Following-up on my original entry, Denver’s Park – A Killing Field, and an additional entry, A Timely Obscenity, both of which dealt with the death of ducks, first in Denver’s parks and, secondly the despicable saga of Scott Clark who ripped the head off a duck in a St. Paul, Minnesota hotel, the following provides the City’s response to allegations that sewage water effluent containing toxic and radioactive waste is being re-routed to Denver’s Park’s lakes, where it is killing hundreds of ducks.
First, we need to understand the term, “greywater.” From this site, comes the following:
Greywater(washwater) sources are found in the kitchen, the laundry, bathrooms/washrooms, sinks, and showers. None of these sources carries water which is likely to contain disease organisms of anywhere the same magnitude as those in toilet wastes.
Historically speaking, it was not so very long ago that lakes, rivers and coastal waters were clean and supported a balanced aquatic plant and animal life. As rivers and lakes started to receive organic pollution from industry, sewers, septic systems, and present -day agricultural and livestock-raising practices, these organics decomposed in the water, consuming the oxygen dissolved in it–oxygen crucial for fish and other aquatic animals. This process is known as primary pollution.
Concomitant with the primary pollution, algae and other “out -of- balance” plant species start to grow as the result of being fertilized by the surge of nutrients from the above-mentioned sources. These fertilized plants, in turn, die and decompose, further robbing the water of its naturally dissolved oxygen. This phase is called secondary pollution (Diagram A), or “eutrophication”, and is considerably more damaging to the oxygen level than primary pollution.
Second, we need to understand what “Avian Botulism is.” From this site, comes the following:
Avian botulism is a paralytic disease caused by ingestion of a toxin produced by the bacteria, Clostridium botulinum. This bacteria is widespread in soil and requires warm temperatures, a protein source and an anaerobic (no oxygen) environment in order to become active and produce toxin. Decomposing vegetation and invertebrates combined with warm temperatures can provide ideal conditions for the botulism bacteria to activate and produce toxin. There are several types of toxin produced by strains of this bacteria; birds are most commonly affected by type C and to a lesser extent type E.
Birds either ingest the toxin directly or may eat invertebrates (e.g. chironomids, fly larvae) containing the toxin. Invertebrates are not affected by the toxin and store it in their body. A cycle develops in a botulism outbreak when fly larvae (maggots), feed on animal carcasses and ingest toxin. Ducks that consume toxin-laden maggots can develop botulism after eating as few as 3 or 4 maggots.
- Type C toxin: waterfowl, shorebirds, colonial waterbirds, and others
- Type E toxin: gulls, loons, and others
Clinical Signs/Field Signs
Healthy birds, affected birds, and dead birds in various stages of decay are commonly found in the same area. The toxin affects the nervous system by preventing impulse transmission to muscles. Birds are unable to use their wings and legs normally or control the third eyelid, neck muscles, and other muscles. Birds with paralyzed neck muscles cannot hold their heads up and often drown. Death can also result from water deprivation, electrolyte imbalance, respiratory failure, or predation.
Okay. I understand. A horrible death.
In response to an inquiry from Denver Citycouncilperson Jeanne Faatz (District 2, Southwest Denver), the Denver Department of Environmental Health provided, on September 24th, that they had received word from the Colorado Division of Wildlife, that duck deaths in city parks are “…in fact, attributable…to Avian Botulism. …There are regulatory requirements through the State Health Department that both Denver Water and the City must comply to use this [recycled wastewater–“greywater”] as irrigation water at our parks.”
Councilwoman Faatz then asked the relevant question: “Am I right in concluding that avian botulism is not and cannot be attributable to recycled wastewater, or can that certainty be stated?”
Environmental Health responded: “That assertion would be correct. The spores that cause avian botulism are naturally occurring in soils and sediment. The high nutrient value of the recycled wastewater and any other stormwater runoff has a secondary effect of promoting algae growth. When the algae die off, it causes a decrease in the dissolved oxygen in the lake which promotes the germination of the spores. It’s kind of a vicious cycle. We have been working with Parks and Recreation over the last few years with our recommendations on lake management, including the recommendation that the lakes need to have better movement to promote oxygen distribution in the water.”
I can’t help here but to suggest that Environmental Health’s response should have begun: “Well, that assertion must be tempered by the following.” It’s the “…vicious cycle…” comment that, for me, qualifies the assertion that greywater effluent is not, at least, a contributing factor in the death of ducks in our parks. It’s that troublesome word anaerobic (no oxygen) that brings me to this conclusion. The wastewater effluent clearly contributes to the anaerobic conditions in the park’s lakes.
Two missives from the city are instructive. First, a background piece from (September 12th) that articulates the city’s view of the originally raised issue:
Background – Dead Ducks in City Park/Lowry Landfill Water
September 12, 2007
[A public interest group has suggested that] the waterfowl deaths in both City Park & Metro Wastewater earlier this year to radioactivity they claim is in the water, which has no basis in science or fact.
First, there is no threat from radioactivity at Lowry Landfill Superfund Site, according to the EPA. After dealing with this theory for years…, the EPA issued a white paper in 2001 that stated in detail there is no radioactivity at Lowry Landfill beyond background levels (100 times below what is allowed in drinking water). In addition, the EPA’s 5-year report issued early in 2007 gives the remediation remedy a thumbs up.
Second, the duck deaths are separate: two different species, two separate set of circumstances. Division of Wildlife and U.S. Fish & Wildlife are still trying to determine the cause of Northern Shoveler deaths earlier in the year at Metro, when it was extremely cold. So far, the research is inconclusive.
The mallards that died at City Park are consistent with avian botulism that has occurred there for many years at this time of year, when the temperatures are hot. The symptoms are consistent with botulism, but DOW tests won’t be back until next week. Avian influenza and avian cholera already have been eliminated. The botulism is not uncommon in shallow lakes and is nearly impossible to eradicate. Almost all the bird deaths at City Park were mallards, which get it from feeding off the bottom of the lake. It cannot be transmitted to humans, pets or mammals. If there was radioactivity, it would have killed off a lot more than ducks. There have been discussions with Parks and Denver Water to aerate/circulate water in both lakes to help the water quality, but it would not eliminate the botulism.
Finally, the “partially treated wastewater” the [public interest group] refers to (that now supplies City Park lakes) is Denver’s recycled water that meets very high standards and will free up enough drinkable water to serve 35,000 homes. Denver Water’s recycled water treatment process is very similar to the process used to treat drinking water, although the end result has a residue of salts and other elements that makes it not drinkable. The production from the recycling plant must satisfy government standards for non-potable water.
In Colorado, the quality of recycled water is regulated by the state health department. This water is monitored and tested below Lowry Landfill, coming into Metro Wastewater, going out of Metro Wastewater, coming into the recycle water plant and going out of the recycled water plant.
Okay. Infusing non-potable water into Denver’s Park’s lakes will free-up potable water for, at least, 35,000 households. If what appears to me to be a contributing factor to avian botulism–greywater effluent–do we then minimize, devalue the affects of the same on the precious critters in the parks so some money can be saved, some costs can be mitigated. It’s not as if those 35,000 homes aren’t already receiving potable water. What I wonder is that cost savings? And, how does one weigh that against the deaths of those precious critters?
Finally, dated September 20th, comes this from Denver Environmental Health:
Dear Ms. ,
We have received your comments/complaint regarding the duck deaths and water quality at City Park. Our department is waiting to hear results from the Colorado Division of Wildlife regarding confirmation of the official cause of those deaths. The deaths appear to be consistent with dieoffs we have witnessed over the past several years. Historically, these deaths have been attributed to avian botulism, a common occurrence in wetlands and lakes. Avian botulism related incidents have been occurring annually at the City Park Lakes for many years (anecdotally up to 25 years). They have been noted by the Denver Department of Environmental Health (DEH) since at least 1997.
Symptoms consistent with avian botulism include a loss of involuntary muscle control which impacts the ability to fly and also the effective use of their legs. This is why botulism infected birds often use their wings to propel themselves through water rather than their feet. Another symptom of botulism is the inability to hold their neck up, a term called limber-neck. This unfortunately often results in drowning.
Many infected birds can be hydrated and cured of the symptoms if treated early enough following infection. Treatment includes provision of shade, hydration and, if possible, injection of an antitoxin. This requires appropriate facilities to hold and treat the recovering birds until they are healthy enough to leave under their own power. There was a report of the Colorado DOW delivering many of the recently infected birds to Wild B.I.R.D. where up to 15 were being rehabilitated from botulism related symptoms (for details: http://www.thedenverchannel.com/news/14106879/detail.html).
Please see: http://www.nwhc.usgs.gov/publications/field_manual/chapter_38.pdf for more details on avian botulism.
Because the deaths were almost all confined to mallards, DEH determined that water quality testing outside of our regular water quality testing cycle was not necessary because of the history of avian botulism at the lakes this time of year and the lack of other atypical conditions.
DEH sampled Ferril and Duck Lakes on August 7. Results from that sample event have not been received from the contract laboratory as of this writing. Those will be posted on our website when we receive them, according to our normal procedure. Here is the URL where we post the results:(http://www.denvergov.org/EAP/WaterQualityProgram/WaterQualityReports/LakeReports/tabid/424858/Default.aspx).
The green color of the water may be attributable to many factors, one of which is phytoplankton communities. The elevated nitrogen level of the re-use water combined with an adequate amount of phosphorus, shallow water depths, un-impeded sunshine, and existing nutrient loads in the sediment are factors contributing to a productive phytoplankton community. Recently renovated lakes often result in algae blooms as a result of the re-suspension of sediment bound nutrients and other factors. There may have also been renovation activities that had impacted the lake color. That is yet to be determined.
DEH will continue to monitor the City Park lakes as deemed appropriate. If you have further questions or comments on this issue, please feel free to contact the DEH Environmental Quality Division at 720-865-5452.
Denver Environmental Health
I don’t know… The city’s response to this issue is certainly reasonable. I know good folks at the city are worried about and working on this issue. Further, I’m inclined to believe that radioactive waste from the Lowry Landfill is not a causal factor here. I do believe, as I said, greywater effluent is a contributing factor to this problem. That can be fixed. One can only hope the city will continue to pursue a solution.
Of course, there’s still the question about elevated mercury levels showing up in Berkeley Lake and Rocky Mountain Park Lake, both in Northwest Denver, both in Councilman Garcia’s district. But, alas, I’m still awaiting a promised “follow-up” from Garcia on another issue I raised in March, 2005. Actually saved the email promising a follow-up. After two years of waiting, methinks Garcia has placed the issue on the backmost burner.
Once again, thanks to Councilwoman Faatz for pursuing this.