What happens to local weather/climate when cities tear out lawns?

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Climatic consequences of adopting drought tolerant vegetation over Los Angeles as a response to California drought, Vahmani and Ban-Weiss, GRL, July 2016 found that when you tear out lawns, it gets warmer during the day but that overnight cooling could more than balance things out:

Transforming lawns to drought tolerant vegetation resulted in daytime warming of up to 1.9?° C, largely due to decreases in irrigation that shifted surface energy partitioning toward higher sensible and lower latent heat flux. During nighttime, however, adopting drought tolerant vegetation caused mean cooling of about 3?° C, due to changes in soil thermodynamic properties and heat exchange dynamics between the surface and ground. Our results show that nocturnal cooling effects, which are larger in magnitude and of great importance for public health during heat events, could counterbalance the daytime warming attributed to the studied water conservation strategy.

This being L.A., sea breezes are of course important too, which means that of course it’s complicated and hard to generalize. h/t Kevin Anchuaitis.

In which Sandra Postel has some nice things to say about my book

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I wanna tell you the story of the time I met Sandra Postel in a dry riverbed in the deserts of Mexico.

When I first started writing about water more than two decades ago, the work of the water scholar Postel was both informative and inspirational. As much as anything I came across, her work convinced me that dealing with water scarcity was a problem that mattered, that was worth’s a life’s attention. Which is why this, on the back cover of my book, means so much:

Sandra Postel on "Water is For Fighting Over"

Sandra Postel on “Water is For Fighting Over”

In the many years since, I came to write a lot about water, and Sandra moved to New Mexico, we’d traded emails, but we’d never actually met in person until one warm day in the spring of 2014, in a dry sandy riverbed on the Sonora-Baja border in northern Mexico.

A crowd was gathering, as the people of San Luis waited for the water to arrive, the environmental “pulse flow”. A woman walked up to me, mistaking me for someone else, extending her hand in greeting: “Karl, nice to meet you, I’m Sandra Postel.”

“I’m not Karl,” I responded (it turned out we both were looking for the same Karl), “I’m John Fleck.” And for the next few hours, we shared the joy of the community of San Luis and the larger community of the Río Colorado as the water arrived in the normally dry riverbed. For all of us who were there, it was magical. As a journalist I live for the wonkish details of water measurement and legal minutiae, and then there are moments that will carry you away down the story. Such was the magic of the water flowing past San Luis. That day forms the rhetorical spine of my book, there at the beginning and there at the end.

So it’s a great joy to have Sandra’s kind words on the jacket.

Water is For Fighting Over and Other Myths About Water in the West officially goes on sale Sept. 1, but I keep hearing from friends and colleagues who’ve pre-ordered from Amazon or Island Press and say copies are beginning to trickle out.

New Mexico’s long history of not building dams on the Gila

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Laura Paskus writes:

Almost 50 years ago, on June 14, 1967, four couples fired off a telegram from Las Cruces to Sen. Henry Jackson, a Democrat from Washington. Called “Scoop” by his pals, Jackson chaired the Senate committee looking at a bill to authorize the Central Arizona Project, a system of dams, canals and aqueducts on the Colorado River and its tributaries.

The bill would grant New Mexico some new water rights and also call for Hooker Dam. Planned for the Gila River, its reservoir would back into the nation’s first wilderness area, designated in 1924.

In the telegram, the couples registered their opposition to the dam. They complained that a lack of information was discouraging public participation. Building Hooker, they wrote, would violate the Wilderness Act.

We’re at it again, with a fresh discussion of a diversion that would take water from the Gila River in southwest New Mexico. Hooker and a persistent list of similar proposals, as Paskus explains, have foundered on the problem of high cost for little water. Critics expect the same thing to happen this time around, but the lure of water for human needs in a dry place like southwest New Mexico is strong.

Driest monsoon start in Albuquerque since 1993 and a drying Rio Grande

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With just a quarter of an inch of rain (0.63 cm) since July 1, this is the driest start to a monsoon season in Albuquerque since 1993, (source) and it’s been hot – 3 degrees F above average, according to the National Weather Service.

The result, Laura Paskus reports, is a drying Rio Grande:

The river began drying in mid-July as managers allow water to flow into irrigation channels. Currently, there are about 17 miles dry south of Albuquerque, between San Antonio and the southern boundary of Bosque del Apache National Wildlife Refuge.

July has been tough on everyone, says David Gensler, hydrologist with the Middle Rio Grande Conservancy District, which delivers irrigation water to farmers between Cochiti and Elephant Butte. “After a pretty easy spring, the high temps have done a number on us,” he says. “Every farmer from Cochiti to Socorro needs water, and needs it yesterday.”

Colorado River Lower Basin water users leaving nearly 500,000 acre feet in Lake Mead this year

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I’m happy (nay enthusiastic!) to point out the way Lake Mead keeps dropping, but it’s worth nothing this as well: Colorado River water use in Arizona, Nevada, and California this year is currently forecast at 7.006 million acre feet (source: pdf), well below the three states’ nominal legal entitlement of 7.5 million acre feet.

The current forecast:

  • Arizona: 92 percent of its 2.8 maf entitlement
  • California: 95 percent of its 4.4 maf entitlement
  • Nevada: 84 percent of its 300,000 acre foot entitlement

This is important. The problem we face in the Colorado River Basin is that there’s less actual wet water in the system than there is legal entitlement to water. As long as people keep taking their full legal entitlement, the system keeps pushing toward a crash. These numbers reflect a conscious effort by Lower Basin water users and system managers to grapple with that reality.

In combination with a release of extra water this year from Lake Powell, upstream, the Lower Basin demand management underway now is enough to hold Lake Mead to a forecast drop of 1.6 feet in 2016 (source: pdf). That’s still a drop, but nothing like the 7 to 14 foot annual drop we’ve seen in the last few years. Not enough, but headed in the right direction.

Shoshone hydro plant, the most fascinating water right in the West

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Shoshone power plant, Glenwood Canyon, Colorado River

Shoshone power plant, Glenwood Canyon, Colorado River

On what is apparently Colorado River Day (who decides such things?) I made a little pilgrimage this afternoon to see the Shoshone hydro plant, just up river from the little town of Glenwood Springs on Colorado’s west slope.

Shoshone has a unique place in the water management of the Colorado River Basin because of western water law’s “doctrine of prior appropriation”, which says that the earliest water users have first dibs on the water in times of scarcity.

Because Shoshone was built in the first decade of the 20th century, its water right predates much upstream water use, including transmountain diversions that take water from the west slope and ship it across the continental divide for use in Colorado’s populous front range communities of the Denver corridor.

As water gets low in the summer months, those upstream users have to shut down their diversions to ensure that there is enough water in the Colorado River for Shoshone to keep generating power. But here’s the cool thing, which makes Shoshone so interesting – it’s not a consumptive water right. Shoshone “uses” the water to generate electricity, then passes it along downstream. It’s not used up.

Which means that recreational and environmental values downstream of the plant are actually enhanced by Shoshone’s “use” of water, keeping more water in the Colorado River. From an analysis by Joe Reiter, Lauren Ris, and Doug Kenney:

One of the major beneficiaries of this arrangement is the environment.  The Colorado River is home to four endangered fish species: Humpback Chub, Pikeminnow, Razorback Sucker, and Bonytail…. The Shoshone water right helps meet the flow targets needed to maintain native fish habitat set by the Upper Colorado River Endangered Fish Recovery Program, a coalition of federal, state and private organizations within Colorado, Utah, and Wyoming. It also, inadvertently, supports a successful rafting industry in Glenwood Springs. Approximately one dozen rafting outfitters operate on the Colorado River in Glenwood Canyon accounting for 72,000 trips a year and $2 million in direct revenue. Individuals make 50,000 private trips per year on the same stretch of river.

The rafters were out in force when I stopped by this afternoon, literally putting in immediately downstream from the Shoshone outfall:

rafters at Shoshone

rafters at Shoshone

Happy Colorado River Day.

All hydrology is local, Glenwood Springs edition

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Confluence of Colorado and Roaring Fork, Glenwood Springs

Confluence of Colorado and Roaring Fork, Glenwood Springs

Eric Kuhn, General Manager of the Colorado River District, took me for a walk along his river yesterday evening, pointing out the muddy flow of the Colorado, coming in from the left, at its confluence with the Roaring Fork River – the clear water coming in under the railroad bridge.

This is on the state of Colorado’s west slope, near the headwaters of the Colorado River in the Rocky Mountains. The muddy look is from rains they’ve had in recent days in the Eagle River watershed. Eric said they can tell where the storms have been by the color of the runoff.

“I flood.” UNM’s Basia Irland and the voice of a river

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Remarkable piece by UNM water professor emeritus Basia Irland:

I flood. That is what I — and all my cousins — do from time to time. It is part of our rhythm. In their hubris, humans build cities and towns right on our banks, then get upset with us when our waters rise and destroy some of their property. They try to control us by building dams and straightening our courses so that we no longer flow naturally, aiding the hydrologic cycle, creating meanders, spreading silt, and sustaining entire ecosystems of aquatic life, plants, and animals.

Urban water, urban birds

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Black-necked stilt, Gilbert Water Ranch

Black-necked stilt, Gilbert Water Ranch

When I’m in Phoenix, I always try to squeeze out some time to go birding at the Gilbert Water Ranch, a constructed wetland where practical water management has been turned into a lovely urban amenity.

A fascinating new project by Arizona State University graduate student Riley Burnette (pdf) attempts to quantify the role that the greater Phoenix metro area’s urban water plays as water bird habitat.

Yes, Phoenix is apparently a water bird hot spot!

Cities within the arid Southwest often act as a mesic relief to the dry surrounding habitats, offering similar resources as the natural riparian strips waterbirds have traditionally been shown to use. In desert cities, waterbirds have the potential to use the 6 large amount of aquatic resources provided by the reallocation and distribution of water. In Phoenix, the Arizona Game and Fish Department has been conducting a waterbird census since 2006 and determined that numerous urban water-bodies attract a proportionally higher diversity and abundance of waterbirds than anywhere else in Arizona.

This is often accidental, but Burnette argues that this presents management opportunities:

Urban riparian areas are often a direct interface between humans and nature, and can catalyze socioeconomic and ecological revitalization of cities…. A combination of aquatic features can provide a number of ecosystems services, including 65 increased biodiversity, and a better understanding of the system will allow for managers to direct decisions for desired outcomes.

One of the implications here is that water conservation, often an unquestioned goal (by me!), has implications for urban ecosystems:

It is interesting to consider some of the potential outcomes if the “leakiness” of stormdrains are improved or the amount of public water is reduced…. As water conservation becomes increasingly important…, there must be awareness that water is a multi-faceted resource with the potential to optimize habitat and support biodiversity in addition to providing public services….