolen and the water put back, that dust was /very/ expensive. Leaves the players with some high risk if they fail, but if they succeed it gives them a chance at even better work.

[Tetrasodium]

I'm assuming they're talking about the version from Cat's Cradle-- a compound that freezes any water it touches into more ice 9. Which is presumably touching still more water. Given the way water systems work, you rapidly end up with everything from tiny creeks to the oceans freezing solid.

correct, I was being silly :D