Submitted by Leon Benham
In the March 11th issue of the Imperial Beach weekly Eagle & Times newspaper researchers in the Tijuana River Valley (TRV) outlined the five years of research to determine the cause of death for specific trees. The lead assumption that the cause of death was by the invasive Borer Beetle. Unfortunately, they failed to recognize a symptom of tree loss rather than the cause. The Borer Beetle was a symptom of a tree which was already under severe stress from a process called asphyxiation, also known as ground soil asphyxiation¹. The asphyxiation is caused by standing sewer water.
What the researchers failed to consider is that this was brought up more than 6 years ago by the EPA and by a local geologist Gary Vargas. Asphyxiation is where the oxygen is stripped out of the soil by organisms which feed on the high concentrates of nutrients (standing sewer water). During their brief lifespans these microorganisms strip oxygen out of the soil. The plain truth is that the trees in the TRV were already dying when the Borer Beetles started feeding on the trees. The Borer Beetles will first attack the weak trees which was caused by the standing sewer water. This is supported by their own research when the researchers described which trees lived and which trees died…“ they infested and killed willow growing in or near the main channel significantly more than willows growing far from the water. On the wet site the mortality rate was high, and on the dry site the willow mortality rate was low.” Strong trees have the strength to defeat the borer beetle – but weak trees get consumed.
When the river water was diverted in the early 1980s and the water was spread over the valley the amount of standing water in the valley increased by over fifty times in size compared to the historical norms. In the past, during an average rain year there was very little standing water in the TRV. This was because the County of San Diego practiced good river mosquito control “best practices” (No Standing Water – learned during the construction of the Panama Canal). Historical aerial photographs show that after a normal rain event the water almost entirely flowed to the ocean with extraordinarily little standing water left behind. However, in the early 1980s because of incorrect interpretations of the river’s ecology by ecologists, the water was intentionally spread out over the valley. Additionally, manmade ponds were built and now standing sewer water was introduced to the valley year-round (Sheldon’s Pond and Goat Canyon). The 180 acres of standing sewer water pond between Hollister and Dairy Mart Road which creates the acrid smell of sewage is a good example of this man-made phenomenon. The ironic fact is that these little microorganisms which eat the sewage also produce methane gas which produces 10 times more harmful greenhouse gases than carbon dioxide. In contrast, when the sewage water goes to the ocean the plankton which feed on the sewage nutrients create more oxygen and far less methane.
Another point that the environmental researchers got wrong was the description of the “native riparian forest in the Tijuana River Valley.” This characterization is misleading and the historical photographical evidence proves that. It is clear from aerial photos in the early 1900s and later that the land which makes up the 3700 acres was approximately 85 percent coastal scrub, 10% estuary and 5% dry river bed. There were very few trees in the valley except directly next to the river and virtually no wetlands beyond the Imperial Beach estuaries normal high tide mark. The Riparian Forest is not the natural ecology for the Tijuana River Valley and the recommendation of these researchers not to remove the dead fallen tree brush is bad river maintenance practice because it stops the flow of water, increases the accumulation of trash, creates mosquito habitation, and stops natural sediment transportation to the ocean. When the Tijuana River Valley is compared to other natural river systems – in San Diego County and North Baja California – this false idea of a large forested Riparian habitat is proven to be a wrong characterization of the TRV ecological habitat.
Now with more than 40 years of experience behind us, what is the result of these environmental practices which allow standing water to accumulate in the Tijuana River Valley? The TRV natural environment in both the water and sediment transportation system is severely compromised. The once abundant California quail (our State Bird), lizards, horny toads and tunnel dwelling owls are gone. The insects which would feed the nighttime feeding bats are in such low numbers that the bats are gone. These bats are critical to the lifecycle of nighttime flowering plant species which use to cover the north facing hillsides of the TRV. Because the bats are gone these types of plants are now almost nonexistent. These large plants with their root systems would hold up the sediment from coming down the hillsides. The result of losing these plants is more sand and sediment in the river. The standing water which now contains sewage does not run quickly to the ocean instead it sits in large ponds under Hollister Road and elsewhere in the Valley. During the warmest part of the day, the smell from the manmade sewer pond at Hollister Road will activate your gag response.
Worst yet for the TRV environment, the standing water now requires county mosquito control. Over the past decades the county has sprayed Malathion from helicopters on repeated occasions and now “Vector Control” spreads granulated mosquito pellets in the water to try and stop the mosquitos. This has been a disaster to the natural environment. According to German researchers they are finding about 70% of their insects are gone because of this type of granular biocide. Many of the insect species specifically the bees, monarch butterflies, dragonflies and numerous other insects that drink the same water. As a result of these water-based granular biocides, almost all the insects’ reproduction cycles are severely compromised and from my experience about two thirds of the insects do not reach maturity. It is clear to understand why the once abundant animal life including ducks, quail, lizards, horny toads, frogs are now not present in the environment of the TRV. The food sources these animals once depended on is now gone. Dead and fallen trees in the TRV, when examined, have few insects consuming the trunks. The normal decay of the trees is being stopped because the water kills the insects and larva that consumes them.
Almost all residents and ranchers who live in the Tijuana River Valley and next to the Imperial Beach Estuary clearly see the short-sighted decisions that were made in the Tijuana River in the early 1980s were a disaster for the ecology of the TRV. These decisions have caused a multitude of problems including replacing temporary vernal pools of water with permanent standing ponds of sewer water, sediment accretion (the IB estuary has lost nearly 90 percent of its tidal flow), loss of sand to our beaches and loss of viable habitats.
The simplest, most cost effective and natural restoration of the Tijuana River Valley is a thorough cleaning and regrade of the riverbed. This would include the removal of manmade debris, removal of tires and trash from the site between Hollister and Dairy Mart road. Also, this should include the restoration of rivers flow to its single native riverbed including restoring the flow of water from coast feeder streams of Smugglers Gulch, Goat Canyon and other natural drainages which bring large amounts of water to the Tijuana River which provide the energy to transports fresh sand and cobbles to our beaches. This natural sediment transport historically supplies 655,000 cubic yards of material to our shorelines, which naturally protect our coastal homes and provide the world class surf break off the Boco Rio.
It is no wonder scientific studies have been critical of river habit restoration in the United States and Europe. These studies are made by the very best minds on environmental science. In 2015, the findings were made public that of the $70 billion spent in the United States over the last 20 years on environmental river restoration about 90 percent had failed in reaching their stated goals. 2 The odds in fact are bleaker than that. Of the 78 river restoration projects examined “only two showed statistically significant increases in biodiversity.” That is only a 2.5 percent “success rate.”
Think of it? The State of California is relying on a group of NGOs and environmental groups who have no experience in restoring habitat, do not live here in the TRV valley, who cannot and do not observe or comment on the obvious things screaming out from our environment and have a track record of over 90 percent chance they will get it wrong.
The current opportunity of the federal/state funding to restore the TRV is now. We do not need any more studies which last decades and come to no conclusion. It seems clear what needs to be accomplished in the TRV and in our local environment. The citizens who make up our communities of the Chula Vista, Coronado, Imperial Beach, Nestor/Egger Highlands, and San Ysidro ask for our state/county and city governments to listen to the local citizens and to provide a fresh approach to the restoration of TRV and coastal ocean environment.