The Unique Ecosystem of Las Vegas Wash Wetlands

Just a few miles off the Las Vegas Strip, lies an oasis in the middle of the desert, where the sound of slot machines and traffic is replaced by the sound of rushing water and birds; welcome to the Clark County Wetlands Park. 

Located on the east side of the Las Vegas Valley, the park extends along the Las Vegas Wash from the wastewater treatment plants to Lake Las Vegas (Las Vegas Bay).

Las Vegas Wash wetlands. (photo courtesy of Las Vegas Wash Coordination Committee)

Wetlands around the Wash are more than just a pretty oasis. The wetlands play an important role in filtering urban runoff and reclaimed wastewater of fertilizers, oil and chemicals, before it is discharged into Lake Mead. More importantly, the Las Vegas Wash wetlands create a unique habitat, hosting about 700 species of birds, mammals, reptiles and fish. 

The wetlands also function as a flood dam, controlling the erosion of the Wash. Like a big sponge, they absorb extra water from floods and gradually release them back into the river. Wetlands decrease erosion by binding the soil together. They also work as natural levees for banks by absorbing the impacts of fast moving water.

A variety of fish, which are both native and introduced species, inhabit the  Las Vegas Wash. A total of seven species including green sunfish, mosquitofish, common carp, black bullhead, red shiner, fathead minnow, and the suckermouth catfish were observed in the 2002-2003 fish surveys. However, none of the above mentioned species are native to Nevada. Non-fish species that were found during the surveys include the red swamp crayfish, spiny softshell turtle, bull frog and red eared slider. More than 200 species of birds have been found at the Wash among them are the Yuma clapper rail and Southwestern willow flycatcher. Some of the other species of animals that can be found in the Wash include the sidewinder, desert iguana, green sunfish, desert pocket mouse, hoary bat, Yuma myotis and Woodhouse's toad

Decline of wetlands

The wetlands started growing in size in the 1950s, when the first wastewater treatment facilities were opened and the Las Vegas Wash became a perennial stream. Until the 1980s, the growth of the city stimulated the expansion of the wetlands by introducing more reclaimed water into the channel. However, the increase of water flow, caused by the rapid urban growth in the 1980s, led to dramatic physical changes in the Wash. Erosion cut the channel deeper and wider, which caused the size of the wetlands to dwindle from 2,000 acres in the 1970s to less than 200 acres in the 1990s.

Erosion at the Las Vegas Wash. (Photo courtesy of Las Vegas Wash Coordination Committee)

Invasive species

Another issue that threatens the wellbeing of the Wash habitat is the expansion of invasive species such as Tamarisk (Salt Cedar) in the watershed. Tamarisks are resistant plants that take over the precious wetlands by displacing rival species. Non-native species spread quickly and alter the form and function of the wildlife habitat and nesting sites. These species are drinking up water supplies that are needed by the human and wildlife populations throughout the southwest. For example, a mature tamarisk can consume up to 200 gallons of water per day.

The wetlands also are subject to illegal uses such as hunting, dumping trash and uncontrolled vehicle operation.

 

Endangered species

Almost a dozen species in the Las Vegas wetlands are listed as endangered including the  Southwestern Willow Flycatcher, Razorback Sucker, Yuma Clapper Rail and Desert tortoise.

  

Southwestern Willow Flycatcher, Razorback Sucker, Yuma Clapper Rail and Desert tortoise are listed as endangered. (photo courtesy of Las Vegas Sun and LVWCC)

The loss of habitat, water pollution (mostly from agricultural runoff) and the invasion of non-native species threaten the existence of these animals.  The lateral erosion of the channel coupled with the construction of erosion control and bank stabilization structures have caused the habitat of these endangered species to be destroyed; however, once these structures are completed they will lead to long-term improvements of the wetlands.   

Changes in the chemistry and consistency of the flow components in the Wash (reclaimed water, urban runoff, shallow groundwater and stormwater) can acutely affect the fish and wildlife inhabitants. The fish in the Las Vegas Bay may appear healthy, but it is what is on inside that matters. Some fish in the bay and the Las Vegas Wash have mutated reproductive systems and different hormone levels than fish in other parts of the lake.

The treated water is altering the reproduction systems of fish in Lake Mead. (photo courtesy of Las Vegas Sun)

Restoration and management plans

The Las Vegas Wash Coordination Committee was formed in 1998 with the purpose of protecting and enhancing the Wash and the surrounding wetlands. The committee has contributed to the improvement of the wetlands and stabilization of the Wash’s banks through construction of erosion-control structures, planting trees and shrubs, management of invasive species and extensive wildlife, and water quality programs.

The sides of the Wash are being stabilized by planting native plants and installing flow-control structures such as dams and weirs. Weirs (low-height dams) along the Wash are permanent grade-control structures, designed to resist large storm events. They help reduce channel erosion by slowing down the flow of the water and providing a stable bed to grow vegetation. Weirs also improve the quality of the water by creating ponds that slow down the flow of water and catch excess sediment. Since the late 1990s, 13 flow-control weirs have been constructed in the Wash and three more are planned to be completed by the end of 2012.


There are controversial opinions about the impact of weirs on wetlands and wildlife habitat along the wash. Some believe that the construction of weirs can affect the fish inhabitants by impeding their upstream migration and by altering their habitat. However, it is apparent that wetlands improvement (as a result of weir construction) and vegetation enhancement activities contribute to a suitable habitat for fish and riparian species. The Las Vegas Wash Coordination Committee reports indicate the effectiveness of erosion control programs along the wash on the population of razorback sucker’s in Lake Mead. In fact, weirs have been affecting the spawning success of fish by providing a suitable environment (wetlands) and improving water quality.

Rainbow Gardens Weir, a grade control structure at the Las Vegas Wash

It is rarely expected to find an oasis of water, wildlife and vegetation in a desert valley, similar to the unique ecosystem of Las Vegas Wash. The Wash is home to many species of plants and wildlife that are not found anywhere else. The Las Vegas Wash ecosystem is also exceptional because it originated as a result of urban growth and human activities. The expansion of wetlands in the last fifty years is a measure of urban growth in Las Vegas, but at some point excessive urban growth has accompanied erosion, water pollution and wetlands degradation. Fortunately, the city is aware of the roles of wetlands in improving the environment and nesting wildlife and strives to save and enhance this precious ecosystem. Restoration and management plans, which were started in the 1990s, have brought a successful outcome and continue to restore the “urban river” ecosystem.

The Green Shadow on The Lake

Lake Mead has exhibited several algal blooms during the past decade. The most widespread bloom in 2001 has been considered very unusual for the area. "The bloom was so extensive that it spread throughout the lower Colorado River system … and even into reservoirs in the Southland region as far south as San Diego, a distance of about 400 miles," said Mic Stewart, the water quality manager for the Metropolitan Water District of Southern California.

The large algae bloom at Lake Mead in 2001 (photo left). The photo at right depicts the lake with its normal water color. photo courtesy of H2O University. (http://www.h2ouniversity.org/html/library_water_facts_algae.html

 Although authorities said the sheen of green algae on Lake Mead was non-toxic and it didn’t impact the water quality and aquatic habitat, it had a great effect on recreational business of the area with a six percent drop in the number of tourists between May and July.

The causes of the 2001 algae bloom were not completely understood; but the appearance of those blooms indicates the vulnerability of the Lake’s environment to nutrient loads (phosphorus and nitrogen). Phosphorus in the lake is provided by discharged treated wastewater, urban runoff, and wildlife; however, there is no reliable information on the magnitude of nutrients from different resources. The three treatment plants - Las Vegas, Clark County and Henderson - that dump treated wastewater into Lake Mead through Las Vegas Wash (a natural wash which drains most of the Las Vegas Valley’s excess water into Lake Mead), voluntarily remove more than 90% of phosphorus from all discharge in advance, but there is less control on the sediment load and bacterial count carried by urban runoff and stormwater.    

Causes of the bloom

It is impossible to pinpoint what exactly caused the algae bloom in Lake Mead, but it can be said that a combination of physical, chemical and biological changes over decades have influenced this event. However, most of the experts have consensus on the limiting impact of nutrient input from dumping wastewater and, most importantly, urban runoff into Lake Mead. Located in the middle of the desert, unlike Los Angeles and San Francisco, Las Vegas does not have access to the Pacific Ocean for wastewater disposal. The excess water has no other option than to return to Lake Mead. 

Urban Runoff

Excess water from lawns, washing cars and hosing down driveways washes away fertilizers (rich in phosphorus), pet waste and household chemicals, draining them directly to Lake Mead. Although urban runoff makes up for a very small portion of the Wash flow into Lake Mead, it is a concern since it carries various pollutants and nutrients from fertilizers and from the urban environment. The polluted water then is sent directly to Las Vegas Wash, without being treated. Other sources of pollution and nutrients include livestock waste and faulty septic tanks.

Excess water from lawns is drained directly to Lake Mead, without being treated. photo courtesy of Las Vegas Wash Coordination Committee

Sprawl is considered one of the main causes that raise the amount of pollutants in Lake Mead. The population in the Las Vegas Valley has been growing fast since the 1930s when the construction of the Hoover Dam kicked off the first population boom in Las Vegas. Each new subdivision in Southern Nevada results in more wastewater and runoff drains into Lake Mead.

Las Vegas Wash

Urban runoff and treated wastewater is discharged into the lake through Las Vegas Wash. The Wash is a 12-mile “urban” river that flows between the city of Las Vegas and Lake Mead. Once known as an intermittent flow, the Wash became a perennial stream as a result of the discharge of treated flows from the Valley’s wastewater facilities, which began in the 1950s. This river owes its flow to the urban population living in Southern Nevada. The Wash carries more than 150 million gallons of water to Lake Mead on a daily basis, which accounts for two percent of all the flows into the Lake. This river is the Valley’s sole drainage to Lake Mead and is comprised of four major flows: urban runoff, shallow ground water, reclaimed water and stormwater. Urban runoff and shallow groundwater seepage build the base flow; treated wastewater is added later along the lower Wash and considered the dominant flow therein. It’s not surprising that the Wash’s flow (the amount of water that is discharged into the river) has been proportionally increased with Southern Nevada’s population growth. The Wash plays an important role in extending the limited water supply for Southern Nevada residents by returning about 50 billion gallons of water a year to Lake Mead. The Wash also serves an important role as a wildlife habitat and a recreational area, featuring trails and wildlife viewing sites for the residents.

The map of Las Vegas Wash, photo courtesy of Las Vegas Wash Coordination Committee

Erosion and wetlands deterioration

Unfortunately, the increased erosion since the 80s has washed away a big portion of wetlands and has diminished their size from 2000 acres to 200 acres, reducing their performance as water filters. Wetlands along the Wash have been acting as kidneys, filtering water from oil and residues and absorbing excessive nutrients. These oases also host more than 700 species of birds, reptiles and other animals, making the Wash one of the most unique natural resources of Southern Nevada. Erosion is considered the biggest threat to the existence of Las Vegas Wash and one of the factors that stimulates algal growth.   

 

Adverse consequences

Algal blooms are considered threats to aquatic environments. Green algae are not toxic by its nature; the problem appears when they die and start decaying. “As they die, they consume oxygen and if the oxygen levels drop below a certain level, it could be bad for fish” said Tom Porta, chief of State Bureau of Water Quality Planning. Fish require at least five milligrams of oxygen per liter of water. Scientists fear the green algae are replaced by potentially toxic blue-green algae, which are toxic and harmful to fish. Plus, decaying algae provides a suitable environment for pathogen growth by increasing their hosts.

Algal blooms have adverse impacts on recreational businesses around the lake. Clear water is more pleasing for swimming and other recreational activities. Also, the value of lakefront properties is, to a great extent, determined by the clarity of the water. A turbid, smelly lake can cause a drop in real state value.

     

Also, over 17 million users from the downstream states rely on the Colorado River outflow from Lake Mead as a water resource. Any water quality issues in the Lake affect not only the Las Vegas users but all the downstream consumers as well.

Since 1998 many water coalitions have tried to tackle the water quality issue in Lake Mead. The SNWA has spent millions of dollar to modify the water quality by upgrading wastewater treatment plant, promoting water conservation and water recycling and conducting numerous studies.  (Many of the SNWA’s conservation programs such as the turfgrass replacement plan could contribute to less chemicals and fertilizer in runoff.)   

In spite of all the conducted measures to decrease nutrients and chemical loads in Lake Mead, still part of the lake display recurring algal blooms. The constant water quality issue can raise an important question: Is it worth it to increase the water supply by two percent (by draining the city’s runoff, and effluent water into Lake Mead), with the expense of raising water quality issues for millions of people and degrading the valuable ecosystem?

"90 by 20", A New Benchmark in Residential Water Consumption

Photo courtesy of 90 by 20

As drought has worsened during the last decade, communities around the Colorado River basin who rely on the Colorado River for their water are urged to do their part in water conservation. The 90 by 20 campaign has been launched by a group of advocacy organizations to direct urban communities’ water usage in better, smarter ways.This campaign is asking communities from Colorado to Utah, Nevada and Arizona to take the “90 by 20” pledge and try to achieve the residential water usage rate of 90 gallons per capita per day (GPCD) by 2020. 

The Colorado River’s long term sustainability is threatened by climate change and an increasing water demand. According to the US Bureau of Reclamation, the temperature rise in the 21^st century could adversely affect the Colorado River’s flow by 9 percent decrease over the next 50 years. The river, which stretched from the Rocky Mountains to the Seaof Cortez in Mexico until 1998, now ends in the Sonoran Desert, miles away from its previous destination. From 1971 to 2008, municipal and industrial consumptions in the river basin increased by 23 percent due to the population growth and economic activities.  “The region now takes more water from the basin than what Mother Nature supplies.” Evidence shows the status quo of the Colorado River basin by all means is not sustainable.

Mountain snowpack in the western US in two consecutive years. (photo courtesy of the 90 by 20)

“The challenge of increasing demand and decreasing supply is a Basin-wide problem that demands Basin-wide solutions,” says Drew Beckwith, the water policy manager for Western Resource Advocate, a nonprofit environmental law and policy organization that supports the campaign.

Historical 10-year running average Colorado River Basin supply and use (photo courtesy of  90 by 20) http://90by20.org/report.pdf

The campaign is focused on the cities located in the Colorado basin. Almost 36 million people from Colorado, Utah, Nevada, Arizona, California and Mexico rely on the Colorado River as their water resource.  The Colorado River basin would save at least one million acre-feet of water if each household in the region used an average of 90 GPCD or less. This is enough water to supply agriculture in Arizona or to provide water needs for three years in Colorado or for two years in Las Vegas.

One important key to achieving the goal of 90 GPDC is a sound partnership with policy leaders and water conservation groups in each region like the Southern Nevada Water Authority (SNWA). The campaign efforts to engage individual residents through communities and social media and encourages them to find better ways for saving water and putting the region on a sustainable path.  

According to the 90 by 20 reports, 90 GPDC is a realistic goal for residential units. There is no single set of instructions for all the communities, but the campaign offers the communities to build up their own path to 90 GPDC according to their needs and preferences. Among the communities in the basin, many are close to the goal while others need more effort to reach it e.g. Aurora and Castle Rock in Colorado are already at 90 GPCD, but people in Las Vegas need to cut off about 35GPCD to show their commitment.

Residential GPCD in the Colorado River Basin by water providers. (photo courtesy of 90 by 20)

While the program’s supporters are confident that Southern Nevada residents will reach the goal, some question if the campaign is asking too much of the residents. They argue that the 90 by 20 massage conflicts with the SNWA’s goal of 125 GPCD (for outdoor and indoor residential water usage) given that Southern Nevada doesn’t rely solely on the Colorado River for water and that it recycles 40 percent of the water it uses back into the river.

“It’s a conservation theme, but it’s like two choirs singing different songs. It can clash as far as messaging,” Doug Bennett, SNWA Conservation Manager says. “We think it’s unreasonable for people in different communities to be expected to perform at the same level.”  Some others argue about the California’s allotted water from the Colorado River and think that if California, like other upstream states, participated in conservation programs, there would be more water left for the upstream states.  

Given all these, the program’s main goal for the Southern Nevada residents is to have the phrase “90 by 20” in the back of their minds whenever they use water. The program is in its infancy stage and needs support from the residents and groups such as SNWA to succeed. “Everybody agrees water is the foundation to any community,” Dempsey, the southern Nevada coordinator for the 90 by 20 water conservation campaign says. “You can’t have growth, infrastructure, dining and quality of life without water.”

Rebates that "Make Cents"

The pioneers who established the cities in the west, as Pat Mulroy mentions, tried to recreate the east-coast landscape of lush turf grass, but this type of landscaping is not working anymore. Southern Nevada is facing a drought and the current water resources cannot meet the lavish lifestyle of the residents; it is time to change the wasteful habits. Despite the common belief, casino-hotels are not the real water-waster in the city, but outdoor sprinklers that water lawns and golf courses beyond the Strip account for 70% of southern Nevada’s water use.

Since the SNWA warned the business-owners and residents about the water shortage and upcoming drought in the mid-90s, officials have been struggling to find ways to get people to conserve this rapidly declining resource. The hotel-casino owners were first to adopt water conservation programs; many of them have cut off their outdoor irrigation water by converting to smart-landscaping as  part of their conservation plan.

NYTimes.com - Las Vegas' Changing landscape. http://www.youtube.com/watch?v=Sv1zd23f-E0

Water-smart (xeriscape) landscape rebate program

The SNWA adopted the Water Smart Landscape Rebate Program in 2000. This program was the result of a 5-year study of water use reduction through converting turf-grass to drought-tolerant landscaping and plants local to the region. 

Through this program, SNWA pays the residents $1.5 for every square foot of lawn they remove and replace with drought-tolerant landscaping up to the first 5,000 square feet converted per property per year. Beyond the 5,000 square feet, the rebate decreases to $1 per square foot. The maximum award for any property in a fiscal year is $300,000 and certain restrictions apply to well-owners. As a condition of this program, people have to sustain their new water-smart landscape for at least 10 years. The only way to convert the landscape back to turf is through a change of ownership after 10 years. Data shows the new owners usually keep the landscape the way it is and rarely convert back to turf-grass.

The concept of xeriscaping was first introduced by the Denver Water Department in 1978.  Xeriscaping is a method of landscaping which helps reduce the supplemental irrigation water through the use of drought tolerant and plants local to the area.This method is now very popular in many Western and Southern cities, such as Las Vegas, Austin, Albuquerque and Atlanta. (Photo courtesy of TreeHugger) http://www.treehugger.com/corporate-responsibility/5-great-green-ways-us-cities-are-leading-by-example.html

Along with the xeriscape rebate program, the SNWA has adopted other water restrictions to limit further water waste including a mandatory watering schedule for residents and turf limits for different building sectors and new properties. Violation of these restrictions will result in a waste-water fee or termination of water service.

The watering schedule allows people to water their lawn once a week in the winter, every other day in the spring and fall and every day in the summer. Most residents comply with these restrictions. Kim Bavington who has a small, lush piece of grass in the front yard soon has to cut back watering her lawn because of the new restrictions. She says, "I think if you take your sprinkler and time each section, so it's more efficient you can still have a great looking yard."

Other restrictions in force include fountains& water features, golf course water budgets, government facilities, mist systems, parks and community use areas, pools, surface,equipment and building washing and vehicle washing.

Studies show landscape conversion has provided a good opportunity for water conservation in the Las Vegas Valley. According to a study by SNWA, while the residents have applied an annual average of 73gallons/sq ft of water to turf grass, only 17.2 gallons/sq ft is needed for xeric landscape areas which means a 74% decrease in irrigation water. Since the implementation of the rebate program in 2000, over 155 million square feet of turf have been converted to water-smart landscaping, saving the city more than 1.5 billion gallons of water each year.

Water Savings Summary from Water Smart Landscapes Rebate Program. (photo courtesy of Western Resource Advocates)

A study by Western Resource Advocates shows that the water saved by the Water Smart Rebate Program will make up for the conversion rebate cost in a 10-year life span of the landscape. According to SNWA, water-smart landscapes are rarely converted after the conditional 10 year period and the change of ownership. Conversion rebates cost SNWA an average of $575per acre-foot of water saved; however, the study has estimated that SNWA Water Smart Landscape Program is cost-effective because SNWA would net $35.8 million for every 10-million square feet of turf grass converted to drought-tolerant landscaping.