Where the Water Goes (ISBN 978-1-59463-377-5), published by Riverhead Books. You can order a copy from Amazon, Barnes and Noble, IndieBound, Books-A-Million, iBooks, and other sellers.
From Where the Water Goes:
I had decided that a useful way to think about water issues of all kinds would be to trace the course of a single river, to see where the water came from and where it went. The Colorado is an ideal subject for such a study, both because of its economic importance—it has been called “the American Nile”—and because at fourteen hundred miles it’s short enough to follow from beginning to end but long enough to cross a great deal of varied terrain. Following the Colorado also gave me an opportunity to wander around in a part of the country where I once believed I was destined to spend my adult life (living in a cabin, climbing mountains, making pemmican, eating plants I’d read about in Stalking the Wild Asparagus, and writing poems in a battered notebook).
I didn’t travel the river in a boat, the way John Wesley Powell did; I followed it on land, in a succession of rental cars. During several week-long trips, the first of which began two days after my flight over the headwaters with Jennifer Pitt and David Kunkel, I traced as much of the Colorado’s length as I could without getting wet. I drove more than three thousand miles; made many stops, detours, and redundant loops; and listened to the first three volumes of the audiobook of Game of Thrones. I also received what I now think of as a graduate-level education in the river and its many dependents, human and otherwise.
My journey along the Colorado took me to farms, government offices, campgrounds, power plants, ghost towns, fracking sites, aqueducts, reservoirs, and pumping stations, and it gave me opportunities to lose myself in some truly jaw-dropping topography. My journey ended in Mexico, in a truck belonging to someone else. In that truck, a Mexican environmentalist drove Jennifer Pitt and me across an expanse of sand to a point where the river ceased to exist. Where had the water gone? By then, I had a pretty good idea.
Below are some notes on the text and a number of photographs, almost all of them taken by me during various trips a long the river. If there's anything that needs correction or amplification, send me an email (through the Contact page) and I'll do what I can.
Chapter 1: The Headwaters
For an aerial view of the entire Colorado River, I highly recommend Peter McBride and Jonathan Waterman’s beautiful photo book The Colorado River: Flowing Through Conflict. It was published in 2010 and may be hard to find, but it’s worth looking for. Also worth looking for is a National Geographic map called Colorado River Basin: Lifeline for an Arid Land. There’s an interactive version on the National Geographic website, but you can’t spread that one out on the floor. An extremely useful source of technical information about all western water projects, including Colorado-Big Thompson and Fryingpan-Arkansas, is the website of the U. S. Bureau of Reclamation. If you are susceptible to taking freshwater for granted, you should read Drinking Water: A History, by James Salzman, published in 2012.
Here's David Kunkel—the pilot who flew Jennifer Pitt and me over the headwaters—and his Maule M-7. Note the big, bouncy wheels, for emergency landings:
Pitt arranged our trip through LightHawk, an international nonprofit organization that supplies volunteer pilots and their airplanes, at no charge, for a variety of environmental purposes. When LightHawk helps the U.S. Fish and Wildlife Service relocate black-footed ferrets, the ferrets ride in small dog crates:
Jennifer Pitt and me, about to take off from Boulder:
Pitt, leaning out the window with her camera:
We had quite a view:
Longs Peak:
David Kunkel's oxygen:
Lake Estes:
What looks like a snow-covered road running across the mountains is actually the Grand Ditch, a canal built in the eighteen-hundreds to carry water to the eastern plains from the far side of the Continental Divide. It's still in use today:
And here's what the Grand Ditch looks like on the ground:
The rain systems that don't make it past the mountains to the eastern plains:
Mostly under the same clouds:
This is Gore Canyon and the Colorado River, viewed from a road that turned out not to be much of a road. That train is carrying coal:
Another coal train:
An informational sign about Sir St. George Gore, appropriately all shot-up:
Finally, back on a real road:
Chapter 2: The Law of the River
For anyone interested in western water law, Colorado Water Law for Non-Lawyers, by P. Andrew Jones and Tom Cech, is an excellent place to start. It deals specifically with water law in Colorado, but the basic concepts apply throughout much of the West. The full text of the Colorado River Compact is available online. The interview in which Grady Gammage told his story about unsuccessfully looking up “The Law off the River” was conducted in 2007 as part of an oral history of the Central Arizona Project.
Kent Holsinger, whose firm is Holsinger Law:
Here's what mining with a sluice box looked like:
And here's Horace Greeley and his super-mysterious "neck beard":
Horace Greeley again, still with the neck beard:
Error Correction: On pages 18 and 19, I screwed up my description of the history of the Union Colony, Fort Collins, and Greeley, Colorado. Sharron Due (who is working on a related film) writes:
"You write that Union Colony was irrigated by the South Platte, and imply that Fort Collins, being up river from Union colony, is also on the South Platte. That is incorrect. The South Platte is mostly allocated in the Denver area and east/northeast of Denver. Northern Colorado, from Fort Collins through Greeley, including what was then the Union Colony, was settled only by the presence of the Cache la Poudre River, a river which begins in Rocky Mountain National Park and meets the South Platte in East Greeley by the airport. That dispute of which you speak was over Poudre River water, not South Platte. The Poudre, like the Colorado and so many rivers in the western United States is over allocated as well. It is also the only federally designated wild and scenic River in Colorado. It’s history is integral to western water law and the settlement of Northern Colorado."
I actually caught that mistake after the hardcover came out, during a trip to Fort Collins, but then forgot all about it. Watch for Sharron Due's movie, which she and her collaborators have been working on for five years. The film, she told me in an email, is mainly "about water issues in the American West with the Poudre as a backdrop." Look for it in 2019.
Some of the men who negotiated the Colorado River Compact:
Grady Gammage, Jr.:
Chapter 3: Tributaries
My wife, Ann Hodgman, and I at the top of Independence Pass in June 2011. Some of that snow is headed to Mexico:
John Cleveland Osgood and the Colorado Fuel and Iron Company are probably worth a book of their own, as is the history of Crystal Valley. The website of the Redstone Inn will get you started if you are interested in learning more. Here's the inn:
Here are the old Redstone coke ovens:
Cleveholm Manor:
Delia Malone and Mary Harris (and Malone's dog), in the valley of the Crystal River:
The Crystal River, un-dammed for now:
Crystal Valley:
Beaver lodges:
Future reservoir bottom?
Great blue heron nests, up near the top:
The field trip we ran into near the Crystal River:
Mary Harris's dashboard:
Former residents of the Crystal River valley:
Blocks of marble from the marble mine at Marble:
Chapter 4: Go West
The big pink pipes in this photo are the penstocks of the Shoshone Hydroelectric Plant:
And here's the plant itself. You actually drive over part of it on I-70, which at that point is engineered more like a double-decker bridge than a highway:
The dam that diverts the water that feeds the Shoshone penstocks:
Lawrence Wright’s New Yorker article about mining lithium in Bolivia is called “Lithium Dreams”; it appeared in the March 22, 2010, issue.
The Los Alamos Scientific Laboratory’s informational film about Project Rulison:
Walter Cronkite and Terry Drinkwater’s report on the CBS Evening News:
Here's the test site itself:
The Colorado, not far from Rulison:
Fracking sites next to the river:
More fracking:
An irrigated field:
A backyard water tank:
Battlement Mesa:
Golf club entrance:
Chapter 5: Grand Valley
As with other western water projects, the U. S. Bureau of Reclamation’s website is a good source for historical and technical information about the Grand Valley Diversion Dam and its associated infrastructure. “Managing California’s Water,” published in 2011 by the Public Policy Institute of California, is easy to find online. The difficulty of turning increases in efficiency into reductions in consumption is the subject of my book The Conundrum, which was published in 2011.
Grand Valley from above:
The interface between irrigated agriculture and desert (the snaky line between green and gray is an irrigation canal):
Grand Junction's first north-south roads were named for their distance in miles from the Utah border, and the east-west roads were named with letters of the alphabet, and many of the gaps have been filled in with fractions and decimals:
Entrance to the Webbs' vineyard:
Brooke Webb:
The Webbs' grapes:
The Webbs' headgate:
An irrigation ditch in the Webbs' vineyard:
A concrete junction box:
How wine is made:
The tasting room, the economic foundation of a Grand Valley vineyard:
Down the road:
A reservoir that's part of the ditch system that irrigates the Grand Valley:
Chapter 6: Salt, Dry Lots, and Houseboats
There are many accounts of the fight to save Echo Park. A good brief one is in John Muir and His Legacy: The American Conservation Movement, by Stephen Fox, published in 1981—a book that has much else to recommend it.
The view from Route 128:
The Fisher Towers:
And the mighty Colorado:
Arches National Monument, near Moab, Utah:
Page, Arizona:
Houseboats on Lake Powell:
Houseboat amenities:
More houseboats, in a shrinking boat basin:
My companions on my walk around the docks:
The coal-burning Salt River Project-Navajo Generating Station, the power plant that helped save Echo Park:
A closer look at the power plant:
Near Lake Powell:
A desert landscape shaped by huge volumes of rapidly moving water:
An ever-lengthening Lake Powell boar ramp:
The wet end of the same ramp:
Lake Powell's receding shoreline, formerly underwater:
Still room for lots of these, though:
Chapter 7: Lees Ferry
For a week or so, my favorite book of any kind was Lee’s Ferry: Desert River Crossing, by W. L. Rusho. (The book was published originally as Desert River Crossing: Historic Lee’s Ferry on the Colorado River, in 1975. The reprint edition I own, which I bought in a marina store at Lake Powell, was published in 2003.) The John D. Lee Family organization has a website. The best book I’ve read about the Mountain Meadows Massacre is Blood of the Prophets: Brigham Young and the Massacre at Mountain Meadows, by Will Begley, first published in 2002.
Navajo Bridge, over Marble Canyon. Those are the Vermilion Cliffs on the far side:
Marble Canyon, downstream:
Upstream:
Glen and Bessie Hyde (and you can read more about them here):
The Hydes' boat where it was found, minus the Hydes:
Error Correction (corrected in paperback): On page 80, I write that men working on the first Navajo Bridge were "the last people ever to see" the Hydes. Nick Marble—who describes himself as "Grand Canyon Enthusiast (12 trips, hiking, trail running and rafting)"—has shown me that this is incorrect. He writes in an email: "Glen and Bessie hiked up South Kaibab Trail in mid-November 1928, met with several Park Service personnel (including the superintendent), chatted with a Denver Post reporter, met with Emory Kolb (who photographed them), and so forth, before hiking back down to the river and continuing their fateful (and fatal) voyage." He recommends Sunk Without a Sound: The Tragic Colorado River Honeymoon of Glen and Bessie Hyde, by Brad Dimock, published in 2001.
John Wesley Powell & Co.:
The Colorado near its junction with the Paria:
The boat launch at Lees Ferry:
Lonely Dell Ranch:
The execution of John D. Lee:
John D. Lee in his coffin:
The gauge used by the USGA to monitor the river's volume at Lees Ferry:
Chapter 8: Boulder Canyon Project
The Grand Canyon from the North Rim (the thinking person's rim):
My mother descending to the Colorado River from the South Rim in 1948, on a cross-country car trip with a college friend of hers. My mother is in the white shirt, on the third mule from the bottom:
The guide, at the head of the line, surprised my mother at one point by pouring a hatful of cold water down her back because, he said, she looked overheated. (Later, quietly, he asked her out.) A few days before, my mother and her friend had gotten lost near Santa Fe, and, at dusk, had followed a narrow mountain road that suddenly filled with trucks going the other way. The road turned out to be an entrance to Los Alamos National Laboratory, and a guard at the gate stopped the trucks so that my mother and her friend could turn around.
My favorite books about my favorite dam are Colossus: Hoover Dam and the Making of the American Century, by Michael Hiltzik, published in 2010; Hoover Dam: An American Adventure, by Joseph E. Stevens, published in 1988; and The Story of the Hoover Dam, edited by C. H. Vivian, published in 1986. That last book consists of articles that first appeared in a series of booklets published, while the dam was under construction, by an industrial trade publication called Compressed Air Magazine. (Many big, loud tools used in building the dam ran on compressed air.) The book includes some terrific photographs and illustrations, among many other enticements. I bought my copy in the gift shop at the dam. Edmund Wilson’s New Republic article about Hoover Dam is anthologized in his book The American Earthquake, which was first published in 1958 and is still in print in a paperback edition published in 1979. It’s a terrific contemporary look at the effects of the Great Depression.
Bob Gripentog and his boat:
Late afternoon on Lake Mead:
The bathtub ring, up close:
Hoover Dam from upstream:
The helicopter we saw:
At the visitors' center:
The concrete for Hoover Dam was poured in sections:
When the dam was nearly finished but before Lake Mead began to fill:
Lake Mead when it was nearly full:
Lake Mead more recently:
Terrazzo floor of a public restroom on top of Hoover Dam:
Same kind of floor down here, in the turbine room in the power plant below the dam:
Me, entranced, in the Hoover Dam visitors' center:
Lake Mead in 2009. There was once a "No Fishing" sign at the end of the pier in the photo below. The weedy area off to the right used to be reserved for scuba divers:
Recently, I've become obsessed with scanning and organizing several hundred slides my father's father shot between about 1945 and about 1963. (They'd been sitting in a sealed box for fifty years.) Here are three shots of Lake Mead and Hoover Dam, taken in 1955, which show that the bathtub ring is not a new phenomenon:
Jennifer Pitt says: "The Mead shot is a good reminder that the bathtub ring has been seen before." And she passed along this chart showing historic elevations:
The lake in 1955 wasn't quite as low as it is today—and it didn't stay low for long—but it was low.
And here's the hotel (RIP) where my grandparents (also RIP) stayed when they were in Vegas:
Note the grass in the photo above—and the running sprinklers in the photo below, in front of the other hotel where my grandparents stayed during their trip to Vegas:
Chapter 9: Las Vegas
Details about Las Vegas’s xeriscaping rebate program, called Water Smart, can be found on the website of the Southern Nevada Water Authority. For the website of the Las Vegas Springs Preserve and Origen Museum, go here.
Approaching Las Vegas from the northeast:
The Bellagio fountains:
Water use:
One of the "straws" on Lake Mead:
Xeriscaping on the campus of the University of Nevada at Las Vegas:
Xeriscaping requires irrigation, though:
An irrigated cactus at Springs Preserve. The emitter is at right:
Error Correction (corrected in paperback): On page 112, I describe the natural climate of Los Angeles as "desert"; the correct term is "semi-arid"—or, as residents often prefer, "Mediterranean." The point I was making is unchanged, though. The vast majority of the plants that grow in L.A., including not just the citrus trees and the flowers that fill residential gardens but also every one of the city's familiar palm trees, were imported from somewhere else and wouldn't exist without irrigation. Many of the palm trees were planted in the nineteen-twenties:
There is no native or non-irrigated vegetation in this photograph of a yard in L.A.:
Chapter 10: Colorado River Aqueduct
There are several biographies of William Mulholland, including one by a granddaughter, Catherine Mulholland: William Mulholland and the Rise of Los Angeles, published by the University of California Press in 2000. Catherine Mulholland is probably overly sympathetic to and defensive about her subject, but the book is full of interesting material, including a number of cool photographs, and it’s a useful counterbalance to books that treat Mulholland as evil incarnate.
London Bridge, Lake Havasu City, Arizona:
The view from my room on Lake Havasu (not at the London Bridge Resort, I'm sorry to say):
Parker Dam:
Donald Nash and his daughter, Baily, at the Whitsett pumping plant:
Error Correction (corrected in paperback): On page 124, I muddled the history of the Los Angeles City Water Company and the Los Angeles Aqueduct. The water company was succeeded not by the Metropolitan Water District of Southern California, as I wrote, but by the Los Angeles Department of Water and Power, which built the Los Angeles Aqueduct in 1913. The MWD was created by the state legislature fifteen years later, in 1928.
Some of the big pipes that carry the water uphill, toward Los Angeles:
The General Electric pumps:
The big old transformers:
The route of the Colorado River Aqueduct, from Lake Havasu (far right) through the mountains to metropolitan L.A. (far left):
The design of the siphons:
Tools from the early days:
No swimming past this point:
Quagga mussels:
Quaggas (and Asian clams) up close:
Bald eagle nest (the dark area at lower right) after attack by golden eagles:
Copper Basin:
And its outlet, where the chlorine solution is injected:
Easy living along the river downstream from Parker Dam:
Irrigation downstream from Parker Dam:
Cotton:
Chapter 11: Central Arizona Project
Transcripts of the interviews that make up the oral history of the Central Arizona Project can be downloaded from the project’s website. Stewart Udall wrote an early book about the environment, The Quiet Crisis, published in 1963, a year after Rachel Carson’s Silent Spring. It’s till a good read.
An irrigation ditch carrying CAP water to a farm field not far from Tucson:
A headgate:
Fertilizer or herbicide being added to water as it's pumped from a ditch to a field:
Chapter 12: The Rule of Capture
Robert Glennon is also the author of another good book about water: Unquenchable: America’s Water Crisis and What To Do About It, published in 2009.
My part of the country recently suffered a multiyear stealth drought, which people tended not to notice until their well randry. In my book, I mention a friend with a dug well that produces more water than my much deeper well does—but not anymore! It dried up after this book went to press, and my friend and his wife ran a hose up to their house from a house down the hill. My well is under this overturned whiskey-barrel half:
The owners of two huge houses houses near my town's village green have installed three new wells between them, mostly to water acres of grass and planting. This one added a 10,000-gallon water-storage tank, too, under the mound toward the left of the photo (the well is at the right). The lawn you see—and much more to the left—is part of a roughly one-acre second lawn, created by clearing trees from an adjacent lot and carpeting the ground with six-foot rolls of sod, delivered by three semi-trailers:
The people who owned (and totally renovated) this gigantic house also added several thousand plants and an extensive irrigation system, fed by two wells. You can see loops of irrigation line in the foreground. You would think that native vegetation could survive on native precipitation, but maybe not:
Saudi Arabia's experiment in locavorism:
Chapter 13: Boondocking
Confinement and Ethnicity, the National Park Service’s 1999 book about internment camps, resonates today and is worth tracking down. The full text of the Quantification Settlement Agreement for the Colorado River can be found online. You can learn more about military recreational facilities here.
Just south of Parker Dam:
The Colorado River Indian Tribes own the right to use more than 700,000 acre-feet of Colorado River water—about a quarter of Arizona's entire allotment:
The Colorado River at Mayflower Park:
Hidden Beaches:
Quartzsite, Arizona:
Water for sale:
Atomic cannon:
Hidden Shores:
The tiny golf course near the entrance:
Merry Christmas:
Chapter 14: Imperial Valley:
There’s some interesting historical material about the Imperial Valley in (of all things) The Story of the Hoover Dam, that collection of Compressed Air Magazine articles I mentioned in my note on Chapter 8.
Lawrence Cox:
One of Cox's onion planting charts:
Turning off the malfunctioning section:
Lettuce:
A drainage ditch carrying excess water away from the fields:
Planting lettuce:
Lettuce planting-and-harvesting schedule:
Sprinklers running:
Sudan grass compressed and wrapped for shipment overseas, at a facility down the road from Cox's farm:
Chapter 15: The Salton Sea
I invited my wife to join me in watching Plagues & Pleasures on the Salton Sea, a documentary narrated by John Waters, and doing that was a big mistake because she found the whole thing horrifying and deeply depressing. It will give you a feel for the place, though, as will a companion video compilation called Past Pleasures at the Salton Sea. Both are available on CD from Amazon. Hazard’s Toll is easy to find online. The Redlands Institute has a cool free digital version of the Salton Sea Atlas on its website.
The Julian Hinds Pumping Station on the Colorado River Aqueduct—just visible at the foot of the Eagle Mountains, past the right edge of the tree in the foreground:
Box Canyon Road:
A sign by the road:
The Coachella canal:
Not coal this time—maybe part of the harvest from the Imperial Valley and Mexico:
Error Correction (corrected in paperback): Bob Saigh points out that, when I say on page 193 that I drove down the western shore of the Salton Sea on Highway 111, what I really mean is that I drove down the eastern shore. Maybe because I was driving "down" I felt that west must be to my left. I was happy to be able to tell my wife that I had made this mistake because she has no sense of direction whatsoever.
The accident that created the Salton Sea:
The Imperial Valley and the Salton Sea a little over a century later:
The Salton Sea in its prime:
And the Salton Sea today:
The "beach":
Real-estate deals:
One of many ruins:
The restored yacht club:
Where the Beach Boys used to tie up their boat:
Bombay Beach:
Salvation Mountain:
Salvation Mountain from behind:
Inside:
The current curator's headquarters:
Slab City:
The Range, at Slab City:
The southern end of the Salton Sea:
And a thermal electricity generating plant on the shore:
In memory of one of the Salton Sea's early protectors at the southern end of the Salton Sea:
Chapter 16: Reclamation
The website of the U. S. Bureau of Reclamation is vast and terrific. Many potential rabbit holes. A fascinating and potentially endless place to poke around.
The spillway of the Laguna Diversion Dam:
The woman I met near the dam:
The All-American Canal—bigger than the Colorado River at this point:
The abandoned RV park:
The swastika bridge:
Brock Reservoir:
The Yuma Desalting Plant:
It looks busy, but it's been idle for a couple of decades:
A trailer and RV community near Yuma:
And the old flag of the U.S. Reclamation Service:
Chapter 18: The Delta
The text of Minute 319 is easy to find online. There’s an excellent article about the pulse flow on the website of the Environmental Defense Fund, called "Bringing Back the River to the Sea." A good source of information about salt cedar is the website of the Tamarisk Coalition.
Osvel Hinojosa Huerta at Morelos Dam:
The gates that divert the Colorado River into the Mexican canal system:
The shallow seepage area behind the dam. All that remains of the Colorado River at this point is the skinny stream on the far side, between the two loaf-like clumps of green near the center of the photograph.
Mexican white gold:
Attempting to restore indigenous vegetation on the old flood plain of the Colorado:
Irrigation water for the restoration project, being pumped from a canal:
The green patch at the horizon is an established area that used to look like this:
The bridge over sand:
Border fence near the bridge:
Where's the water?
Proof that water was here at some point:
Osvel and Jennifer, with a muskrat skull at the end of the river:
Tamarisk:
The most ruined part of the former delta:
The Ciénega:
Connecting a battery to the motor of our boat:
Our guide, Juan Butron Mendez:
Pelicans near the outlet that feeds the Ciénega with salty water from Arizona:
Chapter 19: What Is To Be Done?
An excellent way to stay up-to-date on water issues in the West, and on the Colorado River in particular, is to subscribe to the blog of John Fleck, a former journalist who is now the director of the Water Resources Program at the University of New Mexico. He is also the author of Water is for Fighting Over: And Other Myths About Water in the West, which was published in 2016.
I mentioned my visit to the Tampa Bay desalination plant in a New Yorker article about Florida sinkholes, called “Notes From Underground,” published in the March 18, 2013, issue.
Jennifer Pitt and I made a second flight, with a different pilot, down the eastern edge of the Front Range and along the Arkansas River. Here's the meandering Arkansas and the strip of irrigated farmland that runs alongside it. The main irrigation ditches are at the edges:
You can clearly see the division between the agricultural area and the unirrigated terrain:
This is an irrigated field that, unlike the fields on Lawrence Cox's farm, hasn't been leveled well, so that the applied water pools in some sections and never reaches others:
Tracks made by cattle radiating from a watering station fed by a well:
A center-pivot irrigated field, in the foreground, and a couple of fallowed center-pivot fields in the distance:
Refueling in Lyman, Colorado. Our LightHawk pilot for this trip was Andy Young:
Wind farm in eastern Colorado:
Boulder's power plant and its supply of coal in 2014 (three years before the plant stopped burning coal):
Cloud Seeding (corrected in paperback): On page 240, I wrote, "Cloud-seeding seems like moving money from your right pocket to your left, since rain that falls in one place can't fall in another." A cloud-seeding expert I met during my book tour told me that he agreed with my discussion of cloud-seeding up until that sentence. He referred me, in particular, to the following paragraphs from this website:
If cloud seeding is successful in increasing the natural precipitation by a nominal amount, say 10 percent, the additional percentage of total atmospheric water that might be precipitated would still be quite small. Typically, just more than 20 percent of the total water vapor in the air condenses to form clouds as it rises over mountains. The remaining 80 percent of the moisture remains uncondensed because the temperature of the air typically does not get cold enough.
As mentioned earlier, winter storms are typically about 30 percent efficient, so only a portion of the water vapor that condenses naturally when rising over mountains (30 percent of the 20 percent that was condensed), or 6 percent of the total moisture, ends up falling out naturally as precipitation during an average winter storm. An increase in precipitation of 15 percent translates into only an additional 0.9 percent of the total atmospheric moisture available.. Therefore, about 6.9 percent of the total atmospheric water might be precipitated when seeding is conducted. Instrumentation presently used by the National Weather Service would have a difficult time detecting a change on the order of 1 percent, along with the confounding influences of natural variability. These calculations do not consider that this additional water, now on the ground instead of in the air, remains in the hydrologic cycle. For example, a portion of this water would return to the atmosphere on relatively short time frames through evapotranspiration.
There are two mechanisms that may cause downwind (also called extra-area) effects: 1) Downwind transport of ice nuclei and ice crystals from the seeding source and 2) Invigoration of clouds by release of latent heating of freezing and their subsequent propagation out of the target area. Long (2001) provides an excellent summary of previous findings. These findings show
Extra-area effects appear to increase precipitation in the area surrounding and downwind of the target location
There is no substantial evidence that a decrease in precipitation occurs downwind from the target location
Affected downwind distances vary from 80-300 km (50 – 180 miles)
Amount varies from 15-100%
Everyone's goal:
Where the Water Goes (ISBN 978-1-59463-377-5), published by Riverhead Books. You can order a copy from Amazon, Barnes and Noble, IndieBound, Books-A-Million, iBooks, and other sellers.