Precious Resource: Water Issues in the Lower Rio Grande Basin

A Publication of Sabal Palm Grove Sanctuary, National Audubon Society by David Berger

October, 1995

Future Growth

Now that past water use patterns have been reviewed, it is important to address the question of future water demands. Several factors will determine future water demands: the resident and seasonal population; the number and type of housing units; landscaped area and landscaping practices; water pricing; agricultural use; employment; climate and weather conditions and; conservation activities.

It is expected that Matamoros and Reynosa will double in size in 26 and 24 years, while the populations of Cameron County and Hidalgo County will double in 36 and 30 years. These estimates, however, do not consider the impact of migration. If the net migration gains stay constant, the population of these counties and municipalities will double sooner. Estimates show that municipal demand for water will more than double during the next fifty years. Predictions for the Lower Rio Grande Valley display that municipal and industrial water needs in Texas will rise to 180,000 acre-feet by 2000 and eventually increase to 400,000 acre-feet by 2040.

While the anticipated trend for the border municipalities is growth, Valley agriculture water demand is expected to steadily decline over the next fifty years. Lower Rio Grande Valley agricultural demand will decrease from 88.4 percent of total water use to 70.41 percent. The shift in demand can be explained by changing land-use practices such as removing land from agricultural production, decreased use of crops that consume high quantities of water, and improved efficiency in distribution. Despite this drop, agriculture will remain the largest user of water into the near future. In Tamaulipas, Mexican officials estimate that water consumption by the agricultural industry will not change (Navarro, 1995).

In conclusion, natural conditions imply that the Basin will periodically confront limited water supplies. The ability of local Lower Rio Grande residents to conserve this resource is made increasingly difficult because of the expected population growth throughout the entire Rio Grande watershed. The growth will increase the competition for water resources and may result in new conflicts. The predicted change in local water use practices, such as decreased water consumption by the agriculture industry, may somewhat ease water pressures. Nonetheless, given urban growth, Basin residents must continue to improve water efficiency and increase conservation efforts. An additional step to reduce water pressures must be increased cooperation on both sides of the river. By sharing information, technologies, and planning efforts, border communities can help each other to extend water resources and reduce the potential for regional conflict.

Water for Wildlife

"Among the casualties of the expanding human use and abuse of water resources are freshwater ecosystems and the plant and animal species they sustain. Although fresh water represents only a fraction of the earth's water, it supports an exceptional number of animal species. Most are feeling the impacts of increased human intervention in natural systems." - Engelman and LeRoy, 1993

What is often left out of the community planning picture have been the legitimate needs of wildlife, particularly water. The vast clearing of the border region, along with the construction of dams and flood and irrigation canals, has taken a large toll on the basin's natural resources. This said, planning and preserving the rich natural treasures of the border need not be an "us versus them" debate. The environmental perspective recognizes the important water needs of people and industry. Yet, it also recognizes that with careful planning and increased efficiency the needs of wildlife can also be met. If Lower Basin residents want to ensure the survival of biodiversity in the region and benefit from the availability of natural areas, they must consider how development projects and water consumption impact wildlife and habitat. Secondly, border communities must take action to protect riparian habitat and provide sufficient streamflows.

The Lower Rio Grande Basin's ecology is both unique and precious.This area hosts an environment of rare and spectacular wildlife and plant species fueling an important local eco-tourism industry. Critical to the creation and survival of the region's environment and diverse habitats is water.

The Basin was historically prone to a pattern of periodic flooding and droughts that shaped this land. The Rio Grande's flooding carried rich and fertile alluvial sediments enriching the soils in the Basin and sustaining the border habitat. This habitat, in turn, attracted and supported the region's diverse wildlife. Unfortunately, the natural resources and habitats of the border have been under siege for quite some time due to agricultural and urban development. The development of the Rio Grande basin has negatively affected native wildlife and habitat resulting in the endangerment and extinction of a large number of species. While nature has shown great resilience and an ability to survive extensive clearing of habitat, even nature has limits.

Impact of water development projects

Prior to the construction of the international Amistad and Falcon reservoirs, the lower Basin was subject to periodic flooding. "Between 1900 and 1939 the Rio Grande overflowed 23 times (Ramirez, Jr. 1986.)." Historically, the river would meander and change course. This movement cut river channels throughout the landscape which would refill during floods. Today, these channels, or ox-bow lakes; are locally known as resacas.

The extensive construction of impoundment facilities, floodway systems and irrigation canals during the twentieth century caused significant changes in the hydrology and biology of the Lower Rio Grande region. One result is that the river no longer meanders or naturally fills the resacas.

Another result of water development projects, in particular dam and irrigation development, has been decreased water flow in the river. According Edwards and Contreras-Balderas, "water, once removed, does not reenter the river as 'return flow.' Instead, this water flows into floodways and irrigation systems and eventually enters on of the Laguna Madres of Texas or Mexico... or merely evaporates into the atmosphere due to the common flood irrigation practices used in this region (Edwards and Contreras-Balderas, 1991)." In addition to increased water usage and diversions, the river must bear a heavier load of contaminants from urban and agriculture effluents and these contaminants can find their way into the bodies of animal species (Edwards and Contreras-Balderas, 1991).

The decrease in streamflows and increased contamination of water have negatively impacted riverine flora and fauna and contributed to the replacement of native freshwater species with non-native or estaurine species (Ramirez, 1986). The suspension of the natural cycle of flooding has also led to the transformation of terrestrial riparian habitats. This transformation "may be responsible for the natural replacement of...riparian woodland species such as hackberry, cedar elm, and Montezuma bald cypress with xeric (dry) species such as mesquite (Ramirez, 1986)."

Loss of wildlife

Today, there are more endangered wildlife species along the border than anywhere else in the United States. Sixty-seven vertebrate species are considered endangered or threatened while several species have been lost forever. These losses result from the destruction of habitat, the poisoning of the environment, increased salinity, and the decline in the normal streamflows.

River flows are important for the development of riverine and estaurine species that use the mouth and lower reach of the Rio Grande as a nursery area. This includes the white and brown shrimp (Ramirez, 1986). "Adequate freshwater inflows are critically important during the early stages of development of postlarval and juvenile shrimp. The brackish conditions caused by the freshwater inflow exclude predatory adult finfish that prefer higher salinity. Freshwater inflows also transport nutrients and detritus necessary for the development of juvenile shrimp (Ramirez, 1986)." Several other fish species, such as the flounder, redfish, black drum and croaker also depend on freshwater inflows for reproduction and growth. Unfortunately, according to Dr. Salvador Contreras, changes in the river have resulted in the extinction of four species and several species are no longer present in the lower Rio Grande (Contreras-Balderas, 1995, Edwards and Contreras-Balderas, 1991).

One important step to protect the Basin's habitat has been the U.S. Fish and Wildlife Service project to create a Lower Rio Grande Valley wildlife corridor. This agency has been purchasing land tracts throughout the Valley. Much of the land purchased for the corridor has come with water rights (Kelly, 1992). In response to declining stream flows, and the potential cancellation of the water rights on Fish and Wildlife land because of non-use, Kelly (1992) has suggested a policy of converting the irrigation water rights to "instream flow" rights. This policy would help increase stream flows critical to the survival of border wildlife.

Clearly, there are multiple demands on the Rio Grande's water supply. Water is needed for people, agriculture, and wildlife. The reality of a limited supply, however, is challenging border communities to decide what uses are appropriate and what trade-offs need to be made. Border residents will increasingly confront tough choices as the demands for water increase. Ultimately, communities will have to decide what is most important for the region and how can the region's unique quality of life and biodiversity be preserved. This will generate self-examination and raise questions such as whether water should be used for golf courses, habitat preserves and for water consuming crops - like cotton - versus less demanding alternatives. These decisions will decide what kind of environment the Lower Rio Grande residents will have in the near future and eventually leave to future generations.

Conservation

Given the growing pressures on water supplies, communities in the Lower Rio Grande Basin must formulate effective conservation policies. As the Texas Water Development Board (TWDB) explains, water conservation consists of daily practices, techniques, and technologies that will reduce consumption of water, reduce loss or waste of water, improve efficiency in the use of water, or increase recycling and reuse of water so a water supply is made available for future use (TWDB, 1991.)

The following section illustrates various methods that can improve water distribution efficiency for agriculture and municipalities. The National Audubon Society does not support any particular conservation method, but recognizes conservation needs and practices will vary according to crops, terrain, soils, and local needs. The goal, however, is to encourage the overall practice of conservation, in a manner harmonious with the natural environment, in order to reduce water use.

Conservation measures have been used successfully throughout Texas and other regions to reduce water use for overall conservation goals as well as during emergency drought conditions. In some cases, according to Texas figures, water use has been reduced by 25 percent or more under emergency conditions (TWDB, November 1991). There is absolutely no reason why conservation efforts could not be expanded or improved upon in the Basin since conservation benefits both municipalities and agriculture (See Box 3). This next section addresses some of the political and practical aspects of conserving water.

Benefits of Water Conservation

Lowering capital and operating costs for water and wastewater systems;
Postponing the need for new or expanded water or wastewater systems;
Reducing demand on limited water supplies, thereby making them available for future use;
Curtailing peak demand on water treatment and distribution systems;
Reducing wastewater flows to overloaded wastewater treatment facilities and reducing the potential for water pollution;
Enhancing the potential to continue certain economic activities, such as irrigation;
Saving money on residential and agriculture utility bills;
Providing water for wildlife and recreational needs.

Source. Texas Water Development Board

Water & Brownsville A Closer Look

Brownsville lies near the end of the line for the Rio Grande. Average per capita water use in Brownsville is 144 gallons per person per day, while total daily use for the city is typically around 16.5 million gallons. The city's population growth is estimated at 2.5% annually and the city has grown by 24.9% since 1984. Given its location, water conservation at a city-wide and individual level is needed to maintain and extend the water supply. The authority responsible for treating, supplying and conserving Brownsville's water is the Public Utilities Board (PUB). PUB operates two water treatment plants with a daily capacity of 20 million gallons. Brownsville presently has 28,126 acre-feet per year of water rights. Through various agreements the city has increased its total water supply to 34,164 acre-feet. This additional amount consists of 892 acre-feet of class A irrigation water; 1,038 acre-feet of raw water provided by the El Jardin Water Supply, and; 5,000 of acre-feet that comes from the Brownsville Irrigation and Drainage District (BIDD) under a contractual agreement that ends in 1998. PUB is currently negotiating an extension of the BIDD water supply agreement.

Water Loss

Unfortunately, the city's water supply faces pressures not only because of growing demand, but the supply is also impacted by system-wide water loss. Water loss is due to unintentional losses like leakage, evaporation, unregulated use as well as use of water for periodic cleaning of water systems. PUB considers two types of water loss, or unaccounted-for water: raw water losses and treated water losses. Both occur after water is pumped from the Rio Grande. Raw water, as its name implies refers to water lost prior to treatment.

The majority of water loss in Brownsville is related to underground pipe leakage which makes up more than half the water lost. A recent 1993 leak detection study estimated that the PUB system was losing 1.2 million gallons per day, or a third of the total water supply. In response to these losses, PUB created an on-going leak detection program and expanded repair and metering plans. While there is insufficient information on current water losses, one private engineering firm, contracted by PUB, reported that unregulated losses of raw water could cost PUB $864,000 annually (NRS, 1993). This cost does not factor in energy expenditures for pumping, operation and maintenance.

Some large volume water users acquire raw water directly from Brownsville's resaca system which Brownsville historically used to transport raw drinking water from the Rio Grande to the water treatment plants This diversion is typically not charged to the users, or only minimally charged. Brownsville Country Club, for example, extracts an average of 500,000 gallons of raw water each day directly from Resaca de la Guerra. This amount could provide water for 3,496 persons, or three percent of Brownsville (NRS, 1993). PUB argues that raw water loss may be overstated, since the unmetered water is used by residences and commercial interests. Further, if Brownsville chooses to support golf courses, it is cheaper to use raw water.

Still, PUB has taken steps and spent millions of dollars to install new meters and pipes to better monitor water use. PUB set a goal to reduce system loss to ten percent. This would decrease raw water demand to 1,400 acre-feet next year and eventually rise to 4,000 acre-feet annually by 2014 (PUB, 1994). Reducing system loss could lower per capita municipal water use by 8.6% and reduce consumption from 145.3 gallons to 132.8 per person per day (PUB, 1994).

PUB plans to install meters to improve monitoring of raw water usage. In addition, PUB has been replacing deteriorating cast-iron waterlines with PVC pipes to reduce corrosion and water losses. The agency has also increased inspection of 2-inch water meters and created a leak detection program. Last year, PUB constructed a 36 inch raw water pipeline last year to move water from the raw water pumping station to PUB's Water Plant No. 2. This replaces the resacas as Brownsville's primary water conveyor and reduces the risk of contamination and unregulated loss. Moreover, the use of the pipeline reduces water volume and water turnover in the resacas. The makes the resacas more stagnant and lowers water quality. The end results is that less good quality water in the resacas impacts their important role in Brownsville's quality of life.

PUB is also providing free water displacement devices for toilets. This device, also known as a "water bank," saves water by not allowing the tank to fill up completely. The water bank can save 2.8 gallons per flush with older tanks. The utility also supports an education component to provide in-services to school and local businesses. This outreach is to improve water efficiency and conservation and generally educate the community about the value of water resources.

Projected Demand Growth

PUB created a forecasting model to predict future raw water demand scenarios. This model incorporates several variables including predicted population and customer growth, water use patterns, and system losses. The raw water demand factors into all water use including irrigation, municipal, industrial, as well as water needed to maintain and operate the system and water that is diverted into resacas.

Low growth raw water projections by PUB show that demand will grow by 45 percent over the next twenty years, or by two percent per year. This implies that 39,761 acre-feet will be needed by the year 2014. According to PUB's high growth estimate, 51,285 acre-feet will be necessary to meet water demands by 2014. Using PUB's estimates for growth, given firm water rights of 34,164 acre-feet, demand will exceed the upper limits of Brownsville's water rights sometime around 2008. This estimate assumes that the BIDD contract can be extended beyond 1998 (PUB, 1994).

This model clearly demonstrates that Brownsville needs to acquire additional water sources to meet long-term water demand as well as use existing supplies more efficiently. In response to the expected supply shortfall, PUB has proposed various options to obtain more water. These options are in addition to actions currently underway such as purchasing additional water rights, improving system efficiency, reducing water loss, and promoting community-wide conservation.

Water Use Permit 1838

An additional source of water was secured last year when PUB entered into an agreement with TNRCC and the Brownsville Navigation District (BND) to divert water flows to Brownsville. This agreement transferred Water Use Permit 1838 from BND to PUB allowing PUB to pump water when streamflows into the Gulf of Mexico are more than 25 cubic feet per second (PUB, 1994). This option, however, does not provide a dependable source since only 17,000 extra acre-feet have historically been available. Since January of this year, Brownsville received 436 million gallons of water under Permit 1838. Several concerns exist with this source including the mechanics of storing additional water supplies. In addition, use of this water may have a deleterious environmental impact by reducing fresh water flows in the river below Brownsville to the mouth of the river. If water flows are decreased too greatly, this can harm riverine and aquatic habitat dependent upon a certain stream level and water quality (See water and wildlife section).

Underground Storage

One possibility to store the excess supply under Permit 1838 may be to develop underground storage capacity proposed by PUB. This project is known as the Aquifer Storage and Recovery (ASR) technique. Under this proposal, PUB would pump water, treat it, then store it underground for future use. The estimated cost of this approach would be $2.8 million. The State of Texas has provided PUB with a grant of several hundred thousand dollars to study methods to advance the ASR plan.

This method generates concern about the potential mixing of surface water with brackish groundwater. PUB's response has been that underground storage can create "a bubble " of fresh water that will displace the brackish water. While there might be some water loss and some water treatment may be necessary, PUB minimizes the risk.

Groundwater

During the drought of the early 1950's, the city of Brownsville drilled a series of seven wells west of the city to meet water needs. Although these wells remained operable until 1973, the city last used them in 1956 due to the brackish quality of the water. Although PUB is not currently considering using this water, it may reconsider the issue in the future. The Texas Water Development Board recently provided PUB with $130,000 to evaluate the use of the groundwater.

In 1983, the Texas Department of Water Resources identified a source of "acceptable-quality" groundwater twenty miles west of the city. PUB commissioned several test wells. This study drilled a total of 12 test wells. Their findings suggested these groundwater sources could supply up to 10 million gallons per day for a period of 30 years. The cost of developing this supply was estimated to be $17.2 million. These wells could provide a dependable source of water independent of the Rio Grande.

Seven years later, a 1990 report by the Texas Water Development Board (McCoy, 1990) expressed numerous concerns about ground water. The report focused on the poor quality of the water, particularly the detection of chloride, sulfates, boron and dissolved solids. These constituents exceeded Texas Health Department recommended drinking water standards to such a degree that the report stated even mixing ground water with higher quality surface water was "unfeasible". The report noted that using electrodialysis or reverse osmosis could allow ground water's use as augment to public drinking supplies. An additional concern of the McCoy report was the potential impact on Rio Grande river flows if ground water is developed. According to McCoy, increased development of ground water could result in lower river flows in Cameron County.

Channel Dam

More than ten years ago PUB and the Rio Grande Valley Municipal Water Authority applied to the Texas Water Commission, now TNRCC, to construct a dam four miles southeast of Brownsville to impound Rio Grande water. This proposed dam would capture 40,000 acre-feet, or 34.2 billion gallons, of water annually. PUB would receive a minimum of 40 percent of this supply, with the remainder to be shared with Mexico. (Williams, 1990). The cost to PUB would be around $11.4 million.

This proposal has been very controversial due to its potential impacts on water quality and riparian and estuarine ecology. Habitat would be affected above and below the proposed reservoir. The dam would reduce water flows downstream, while impacting streamside habitat and water quality for forty-two miles upstream of the dam.

This reservoir has been criticized for its potential impact on salinity levels (Frye and Curtis, 1990:55). Agriculture and water districts have expressed concerned over increased saline levels in irrigation water, while shrimpers fear what the Channel Dam would damage the estuary used for shrimp reproduction (See Water and Wildlife).

Desalination, Water Reuse & Economic Incentives

The option of desalinization periodically surfaces because of Brownsville's proximity to the Gulf. Brownsville has rejected the desalination option due to its high costs. Treating seawater through desalinization costs roughly four times that of treating water from other sources. However, one possible use for desalination technology may be to treat brackish groundwater. This would be less expensive than treating sea water and extend water supplies.

Given the limited supply of water, another option Brownsville might consider is water reuse. In March of 1993, PUB contracted a study to do exactly this. The study looked at alternative water practices, such as substituting effluent for raw water. The authors concluded that it would not be cost-effective to require large volume uses to cease the current practice of direct extraction of resaca water. Given the current drought, PUB has stated that all options are subject to reconsideration.

One concern related to reuse is the capacity of the treatment process to remove synthetic organic chemicals from the water. Therefore, while reclaimed water may not currently be an option for potable use, there are non-potable uses for reclaimed water, such as industrial, non-consumptive agriculture or golf courses. The State may ease restrictions on water reuse and allow PUB to use treated wastewater to maintain the resaca system.

PUB has also adopted the use of financial incentives to promote water conservation. The agency has set a water pricing rate schedule that rewards low-consumption users and penalizes heavy consumption with a higher per-unit rate.

Financial Considerations

According to PUB's own cost analysis, the least expensive option to increase raw water supply is a combination of efforts that extend the BIDD agreement, continue to reduce water loss, and develop groundwater supplies. This option would yield 15,000 acre-feet at a total cost of $0.58 per 1,000 gallons. If the channel dam is developed, instead of the groundwater option, an additional 7,000 acre-feet could be acquired. However, the cost per 1,000 gallons is almost double at $0.90.

Whatever the final decision, the community of Brownsville, like many other Lower Rio Grande communities, faces hard choices in its pursuit of a greater water supply. The steady growth of urban demand is forcing all border communities to examine their supply options. As in Brownsville, the first step should be to reduce water loss through improved system efficiency and a dedicated leak detection program. This will certainly save border residents both money and water.

Resacas in Brownsville are being impacted by urban contamination and development. According to Ramirez, "the absence of scouring riverine flood flows and the contribution of urban runoff have caused some of the resacas to experience significant siltation... In addition to contributing sediment to the resacas, urban runoff degrades the water quality. Urban run-off is a nonpoint source for fecal coliform bacteria, oil and grease, chlorides phosphates and nitrates (Ramirez, 1986)." Housing development in Brownsville has also contributed to the loss of most native riparian woodlands along the resacas.

Taking Action

"We cannot increase the supply of water allocated to us by nature, nor can we completely alter its geographical disparity. Yet it is not necessary to resign ourselves to chronic water scarcity and the suffering it brings. Rather, we must change the way we address limited water resources, protect them and stabilize escalating demand" - Nelson and Sandell, Population and Water Resources.

As the above articles have demonstrated, the water supply for the Lower Rio Grande Basin is uncertain and under numerous pressures due to natural causes as well as to the growing population. If the current growth trend continues, Lower Rio Grande Valley municipal water needs will more than double over the next fifty years.

Growth will increase the competition for water and may contribute to political conflict in the region. The economic disaster caused by this year's drought clearly demonstrates the vital role water plays in the socioeconomic development of the region. Therefore, given the various pressures on the water supply, Basin residents must use this precious resource more efficiently. This will require developing long-term policies and practices for sharing and conserving the region's water supply. Here are some actions that should be taken to achieve this goal.

Pursue Sustainable Water Use

Develop a sustainable balance between the growing water demands and the limited supply must be developed. Achieving this balance will require increased resource planning to meet the needs of municipalities, agriculture, industry and also wildlife and recreation needs. This will require an expansion of conservation programs, and greater investments in water infrastructure such as improvements in irrigation. As part of this effort, it will also be essential to pursue regional and binational resource planning.

Implement the suggestions of the 1994 Uniting the Basin conference which recognized the relationship of water to the region's sustainable development. Participants in this binational and basin-wide conference called for creating a new sustainable development agenda linking economics with social and environmental well-being. They stressed the need for Basin residents to work cooperatively for solutions and for education programs to be developed.

Practice Conservation - It makes sense

Use water in a rational manner by reducing waste and increasing water efficiency. The expansion of conservation programs could extend the water supply by as much as 25 percent in Basin homes, farms, businesses, and municipalities while still allowing water for recreation and wildlife.

Implement municipal conservation programs which will save water and save money by reducing energy bills and the need to expand water treatment. Implement municipal leak detection programs which will eventually pay for themselves by reducing significant water loss.

Implement industrial water savings programs. Industries such as Levi Strauss in Harlingen and Chem-Pruf in Brownsville are taking a lead role in water conservation by recycling water at their plants. This saves the companies money by reducing water treatment costs and benefits the entire community by extending the water supply.

Take Personal Responsibility

Each one of us personally should try to reduce our own water use by installing water efficient toilets, showerheads, and washing machines. We should plant low-water use plants in landscaping and change water wasting behaviors such as watering the lawn in the middle of the day. Encourage changes in local regulations that would allow use of washing machine water to water landscaping and garden plants.

Save Water on the Farm

Look for ways to use water more efficiently in agriculture such as raising low-water use crops and reduced tillage. Apply available technologies, such as soil monitoring devices, furrow diking, and surge irrigation, which could increase water efficiency by 10 to 15 percent. Since agriculture consumes the majority of water in the area and will remain the dominant user into the near future, farmers must have an essential role in water conservation.

Regional & Binational Planning

Continue and pursue policies and actions cooperatively between farmers, cities, industry and recreation and wildlife interests for regional water management. As the largest users, farmers and municipalities especially must continue to address their common interest in sharing the water supply and using it more efficiently. Finally, because the Rio Grande serves two countries, it is essential that binational efforts to conserve water be expanded.

The water supply can only become sustainable if all residents do their part to reduce waste and rationally consume this precious resource.

This article is reprinted with permission from National Audubon Society's Population-Environmental Report ofthe Lower Rio Grande Basin magazine: National Audubon Society, Sabal Palm Chapter, P.O. Box 5052, Brownsville, TX 78523; Phone: 210-541-8034; Fax: 210-550-0332.

Contact David Berger via email: dberger1@hotmail.com

PLANETA.COM GUIDES

Eco Travels in Mexico

Borderlands Guide