I am SO glad you asked about why I don’t want a well (although you may be sorry you did!). Because I’ve been meaning to look into the details of the water situation here, and your question gave me the impetus to do that today.
The short answer is sustainability – just having heard little bits about the global water situation – I’m not an expert. Or maybe it’s not even that, it’s just a feeling I have that what falls out of the sky ought to be enough, if we’re wise, and that using more is a kind of profligacy.
Here’s some of what I read today:
Fresh water is a renewable resource, yet the world’s supply of groundwater is steadily decreasing, with depletion occurring most prominently in Asia and North America, although it is still unclear how much natural renewal balances this usage, and whether ecosystemsare threatened.” (Wikipedia, “water resources” – a lot of this info is from Wikipedia, I haven’t checked it out for accuracy, fwiw.)
Basically the picture is that we are overusing groundwater, using it faster than the aquifers can recharge. Some of our aquifers took hundreds to thousands to millions of years to form. Some do not recharge at all (it seems); some refill, but slowly. Although the techology to measure these things is improving, we just don’t know how fast the aquifers are recharging, but it’s darn sure not as fast as we are using them. The Oglalla aquifer, which underlies much of the Great Plains, is famously “drying up”:
About 27 percent of the irrigated land in the United States overlies the aquifer, which yields about 30 percent of the ground water used for irrigation in the United States. Since 1950, agricultural irrigation has reduced the saturated volume of the aquifer by an estimated 9%. Depletion is accelerating, with 2% lost between 2001 and 2009 alone. Certain aquifer zones are now empty; these areas will take over 100,000 years to replenish naturally through rainfall.
The aquifer system supplies drinking water to 82 percent of the 2.3 million people (1990 census) who live within the boundaries of the High Plains study area. (Wikipedia, Oglalla aquifer)
(This is in Saudi Arabia)
In 1980, faced with a federal ultimatum to stop overusing groundwater, the Legislature imposed new rules on five areas of the state: parts of Maricopa, Pinal, Pima and Santa Cruz counties, along with the Prescott area. In general, groundwater use is restricted in those areas, and new homes must come with a provable 100-year supply of renewable water.
The risk to the aquifers at the time was dire. The U.S. Geological Survey estimated that groundwater levels in some parts of metropolitan Phoenix had dropped 220 feet over about 40 years. As the aquifers compacted, the ground sunk, sometimes slowly, sometimes abruptly in the form of gaping sinkholes. The damage cannot be repaired. (http://tinyurl.com/n7lxgkb)
Now for some hydrology nerdiness, in case like me you’re wondering exactly what is an aquifer (skip at will):
An aquifer is a layer of porous substrate that contains and transmits groundwater. When water can flow directly between the surface and the saturated zone of an aquifer, the aquifer is unconfined. The deeper parts of unconfined aquifers are usually more saturated since gravity causes water to flow downward.
The upper level of this saturated layer of an unconfined aquifer is called the water table or phreatic surface. Below the water table, where in general all pore spaces are saturated with water, is the phreatic zone.
Substrate with low porosity that permits limited transmission of groundwater is known as an aquitard. An aquiclude is a substrate with porosity that is so low it is virtually impermeable to groundwater.
A confined aquifer is an aquifer that is overlain by a relatively impermeable layer of rock or substrate such as an aquiclude or aquitard. If a confined aquifer follows a downward grade from its recharge zone, groundwater can become pressurized as it flows. This can create artesian wells that flow freely without the need of a pump and rise to a higher elevation than the static water table at the above, unconfined, aquifer.
The characteristics of aquifers vary with the geology and structure of the substrate and topography in which they occur. In general, the more productive aquifers occur in sedimentary geologic formations. By comparison, weathered and fractured crystalline rocks yield smaller quantities of groundwater in many environments. Unconsolidated to poorly cemented alluvial materials that have accumulated as valley-filling sediments in major river valleys and geologically subsiding structural basins are included among the most productive sources of groundwater. (Wikipedia, “groundwater”)
There are three sources of freshwater:
1) Surface water is water in a river, lake or fresh water wetland. Surface water is naturally replenished by precipitation and naturally lost through discharge to the oceans, evaporation, evapotranspiration and sub-surface seepage.
2) Under river flow: Throughout the course of a river, the total volume of water transported downstream will often be a combination of the visible free water flow together with a substantial contribution flowing through sub-surface rocks and gravels that underlie the river and its floodplain called the hyporheic zone. For many rivers in large valleys, this unseen component of flow may greatly exceed the visible flow. The hyporheic zone often forms a dynamic interface between surface water and true ground-water, receiving water from the ground water when aquifers are fully charged and contributing water to ground-water when ground waters are depleted. This is especially significant in karst areas where pot-holes and underground rivers are common.
3) Sub-surface water, or groundwater, is fresh water located in the pore space of soil and rocks. It is also water that is flowing within aquifers below the water table. Sometimes it is useful to make a distinction between sub-surface water that is closely associated with surface water and deep sub-surface water in an aquifer (sometimes called “fossil water”). [I’ve read that “fossil water” refers specifically to water in a confined aquifer, meaning it’s been there a very very long time and is not able to be recharged.]
Sub-surface water can be thought of in the same terms as surface water: inputs, outputs and storage. The critical difference is that due to its slow rate of turnover, sub-surface water storage is generally much larger compared to inputs than it is for surface water. This difference makes it easy for humans to use sub-surface water unsustainably for a long time without severe consequences. Nevertheless, over the long term the average rate of seepage above a sub-surface water source is the upper bound for average consumption of water from that source.
The natural input to sub-surface water is seepage from surface water. The natural outputs from sub-surface water are springs and seepage to the oceans. (Wikipedia, “water resources”)
At Reevis we had a well, for irrigation water, that was located maybe 100 yards from the creek, and I think it was about 13 feet deep (or 30?). It seems to me it must have been picking up runoff, not much different from pumping out of the creek (which we also did sometimes). That seems reasonable to do – although we always had to balance pumping out of the creek with the impact on the downstream systems.
Back on the ranch:
There is a ginormous aquifer under me, the Coconino-De Chelly aquifer; it’s 2,000 feet thick and runs up into Utah and Colorado.It lies about 5,000 feet below the surface and is bounded by impermeable rock, making it “fossil water.” Neat to know.
But if I drilled a well, it would be coming from what is called the C-aquifer. This aquifer covers practically all of northeastern Arizona. Wells in the C-aquifer are between 37 and 2,000 feet deep; in my immediate area they are at 200 to 300 feet. The AZ Dept. of Water Resources measured wells in the C-aquifer in 1990/91 and in 2003/04 and found that most of them had declined in water level, from 1 to 15 feet, but in my area, declines were more than 30 feet. The C-aquifer is recharged by precipitation (rainfall and runoff).
Here are some of the issues arising from possible overconsumption from the C-aquifer:
Aquifers of the Little Colorado River Plateau basin contain large quantities of groundwater in storage, however, they are in a sensitive relationship with the Little Colorado River and its perennial tributaries. Lowering of hydrostatic heads by excessive groundwater withdrawals may cause some perennial reaches of the streams to dry up (Mann, 1976).
The C-aquifer is the source of water for Sterling Spring at the head of Oak Creek in the Verde River basin. … Local heavy withdrawals from the C-aquifer may also cause upward shifting of the salt water interface from the evaporites in the Supai Formation near Joseph City (Mann and Nemecek, 1983)
which could cause salinization of the aquifer.
The D- and C- regional aquifers are still in hydrostatic equilibrium (steady-state); however, local groundwater sinks or cones of depression are developing in areas of heavy pumpage (Arizona Department of Water Resources, 1991) …
one of which happens to be a coal-fired generating station about five miles away from me.
There’s another aquifer, north of here, called the N-aquifer, and water levels there are declining (as much as 72 feet, I’ve read) because of heavy pumping for the Black Mesa Coal Mine, on the reservation. It’s being considered to start pumping out of the C-aquifer.
So, it appears that in general the C-aquifer is currently in balance – the population of this region is extremely low, and there is not heavy use of the aquifer, except for the industries mentioned above – but one of those industries does affect my immediate area. Even if I felt okay about using the aquifer, it would be contrary to my vision and experiment here – which is the theory that it’s possible to grow a food forest of about an acre, plus a windbreak about 600 feet long, with harvested water, without having to use groundwater. If I …
– select the species carefully
– harvest precipitation from about 10 acres and feed it on to the one acre (which is reasonable given the terrain, I think – a natural bowl, almost)
– use earthworks to store the water in the soil (whereas now, it pretty much all just runs off the property)
– and furthermore harvest rainwater from the house roof for domestic use
… well, that’s what I’m thinking.
Besides, today I read about a couple with a place very near me who put in a well. The pump alone cost $2,000, and they were happy to have SAVED $10,000 on the drilling by shopping around. Plus it needs a dedicated solar panel.
If I had that kind of money, I would buy a tractor!