How Cities Manage Water Scarcity in a Warming World – Bloomberg


How much water flows into Southwestern U.S. cities next year will depend on the coming snowfall and the resulting snowpack accumulation. So far, it’s not looking good.

High mountain snows, the source of most of the region’s water supplies, are projected to be lower than usual this winter in the Southern Rockies. This means that come spring, forecasters expect less snowmelt to flow into the Colorado River Basin and other nearby watersheds. In addition, a warming climate is causing accumulated snow to melt earlier and faster than before, with no guarantee that water will last until next season’s thaw.

Even though localities store the melted snow in mountain reservoirs, sometimes there’s just not enough. Many cities aren’t prepared for the water scarcity that lies ahead—their infrastructure isn’t built to handle sustained droughts or withstand an increasing number of wildfires that are magnified by a lack of rainfall.

While parts of California’s Sierra Nevada mountains have seen heavy rain and snow recently, other areas in the West remain parched. Here are four cities’ strategies for managing water scarcity.

Denver, Colorado

Denver’s chief water utility collects rain and snow across a 4,000-square-mile area, capturing about 94 billion gallons in an average year—enough to fill the Denver Broncos’ football stadium almost 157 times.

Since half of Denver’s drinking water comes from tributaries of the Colorado River on the west side of the Rocky Mountains—and the river basin has experienced a megadrought for the last two decades—the city is preparing for a future of increasing scarcity by diversifying its water sources and ramping up its conservation and efficiency programs.

A Dry Basin

Percentage area of the basin in each state of drought

Source: NOAA

“The approach is similar to an investment portfolio—diversity of supply, and of different strategies for how we provide water service,” said Jim Lochhead, Denver Water’s chief executive officer.

Only 20% of the precipitation in the state of Colorado falls east of the Rocky Mountains and onto the South Platte River watershed, according to Denver Water. The remaining 80% falls on the western side of the mountains, in the Colorado River basin catchment area. As a result, Denver has had to move water from west to east to provide for the roughly 1.5 million people living in the city and some of its suburbs.

Agricultural and municipal water users on the western side of the Rockies have criticized the city’s water management plans.

But the city has also been a pioneer in water efficiency programs, Lochhead said, noting that Denver Water uses about 2% of the water in the state to support 25% of Colorado’s population. It provides rebates for residents who buy higher-efficiency toilets and sprinklers, enforces limits on summertime lawn watering, and participates in the Environmental Protection Agency’s WaterSmart program.

Hell or High Water

Denver Water Utility has to pay $12.5 million settlement to Boulder County to be able to raise Gross Dam, one of the utility’s 15 reservoirs.

  • Urban area
  • Watershed boundary
  • River


Little Thompson River

Boulder County

COLORADO HEADWATERS

WATERSHED

South Platte River

Colorado River

DENVER-AURORA

SOUTH PLATTE

WATERSHED

Gross Reservoir

Blue River

Denver Water service area

North Fork South

Platte River

South Platte River

Boulder County

COLORADO HEADWATERS

WATERSHED

South Platte River

Colorado River

Denver Water service area

Gross Reservoir

SOUTH PLATTE

WATERSHED

DENVER-AURORA

North Fork

South Platte River

South Platte River

Boulder County

SOUTH PLATTE

WATERSHED

Colorado River

COLORADO HEADWATERS

WATERSHED

DENVER-AURORA

Gross Reservoir

Denver Water

service area

North Fork

South Platte River

South Platte River

Boulder County

COLORADO HEADWATERS

WATERSHED

DENVER-AURORA

Gross Reservoir

Denver Water

service area

SOUTH PLATTE

WATERSHED

South Platte River

Sources: ESRI, USGS, U.S. Census Bureau, Denver Water

It’s also investing in increasing water storage and making infrastructure upgrades, with a capital plan for the next 10 years of about $2.6 billion. The utility operates facilities in 12 counties—20 dams, 15 surface water reservoirs, more than 20 pump stations, 3 water treatment plants, and more than 3,000 miles of distribution pipe—enough to stretch from Los Angeles to New York.

Gross Dam, guarding the Gross Reservoir, an area of 440 acres.

The Gross Dam is at the edge of the Gross Reservoir, a Denver Water-owned reservoir, has a surface area of 440 acres, and the spillway sits at 7,225 feet elevation. Photographer: Hyoung Chang/MediaNews Group/Denver Post.

The city’s biggest water project on the books, an estimated $464 million expansion of Gross Reservoir west of Boulder, is moving ahead after objections from neighboring Boulder County. The dispute was settled in November, after Denver Water agreed to mitigate greenhouse gas emissions and environmental damage expected from raising the reservoir’s dam—in addition to paying Boulder County $12.5 million.

“Denver Water’s plan to build the tallest dam in Colorado history will hurt the 40 million people in seven states and two countries who depend on the Colorado River for their water supply,” said Daniel E. Estrin, general counsel and advocacy director at Waterkeeper Alliance.

Phoenix, Arizona

Hot, dry, and in the center of a desert, Phoenix has been preparing for drought for decades.

“It’s a given in the Sonoran Desert that one or more of our water resources will be challenged by drought,” said Cynthia Campbell, water resource management adviser for the City of Phoenix. “For that reason, we have to have water resources that exceed what we need to deliver to our customers in any given year.”

But population growth creates an additional challenge—according to census data, Phoenix experienced the largest increase in population in the U.S. between 2010 and 2020. Its water utility, Phoenix Water, serves about 1.5 million customers across 540 square miles with more than 7,000 miles of pipeline.

Phoenix relies on water supplies from four primary sources. The canals of the Salt River Project bring water from the Salt and Verde watersheds, while the Central Arizona Project connects the city with the Colorado River. Groundwater and reclaimed water make up the rest, according to the city’s 2021 water resource plan.

Treading Water

The 336-mile Central Arizona Project Canal provides Phoenix with water re-directed from the Colorado River.

  • Urban area
  • Watershed boundary
  • River


Agua Fria River

SALT

WATERSHED

VERDE

WATERSHED

Hassayampa River

Verde River

Salt River

Central Arizona

Project Canal

PHOENIX-MESA

LOWER GILA-

AGUA FRIA

WATERSHED

Gila River

MIDDLE GILA

WATERSHED

Gila River

LOWER GILA-

AGUA FRIA

WATERSHED

SALT

WATERSHED

VERDE

WATERSHED

Verde River

Salt River

PHOENIX-MESA

Central Arizona

Project Canal

Gila River

Gila River

SALT

WATERSHED

Verde River

LOWER GILA-

AGUA FRIA

WATERSHED

Salt River

PHOENIX-MESA

Central Arizona

Project Canal

Gila River

Gila River

Verde River

Salt River

PHOENIX-MESA

Central Arizona

Project Canal

Gila River

Gila River

Sources: ESRI, P.L. Chaney at Auburn University, USGS

The Central Arizona Project—a 336-mile canal that diverts billions of gallons of water out of the Colorado River every year and pumps it to central and southern Arizona—will take the bulk of water cuts coming to the state in 2022 after the Bureau of Reclamation declared shortage conditions in the Colorado River Basin. This year was the first time a shortage was declared in the almost 100-year history of the Colorado River Compact, which governs water allotments to the seven states in the basin.

Aqueduct in Scottsdale, Arizona, during the summer 2021. It is fed by the Colorado River. Water flows through the pipeline, visible from the aerial view.

The Hayden-Rhodes Aqueduct, fed by the Colorado River, during an extreme drought in Scottsdale, Arizona, on July 21, 2021. Photographer: Carolyn Cole/Los Angeles Times.

Water customers pay a flat monthly amount, but their bills can soar if they use more, which has the effect of discouraging water use for residential landscaping, Frankel said.

“You discourage waste with higher rates,” Frankel said. “We need more of that to sustain this fragile water supply in a climate change era.”

In October, the first of two rate increases will kick in to pay for rehabilitating and replacing water pipes, treatment plants, pumps, reservoirs and wells to deliver the city’s drinking water.

Phoenix also is investing in new infrastructure to move water supplies to portions of its system normally served by the Colorado River. The 66-inch “Drought Pipeline,” scheduled for completion in 2023, will supply water from the Salt and Verde watersheds in the south part of the city to areas in the north affected by shortages on the Colorado.

Grand Junction, Colorado

Nestled in a high-desert valley along the Colorado River, quickly-growing Grand Junction, Colorado, population 65,000, according to the 2020 census, has long been seen as a water-rich city in a water-scarce area at the heart of the West’s extreme drought.

“But the last few years have started to show me that we’re possibly not as invulnerable—not quite as sheltered as I might have thought we were,” said Hannah Holm, director of the Water Center at Colorado Mesa University.

Grand Junction represents growing cities throughout the West that have staked the future of their water supply on what the climate was like over the last century. But climate change has made that unrealistic.

The city gets most of its water from mountain streams fed by runoff from thawing snowpack. But temperatures are rising, leaving the city’s watershed drier and more vulnerable to wildfire. Wildfires can destroy water infrastructure and ash can affect water quality and treatment costs.

Grand Junction’s water comes from nearby Grand Mesa, the world’s largest flat-topped mountain. In a pinch, the city can obtain water from neighboring suppliers—the biggest of which, the Ute Water Conservancy District, also gets its water from Grand Mesa. The third draws water directly from the Colorado River.

From Snowpack to Water

USGS measures the thickness of the snowpack on Grand Mesa and around the U.S. with automated sensors called “snotels.”


Around April, the snotel at Surface Creek has its highest Snow Water Equivalent (swe) levels.

Colorado River

Grand Mesa

Gunnison River

Grand Junction

Colorado River

Colorado River

Grand Mesa

Gunnison River

Grand Junction

Colorado River

Grand Mesa

Gunnison

River

Grand Junction

Colorado River

Colorado River

Grand Mesa

Gunnison River

Grand Junction

Colorado River


Around July, the snotel at Surface Creek measurements drop to 0, with the integrality of the snowpack melted.

Colorado River

Grand Mesa

Gunnison River

Grand Junction

Colorado River

Colorado River

Grand Mesa

Gunnison River

Grand Junction

Colorado River

Grand Mesa

Gunnison

River

Grand Junction

Colorado River

Note: Data represented is for 2015.

Sources: USGS, Landsat

The city is preparing for drought and wildfire by expanding its interconnections with its neighbors, but the bulk of the water will still come from the mesa, said Grand Junction Utilities Director Randi Kim.

“The likelihood of the entire Grand Mesa burning is fairly low,” she said. “It would likely be portions of the Grand Mesa, which might affect one watershed or the other.”

But Colorado’s recent wildfires have been enormous. The 2020 Cameron Peak Fire, the largest in the state’s history, incinerated an area larger than New York City, including the entire primary watershed for Fort Collins, Colorado.

The 2020 Pine Gulch Fire destroyed acres of land. The picture features a calcinated landscape near De Beque, Colorado.

Land destroyed by the Pine Gulch Fire near De Beque, Colorado, on Aug. 27, 2020. Photographer: Helen H. Richardson/Denver Post.

A warning for what may lay ahead for Grand Junction came last year, when the Pine Gulch Fire scorched an area nearly the size of Chicago just outside of Grand Junction. It burned in elevations lower than the city’s watershed, but other recent fires in Colorado have spread regardless of high altitudes.

In Hot Water

The 2020 Pine Gulch wildfire burned an area the size of Chicago within the Colorado River watershed.

  • Urban area
  • Watershed boundary
  • River


YAMPA WHITE

WATESRHED

COLORADO HEADWATERS

WATERSHED

LOWER GREEN

WATERSHED

2020 Pine Gulch Fire

Colorado River

UPPER COLORADO-

DOLORES

WATERSHED

GRAND JUNCTION

Little Dolores

River

GUNNISON WATERSHED

North Fork

Gunnison River

Gunnison River

Colorado River

Dolores River

Uncompahgre River

Colorado River

LOWER GREEN

WATERSHED

2020 Pine Gulch Fire

COLORADO HEADWATERS

WATERSHED

GRAND JUNCTION

UPPER COLORADO-

DOLORES

WATERSHED

GUNNISON

WATERSHED

Colorado River

Gunnison River

Uncompahgre River

Dolores River

Colorado

River

2020 Pine Gulch Fire

Colorado

River

COLORADO HEADWATERS

WATERSHED

GRAND JUNCTION

UPPER

COLORADO-

DOLORES

WATERSHED

GUNNISON

WATERSHED

Gunnison River

Dolores

River

COLORADO

HEADWATERS

WATERSHED

2020 Pine Gulch Fire

Colorado

River

GRAND JUNCTION

UPPER

COLORADO-

DOLORES

WATERSHED

GUNNISON

WATERSHED

Gunnison

River

Dolores River

Sources: ESRI, USGS, NIFC

When it comes to the ravages of extreme wildfire and drought, “we’re learning to never say never,” Holm said.

St. George, Utah

Washington County, Utah, and its seat, St. George, were in the bullseye of a 20-year megadrought that became so extreme in 2021 that Utah Governor Spencer Cox in June declared a weekend of prayer for the divine to intervene with sheets of rain.

Unanswered Prayers

Drought index data from the second week of June, four days after the governor asked residents to pray for rain.


St. George

St. George

St. George

St. George

Source: NOAA

The county represents a nexus of extreme growth and climate change-driven long-term water scarcity. With its mild climate and proximity to national parks and Las Vegas, the county is expected to have the most rapid growth in the state. By 2065, its population is expected to jump by 229% to more than 500,000 people. And, with some of the region’s lowest water rates, it’s cheap to use a lot of it.

But climate change is making the county’s main water source, the Virgin River, less predictable and less stable as it courses down from the mountains above Zion. It can’t keep up with growth and drought.

So county officials are looking for new water to tap. Their answer: a proposed 140-mile underground pipeline that would siphon water from Lake Powell, a reservoir on the Colorado River. Zach Renstrom, general manager of the Washington County Water Conservancy District, says the lake is more reliable because its watershed is large, spanning four states, and a pipeline would give the county another tool it can use to ensure drinking water.

Head Above Water

Dry St. George will get additional water through the proposed Lake Powell Pipeline.

  • Urban area
  • Watershed boundary
  • River


ESCALANTE DESERT-SEVIER LAKE WATERSHED

North Fork Virgin

River

Santa Clara

River

Virgin River

LOWER COLORADO-

LAKE MEAD

WATERSHED

East Fork Virgin

River

ST. GEORGE

COLORADO CITY

Virgin River

Projected

Lake Powell Pipeline

ESCALANTE DESERT-SEVIER LAKE WATERSHED

Santa Clara

River

North Fork Virgin

River

LOWER COLORADO-

LAKE MEAD

WATERSHED

East Fork Virgin

River

ST. GEORGE

COLORADO CITY

Projected Lake

Powell Pipeline

Virgin River

ESCALANTE DESERT-SEVIER LAKE WATERSHED

Santa Clara

River

LOWER COLORADO-

LAKE MEAD

WATERSHED

ST. GEORGE

Projected Lake

Powell Pipeline

Virgin River

ESCALANTE DESERT-

SEVIER LAKE

WATERSHED

Santa Clara

River

LOWER COLORADO-

LAKE MEAD

WATERSHED

ST. GEORGE

Projected Lake

Powell Pipeline

Virgin River

Sources: ESRI, USGS, LPP Utah

But Lake Powell’s future also is uncertain because of the drought and growing demand for Colorado River water from California and Arizona. This year, the Biden administration declared a first-ever water shortage in the Colorado River Basin.

The St. George area represents a lot of the West: “You have places that are better endowed with water than others, and what we’ve seen in the growth patterns is that development and population growth do not necessarily occur in the locations with the most reliable water supplies,” said Peter Mayer, principal at the water consultancy Water Demand Management.

The pipeline, he said, would have junior water rights on the Colorado River and would be one of the first to be curtailed as water across the river’s seven-state basin evaporates.

Historically low water levels at the Lake Powell reservoir, in Utah, during the summer of 2021. Rocks that are normally under water are visible.

Low water levels at Lake Powell in Utah, on June 24, 2021. Photographer: Justin Sullivan/Getty Images North America.

Mayer authored a June report showing how the pipeline is unnecessary because Washington County could drastically reduce its water use, store excess water from the Virgin River for use in dry years, reuse its wastewater and more effectively manage water demand.

“If the people in Washington County were to use water the same way as in Denver, Albuquerque or Los Angeles, they could grow to the size they have dreams of and rely on their local water supply,” Mayer said.

Adblock test (Why?)



Source link

Leave a Reply

Your email address will not be published. Required fields are marked *