Monday, July 9, 2007

water, water, but not everywhere...

Our well is out of water.

Again.

The guy who originally developed the property sent a letter around to the ten households who share the well, telling us about the situation, and blaming it on the relatively recent drilling for coal-bed methane beneath us.

The situation isn’t all that new – we’ve been having intermittent water crises for the past five years or so. What’s new, though, is that his letter coincided with a water judge’s ruling that methane producers must apply for groundwater well permits.

Coal-bed methane production certainly involves pumping out a lot of water. The methane adsorbs onto the coal, and is only released after a lot of the water is gone. And the drillers hydraulically fracture the rock to increase its permeability, and then pump more water out of it. Around the edges of the basin, where the coal crops out, landowners complain about an increase in methane seeps. And the dewatered coal has caught fire and is now burning underground in at least one place.

My groundwater comes from sedimentary rocks that fill a Laramide basin. The rocks aren’t really very permeable – there are some sandy layers, but they seem to be discontinuous (at least in road cuts), they’re poorly sorted, and they seem to have a lot of clays in them. And they are surrounded by mudstones. So even though the drillers pump out a lot of water, it’s possible that our mediocre “aquifer” isn’t hydrologically connected to the coal. Geologists from the Bureau of Land Management have made that argument in the past.

On the other hand, it’s possible that we get our water from interconnected fractures. (As a structural geologist, I get all excited about that possibility.) The ability of drilled wells to produce water varies a lot over short distances, enough that local dowsers can make a decent living telling people to drill in a slightly different spot. Maybe the sandstone is discontinuous and hard to hit, and maybe the water resides mostly in cracks. When I watched our well drillers work, I couldn’t figure it out.

And if the water comes from fractures, it’s possible that the cracks connect to the coal beds, and that the methane production has sucked our well dry. (But if that were the case, I would guess that our well water would have smelled like rotten eggs, like the methane seeps do. But our well had great water. When it had water, that is.)

There are other possible reasons why our well is dry. The population in our county has been growing at an outrageous rate. (The four new houses up-gradient from us were built since our well problems began, however, and there’s just a huge ranch beyond them. Down-gradient there’s BLM land. So the population growth doesn’t seem like a good explanation for my well, though it is probably important for other wells in the county.)

And then there’s our drought. The snows haven’t been as heavy, and the late-summer monsoon rains have been weak. This winter was much worse than the national news made it seem – we didn’t get the blizzards that kept shutting down Denver, for instance. March, especially, was warmer and drier than normal. And it was worse at my elevation – we never had to plow the driveway, there was so little snow. And the rocks that supply my water don’t extend all the way into the mountains – they end at a lower elevation, below the rain/snow line for most of this winters’ storms. They say this may be the beginning of a drought as bad as the one that drove the Ancestral Puebloans (aka Anasazi) away from Chaco Canyon – that global warming is likely to give us less winter snow, and earlier thaws, and less water overall. I worry that our water problems are only beginning.

So. Blame the gas companies? I’m skeptical of the BLM’s claims that it’s impossible for the water to be connected. I mean, the coal immediately underlies my aquifer. It’s not all that deep, really (and besides, I want to believe that brittle deformation is relevant to my everyday life). But I suspect that our real culprit is the drought (plus population growth). And that, unfortunately, is a much more difficult issue. The gas production in our basin is already dropping off. Global warming and local population growth, however, don’t seem likely to stop any time soon.

4 comments:

Mark said...

How deep are the wells around there? Are the homes also served by septic tanks? I've been dealing with trying to assess ground-water availability in fractured rock (Maryland) for some years now, and was surprised when I learned how active water witches are around here.

tectonite said...

Our development's two wells are 140 and 200 feet deep. There are septic tanks, but the soil is pretty poorly drained, and the air is nearly always dry, so everyone has a cesspool/pond. And the other important piece of info here is that our area isn't irrigated, and there isn't much in the way of lawn watering. (There's an area nearby where everyone gets water from a perched aquifer in gravels on an old, dissected river terrace. A recent study concluded that most of the groundwater came from irrigation, and that the change in landuse from irrigated agriculture to housing developments with wells was decreasing the water supply.)

Chuck said...

Have you considered dgetting tanked?

Kim said...

We had a cistern put in this spring, as soon as the ground was thawed. So although the well ran out of water, our household didn't. The community has a cistern, too, and the community has been hauling water constantly since this winter. But it gets expensive, and there are more and more people in the county hauling water, and that hints at a problem in the making.