Environmental Issues Around the Sea

---

Water Quality	Salinity Nutrients
Importance of Wildlife	The "Little Critters" Fish Birds Wildlife Management
The Broader Context	Air Quality Colorado River Delta California's Water Allocation The IID/San Diego Water Transfer TMDLs

---

Water Quality

Outdoor enthusiasts have long enjoyed the recreational opportunities provided at the Salton Sea, including boating, fishing, and camping.  Hundreds of species of birds have depended on this oasis in the California desert as an important wetlands habitat, as one stop on their journey along the Pacific Flyway.  The agricultural community has benefited from the Sea’s existence as well, relying on the Sea as a reservoir for agricultural drainage. At present, certain environmental issues have to be addressed in order for the Salton Sea to continue serving the outdoor enthusiasts, the hundreds of species of birds, and the agricultural community.

A major issue being addressed in the restoration project of the Sea is water quality.  Because of its use as an agricultural sump, concerns have been raised as to the presence of harmful elements in the water, elements such as toxics, trace metals, and volatile organic compounds (VOCs).  Results from scientific study, however, show that these and other chemicals used in agriculture have not been detected at levels that are above established safety standards. Two issues that are of concern are salinity and the nutrient levels of the Sea.

Salinity

The Sea derives its name from what is now so abundant in its waters - salt.  When the Salton Sea formed in 1905, it was a freshwater lake.  Over the years, the water has evaporated, leaving behind high concentrations of salt.  Today, the Colorado River is pumped for agricultural and urban use throughout its length and by the time it reaches Imperial Dam, while still considered “freshwater,” it already contains high levels of salt. Farmers in the Imperial and Coachella valleys use more water than required by the crops to flush out salt buildup in the soil, bringing in significant new water to sustain the Sea, but also bringing in additional salt.

The issue of salinity has become a major focus because it is reaching a level where it is likely to interfere with fish reproduction and, ultimately, survival.  Loss of fish would greatly impact the Sea’s productive sport fishery, and the food source of fish-eating birds that flock to the Sea.  

Current inflows to the Sea are equal to the amount of water lost in evaporation and Sea levels are stable.  But each year roughly 5 million tons of new salt are added to the Sea in those inflows.  To stabilize salinity levels in the Sea, at least an amount equal to the new salt must be removed so that salinity levels don’t go higher.  If relatively freshwater now being used on farm fields and flowing to the Sea is conserved and transferred elsewhere, significantly more salt will have to be removed to lower the concentration of salt in the remaining water in the Sea.

One option to be used to reduce salt is solar evaporation ponds.  Engineering analyses suggest that they can remove the most salt at the least cost.  They do have several drawbacks:  they will require large amounts of space for the ponds themselves, they will add to the loss of water in the Sea as they evaporate water to capture the salt, and they will result in salts that will need to be disposed of.  They also offer several advantages in addition to removing salt.  Their configuration could be used to displace water in the Sea and thus help maintain water elevation levels.  The ponds themselves can offer new kinds of habitat for birds.  And, if the ponds are placed on marginal farm fields, they could free up water that would not be used for farming.  Loss of water and salt disposal will be true for just about any practical method used to remove salt.

[Back to Top of Page]

Nutrients

In addition to being highly saline, the Sea is highly eutrophic, meaning that it is full of nutrients. The nutrients come from dying organic matter in the Sea (algae bloom, dead fish, decaying plants, etc.) and from agricultural and other chemicals entering the Sea.  Nitrogen, phosphorus, calcium, magnesium, sodium, potassium, sulfates, and chloride are the most common chemicals entering the Sea.  Nutrients, or eutrophic conditions, do not mean toxic.  Eutrophication is a natural process in all bodies of water as decaying matter accumulates.  In many lakes, including the Sea, the process gets speeded up by human activities.

The high levels of nutrients foster the algae blooms.  Algae bloom and die quickly.  When they die, they pull oxygen from the water, often to levels that deprive the fish of life.  Fish die-offs return nutrients to the Sea as they decompose, keeping the nutrient cycle going. Many consider eutrophication a larger, if less immediate, threat to wildlife than high salinity, but it is a much more complex issue to address.  

Of all the nutrients in the Sea, phosphorus is considered the limiting nutrient.  In other words, if phosphorus levels can be reduced, the eutrophication may be reduced as well.  In recent studies, scientists were surprised to discover that phosphorus levels were only slightly greater today than in the 1960s, even though phosphorus input to the Sea has doubled.  Additional studies are being conducted to determine what has happened to the phosphorus.  Some appears to have precipitated out to the sediments, some is consumed by microorganisms, and some is taken up by tilapia.  Further, the high salinity may be increasing the mineralization (and thus the reduction of nutrients) of chemicals in the Sea.

 As a result of these new findings, scientists are suggesting that the most important first step is to reduce phosphorus inflows to the Sea.  They propose spreading alum, a safe and common process, in  the tributaries to capture the phosphorus before it enters the Sea.  Other steps that could help are to install tertiary treatment for municipal wastewater and to initiate Best Management Practices (BMPs) on farms, fish farms, and feed lots that would reduce phosphorus runoff.  A final step that may help is to introduce fish harvesting to reduce the phosphorus recycling from dead fish.

[Back to Top of Page]

---

Importance of Wildlife

The Salton Sea is an environmentally rich area of high biodiversity, ranging from simple one-celled critters to the hundreds of thousands of birds that use the Sea.  The nutrients in the Sea, the other food sources in the Sea, and the surrounding agricultural fields all support the abundance of life.  As part of the Colorado Desert Ecosystem, the Salton Sea and the wetlands along its shoreline are host to life in many, and very unique, forms.

The “little critters”

The Salton Sea is a “hotspot” for microbial diversity.  These smaller inhabitants of the Sea, labeled “Little Critters", are responsible for most of the photosynthesis and most of the decomposition occurring at the Sea.  They are a major determinant of water chemistry and, thus, water quality.  They serve as the base of the food chain that sustains the fish and bird populations of the Sea.

Considerable work has now been done to catalog the diversity of “critters” and their effects on the ecosystem, but additional study is needed.  Approximately 400 different species have been identified with dozens that are new to science, including whole new categories of “critters.”

[Back to Top of Page]

Fish

The Salton Sea is considered to have the most productive fishery in the nation, if not the world.  It has been stocked with several salt-water sportfish – orange mouth corvina, sargo, and gulf croaker.  In the mid to late ‘70s, tilapia inadvertently entered the Sea and flourished.  Even though they are subject to die-offs from low temperatures and low oxygen levels, they breed often and their populations reach high levels.  Currently the number of tilapia have declined, part of what seems to be a cyclical pattern of expansion and decline.  Scientists are studying the population dynamics of the tilapia.

One endangered fish, the desert pupfish, is found in fresh water inlets to the Sea.  Studies have shown that the pupfish do move between habitat areas when a fresh water connection exists.  As the restoration proceeds, maintaining these connections will be important in ensuring genetic diversity and access to habitat areas.

Other nongame fish are found as well – sailfin mollies and carp, for example.

[Back to Top of Page]

Birds

Visitors to the Sea are met with sights of birds among the trees, birds in the water, and birds flying overhead.  The importance of the Salton Sea to these winged creatures cannot be stressed enough. The Salton Sea is a vital link in the Pacific Flyway, as birds migrate along this coastal corridor.   The Salton Sea provides a variety of habitats and ample food sources for these migratory birds as well as for resident avian populations.  Food is readily available from the Sea and the agricultural fields that surround it. 

Due to this inviting expanse of habitat, the Salton Sea is ranked as the second highest birding area in the nation, second only to the Texas gulf coast.  For some species, there is no “fallback” place of the same quality that they could use.  For them, loss of the Sea would mean loss of birds.

There are approximately 400 species of resident, migratory, and special status birds that visit or call the Sea “home.”  In some years as many as 95 percent of the total population of eared grebes may use the Sea, 80 percent of the American white pelicans, 50 percent of ruddy ducks, and 40 percent of the American population of Yuma clapper rails.  Nearly 40 percent of California’s breeding by black skimmers takes place at the Sea, and the nesting colony of gull-billed terns is the largest in the western U.S.

These species plus others are considered of concern at regional, continental, or global scales. Other sensitive species include brown pelicans, the white-faced ibis, mountain plovers, black terns, burrowing owls, fulvous whistling ducks, least bitterns, wood storks, black rails, and snowy plovers. 

[Back to Top of Page]

Wildlife Management Numerous management issues exist on how to best deal with concerns surrounding wildlife at the Sea.  Protecting habitat, usually a major challenge, has not posed a serious problem.

Fish densities provide a special challenge, because, when numbers are high, there is greater chance of die-offs as fish vie for the same fixed supply of oxygen.  In addition, wildlife management involves determining a cost-effective way of cleaning up unsightly remains of these fish die-offs along the shoreline. Fish harvesting, and transporting and disposing of dead fish at a scale of this magnitude requires careful planning. 

Combating bird disease is another high priority, because of the large populations of sensitive species that make use of the Sea.  Although bird diseases have been reported since the ‘20s, the number of deaths due to these diseases began rising after 1987, as they have around the world.  The Authority has initiated a wildlife disease program, having full time researchers at the Sea study the incidence and cause of bird deaths. The recent addition of an "emergency room" at the Sea which can treat sick birds and send them to bird "hospitals" has allowed roughly two-thirds of the sick birds to be rehabilitated.

Because of the loss of inland wetlands in southern California, the Salton Sea has become an unplanned mitigation wetlands.  Birds depend on it and flourish because of it, regardless of its origins, its natural “purity,” or its problems.  They don’t know or care that the source of the water in their wetlands has come from cities and farm fields.  That is similar to growing numbers of situations all over the planet where wildlife is now dependent on human-altered landscapes.  The Salton Sea offers a classroom and proving grounds for wildlife management to expand its knowledge of how to manage artificial systems with less than pristine conditions to take the place of natural areas that are lost forever.

 As one scientist stated, “The Salton Sea needs to be treated as a garden to be nurtured for the benefit of our avifauna rather than as a compost pile.”

[Back to Top of Page]

---

The Broader Context

Water quality and the role of the Sea in supporting wildlife are essential environmental issues that are being addressed as part of the restoration project.  Restoration of the Sea, however, becomes even more challenging and more complex when set in the midst of changes that are taking place around it – changes that can alter the future course of the Sea.

Air Quality

A pending environmental issue is the risk of degraded air quality resulting from the proposed water transfer from the Imperial Irrigation District to San Diego.  Although exact predictions of resulting air quality are not possible without additional information, initial assessments have concluded that significant exposure of sediments could occur.  Both the Imperial and Coachella Valleys are currently in non-attainment for PM10 state standards, a measure of small particles that can be drawn deeply into human lungs, causing respiratory problems. 

As inflows are reduced, the Sea’s elevation drops and sediments become exposed.  Because the Sea is shallow (comparable to a forty foot puddle 1/8 of an inch deep), it doesn’t take much drop in elevation to expose a large amount of sediments.  If the transfer takes place as proposed without replacing inflows, the Sea will drop over 15 feet and expose almost 70 square miles of sediments.

The amount of dust that would blow depends on a number of factors:  the nature of the sediments, the kind of salts that precipitate out in the sediments, the nature of the crust that forms as a result of the salts, the direction and speed of winds, the length of the “fetch” the wind blows across, the availability of larger particles such as sand to disturb the sediments, the amount of other disturbance to the crusts, temperature, and the amount of moisture in the sediments.  The potential for blowing dust can be reduced through mitigation – keeping sediments wet, planting saline-tolerant vegetation, and covering emissive soils with gravel.

However, looking at areas such as Owens Lake or Mono Lake, it is clear that mitigation is complicated and expensive.  The projected cost for Owens Lake mitigation is roughly $300 million.  While sediments around the Sea and other conditions are not expected to be as emissive as Owens Lake, the area of soils exposed may be twice as much.  Conditions around the Sea are highly variable and will blow in different places under differing circumstances.  If the resulting emissions are only 1 percent of the levels at Owens Valley, it will be enough to exceed PM10 standards, standards that are already being exceeded.  

[Back to Top of Page]

Colorado River Delta

The Colorado River Delta in Mexico, like the Salton Sea, is part of the California Desert ecosystem.  The area of the Delta above the Gulf of California in Mexico was formerly an ecologically abundant area: wildlife flourished. When most of the Colorado River became diverted before it reached the Gulf, the Delta wetlands were greatly reduced in scale, forcing wildlife species to go elsewhere for survival.  To restore some of the wetlands, it has been suggested that a surprisingly modest amount of surplus flows from the Colorado River be designated as environmental flows for the Delta rather than be appropriated for irrigation or other uses.  Evidence from recent flood flows to the Delta have shown that if these waters were allowed to flow to the Delta, they would bring back some of the vegetation, provide a variety of habitats, and even provide economic benefits through activities such as ecotourism, hunting, fishing, and improved shrimp harvesting in the Gulf.

The Gulf at one time extended north past the Salton Sea to Indio. The Sea then became an alternative outlet for the Colorado River when the channel to the Gulf became blocked by sediment. Geologically, the two areas are linked.  Birds use both areas as habitats.  Culturally, the same tribes used both areas. Both areas are threatened by nearby burgeoning urban growth.  And both areas now depend primarily on remaining water that has been discarded by humans.  Although linked in many ways, joint management for these critical areas is complicated by national borders, different languages, and competing needs for water.

[Back to Top of Page]

California’s 4.4 Limit

Under the Colorado River Compact, California was given the right to use 4.4 million acre feet (maf) of water each year.  Because other states in the Colorado River Basin were not using their full share of allotted water supply, California has enjoyed a considerable amount more.  Now, those states need to use their full share and want California to use only that water it is entitled to.  To meet the limits of the entitlement, water conservation would have to increase, affecting, among others, the agricultural community.  Because almost 90% of the Sea’s volume results from agricultural runoff, a reduction in water use by farmers would result in reduced water flows into the Sea; reduced water flows would raise salinity levels even more.

[Back to Top of Page]

The IID/San Diego Water Transfer

Because of the pressure to conserve, the Imperial Irrigation District (IID) and San Diego have agreed to a transfer of 200,000 acre feet per year of conserved water to San Diego in exchange for payment.  Although not yet approved, the transfer represents a reduction of 200,000 acre feet of flow into the Sea.  Restoration plans must take into account the lower lake levels and the higher salinity levels that could result.

[Back to Top of Page]

TMDLs

The Environmental Protection Agency is requiring states to enforce a provision in the Clean Water Act designed to set water quality standards based on the total quality of water in a stream or lake, rather than on individual contaminants.  If a stream or lake is classified impaired, then the state must identify all sources of impairment.  The Total Maximum Daily Loads (TMDLs) are standards allocated among all sources of identified impairment, and each source must cut back its contribution to the impairment in order to meet the standard.  The process of establishing standards is just getting underway, but it has the potential to require significant changes in the amount of nutrients, the degree of salinity and other factors.  It is not clear as of yet how this will affect the restoration, but it is something to recognize as possibly affecting restoration activities.

[Back to Top of Page]

Copyright 2000 Salton Sea Authority - All Rights Reserved
Site Design and Hosting by KG WebWorks