We’re told that hundreds of fish died at Sloan’s Lake because the oxygen levels in the lake became dangerously low. Why did the oxygen levels become so low in the lake? Well, we get a familiar explanation from: “The experts [who] said they think the decreased oxygen levels occurred when algae began dying off as nighttime temperatures fell below 40 degrees.
“The dead algae ended up at the bottom of the shallow lake where it was consumed by bacteria and microbes that essentially sucked the oxygen from the water, said Ellen Dumm, Denver’s environmental health communications director.” (Rocky Mtn News, Hector Gutierrez)
Hmmm… “…dead algae…consumed by bacteria and microbes…that essentially sucked the oxygen from the water…” Sound familiar? An earlier entry, “Ducks Dying…,” includes the following:
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–if only to remind us of the additional scourge brought on by this pollution–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.
Okay. So, it appears–after the initial entry of “Denver’s Parks – A Killing Field“–the deaths of hundreds of ducks at Denver park’s lakes, was exacerbated by “graywater” effluent being pumped into those lakes.
Back to Sloan’s.
A story appearing in the October 19th edition of the Rocky Mtn. News notes: “On Thursday [October 11th? 18th?] the Denver Parks and Recreation Department worked with Rocky Mountain Ditch to open flood inlets to allow more fresh water to enter [Sloan’s] lake. Environmental and parks officials said they believe hundreds of fish swam toward the western shore [of Sloan’s Lake] because the lake’s oxygen levels had fallen considerably, killing many of the fish.”
The “…western shore…” of Sloan’s is where this supposed “…fresh water…” enters the lake via what is known as the Rocky Mountain Ditch.
Comes a post from Toxic Sleuth with regard to Rocky Mountain Ditch, the headwaters of which are within the Coors Brewing operation in Golden. The post reads, in part: “Also curious is that none of the news agencies in Denver have reported anything about the fact that the sole source of the water to Sloan’s Lake – the Rocky Mountain Ditch – is operated by a wholly-owned subsidiary of the Coors Company. The ditch originates on the Coors complex between two of its industrial buildings in Golden. In years not so long ago, even an inexperienced reporter would have inquired of Coors or state officials if they might have had a toxic release that meandered down their ditch to enter the lake at precisely the point were all the fish were dying. The question certainly should be asked, since Coors’ illegal toxic release incidents have become commonplace over the last couple of decades, killing hundreds, even thousands of fish downstream from their industrial operations.”
Okay. Curiously, Denver’s web site, DenverGov , describes the Rocky Mountain Ditch as:
The Rocky Mountain Ditch and Lake Park a part of more than 100 year-old ditch watering system, meandering many miles from Golden through Denver, and ending at the Rocky Mountain Lake Park near I-70. The ditch provided water to a mainly agricultural area in the past, but over time, its users have dwindled mostly to farming in Golden. The City of Denver is considering acquiring the ditch to provide for its maintenance as it affects the homes of many citizens throughout Denver.
The ditch system runs both above and below the ground from Golden feeding Rocky Mountain Lake Park. This lake is maintained by Denver’s Parks and Recreation department, who are working on improving the lake water quality and fish wildlife, one important phase of this expansive system project. [This information on the city’s site is dated, 2001, and emphasizes a remediation project completed on or about October, 2001.)
The city’s information with regard to the Rocky Mountain Ditch mentions nothing about it feeding Sloan’s Lake and, also curiously, places the ditch’s location–within the city limits–from 38th Avenue north. Sloan’s Lake is, of course, significantly south of 38th. However, Berkeley Lake is within the city-noted boundaries of the Rocky Mountain Ditch. Does Rocky Mountain Lake feed Berkeley Lake? I don’t know. Another question: Has this so-called meandering Rocky Mountain Ditch been modified, re-channeled over the years, in such a way that only Sloan’s Lake receives the influx from the headwaters within the Coors complex, and Rocky Mountain Lake–because of said modifications or re-channeling–does not? Again, I don’t know.
The point, of course, is why didn’t the fish in Berkeley and Rocky Mountain Lake die of suffocation from the effects of low overnight temperatures killing algae [as the “experts” assert] as did the fish in Sloan’s Lake? Again, I don’t know.
What I do know is that lake management within the City and County of Denver sucks. I also know that Sarah and I visited Sloan’s Lake last week and found dead fish within the inlet where, supposedly, “fresh” water was being infused into the lake. Witness:
And, of course, leave it to the City’s Department of Parks and Recreation to provide a head shaking moment, a ridiculous response to the situation:
Methinks, No Shit! Sherlock! If only they had left out the “ing” in “Fishing.” Now, that would have made some sense. (Thanks, Jeffrey!)
George In Denver 
In reality, the effluent from the Coors plant barely makes it as far as Sloan’s. Most of the water that feeds the lake is from runoff these days, in Edgewater, and Lakewood. As for the Denver Parks lake management, I agree, there are some serious things lacking. Their statements were almost juvenile compared to the well reasoned thoughts that were published by the Division of Wildlife.
Seems that a bit more collaboration between said agencies would benefit all involved. Before, not after things like this happen.
Thanks, Patrick. Admittedly, this Rocky Mountain Ditch issue is something I know very little about. I suspect that the effluent feeding Rocky Mtn. Lake and Berkeley is also mostly from runoff…thus the presence of elevated mercury levels in both those lakes.
George, researching cities foul up of the rehabilitation of sewers in the neighborhood led me to dig into the Sloans Lake incident. Once searching that I ran across your postings.
Here’s some info for you.
Denver Parks and Recreation (DPR) has sent me what they said was the final report (Oct 22th 2007)on the incident. For the most part it revealed nothing different than what was reported by the media with the exception of the fact that apparently no fresh water was let in through Rocky Mountain Ditch. Still what they did report needs some looking into. If you want I can send you their full press release.
“DPR( probably Lenny Manzanares) did contact the Rocky Mountain Ditch coordinator to enquire as to whether they could supply fresh water to the lake. It was not possible at this time.”Jill McGranahanDPR
The media reported (both channel 9 & 7) that fresh water was supplied to the lake through RMD. That’s Denver media for you..they essentially took the PR release that was spun to minimize the significance of the problem in the first place. I guess someone just made that part up because it sounded good.
In any case the fish probably did run to the inlet because (what little water was coming in and regardless of the were it originated) it was probably more oxygen rich in that area than any other part of the lake at the time.
0.5mg/L-O2 of Dissolved Oxygen is zero oxygen and for all intents and purposes means the lake was dead.
Unless you’re an aqua culturist you wouldn’t be able t understand how bad 0.5mg/L-O2 and even the 5mg/L-O2 ( Colorado Dept of health water quality standard) is and unless you did some research you wouldn’t know how much DPR stepped on their press release to hide the significance of the problem from the public.
Even at that what DPR did put out should have raised some prompted the reporters to at least ask some questions.
What the DPR and the media didn’t report was:
“Denver Parks& Recreation reported that Dissolved Oxygen reading was at 0.5mg/L-O2. throughout the water column”.
That means from the bottom of the lake to surface and that’s important to know. Colorado Dept. of Heath has been sampling 5 different spots in the lake (6 counting the inlet) on a regular basis since 1996. Sloans and two other lakes are Hypereutrophic.
Here’s the kicker: “Acceptable” according to CDHE is a number relative to the average from 15 other Colorado lakes at that number is 5mg/L-O2 . So even by that standard the water quality in Sloans Lake in October was 10 times below its allowable level. Dissolved Oxygen level is an indicator of lake health..but not the only one.
Here’s the real numbers from the EPA are:
6-15=OK
4-6mg= Stressed
2-4mg =Choking
1-2mg =Dying
0-1mg= Dead In other words what DPR put out was a lot of Huey. To read up on the subject go to this site:
http://www.epa.gov/glnpo/glindicators/water/oxygenb.html
DPR reports: “Levels below2mg/L-O2 will stress warm water fish and likely start causing mortality when other stress factors are included (i.e. injuries, age, limited food)”.
The EPA has it that Stressed is 4-6mg/L-O2 not 2mg/L-O2. 2mg is choking and 0-1 is dead.
Stress injuries don’t come from “fish on fish violence” or waterway collision…the injury instead is to the gills and that comes from ammonia. In small amounts, ammonia causes stress and gill damage. Fish exposed to low levels of ammonia over time are more susceptible to bacterial infections, have poor growth…. University of Florida, Institute of Food and Agricultural Sciences.
If you look back in their reports ( http://www.denvergov.org/EAP/WaterQualityProgram/WaterQualityReports/tabid/424855/Default.asp)you’ll find that at times ammonia levels are higher than acceptable l. Yet they always diminish the importance of the data by adding the words “relative to other lakes” or “on average” “within the percentile”.
Then 4 years out of 8 Dissolved Oxy levels were below the 5mg acceptable level and in the other years when it was went above 5mg and it was only at the very surface of the lake where oxygen dissolves into the water. 3 years above 8mg/L-O2 yet a depth it was still stressed. 2003 for some reason was an exceptionally good year when even at 4 feet 6mg/L-O2 was recorded. The lake is barely making the grade even in the best years, it’s sick and their best efforts have not been able to save it.
E-coli readings were off the hook for portions of 2007.. In May they were nearing the advisory level of 250 cfu/100 ml and from July 5th to the 10th , above 750 at the boat ramp and dock ,while around 600 mid lake and just above 250 at Mid Cooper. The rest of the year E. coli levels barely registered. This could indicate that some other type of event is making this happen. They haven’t published their the report on the other readings in other months and probably wont. The reports that you can find on line now only reflect a few months out of the years. So it’s not going to be within the average person power to get data an make a determination.
Through my reading these reports they explain these spikes in readings by single events like rain storms and the Dragon Boat Race…stirring up the lake. Yet their data tends not to support their theory. In October there was no Dragon race but temps did drop. The Regatta takes place on 28th and 29th July and the readings taken then and the day after don’t suggest and impact on the lake stirring. Something happened in the dock and boat area from the 5th to the 10th of July to cause the e.coli levels to spike. In regard to the fish dying in October the logical inference would be that the lake was already being choked by an algae bloom maybe Mid Summer- to early Autumn and that the drop of temp in October just levied the final blow. Everybody seems to be missing the fact that it’s the stuff that is getting dumped in the lake that’s killing it.
DPR:“Because the lake is so shallow and easily mixed, this resulted in no oxygen throughout the water column”
But they never get to the root of the cause.
Now..one report has the inflow from Rocky Mountain Ditch at only 25 gallons per minute and the outflow at 75 GPM(June/July 04). That would indicate to me that water is entering into the lake from somewhere . Granted it could be from rain or run off. Without a more complete hydraulics report on the lake no one will ever be able to tell.
My mother’s North High School civics class (back in the 40’s) taught her that Sloans Lake was born while a farmer digging a well hit an underground spring. So I’d say that some water comes from the spring and some from Rocky Mountain ditch and some from run-off .
I know for a fact that there is a quite a bit of ground water activity to the north and upstream from the boat docks. I know because I dug up our sewer. I know for a fact that the ground water caused 625 feet of our sewer main to fail taking with it several private taps. I know this because I’ve got all the city records including their video inspections. The biggest problem for these sectional pipe sewer systems that we have around here is ground water. It causes them to fail …long story short this equates to exfiltration of sewage into the ground water. It’s for that very reason that the city of Denver is rehabilitating the sewers in our area. I know this because the method that they are using is CIPP Cured in Place Pipe and its design purpose is “ to reduce infiltration and exfiltration caused by ground water”.
Yet while they have been taking steps to reduce this infiltration and exfiltration problem they aren’t doing it correctly..not even by their own standards.
Their leaving voids in the subsoil…( that are in actuality sinkholes) their leaving broken lateral connections on the city side and not protecting the connection from failure of the sewer main failure. Worse yet they not telling anybody about it. Then when the private connections fail (which they does inevitably)….they blame it on the private line. Keeping hush about it and by declaring it a private line issue they force homeowners into repairs costing 5k to 10 k+ . In other words just by waiting they can turn a loss to their budget into revenue maker. No one’s the wiser…because …nobody (the public) can know what’s has gone on or what’s going on underground. Until now.
The city agency that is supposed to take care of the water quality in our lakes is the very same
Agency (Public Works Water Quality Control) that is responsible for the protection and code enforcement of the work on our sewer system….their enforcing code on the private citizen but not on themselves.
The problem is that there is just simply too much money riding on it for the City to fess up… First, If the city cant keep within EPA standards they loose their Federal Money…The air Quality issue is once again menacing that money already (that’s why Ritter is going through his motions right now). Second, there’s too much money to be made on this problem if Denver is able to keep the problem under raps.
For example in our ally since 2003 homeowners repairs of the sewer have cost $22,000.00 ($8,000.00, $10,000, and ours $4100) . The fees…street cut permits ..taxes on these repair are about $1000.00 average ea. The 625 feet of CIPP liner rehab cost the City $12.500.00. When the 6 other taps that were damage by the main failure do fail….the city will recover about half of what it spent on the rehab. Yet at the same time costing the homeowners collectively tens of thousand of dollars more
The inspector that came out to our site told me(on tape) that in Denver there are 2 to 3 dozen of these failures a day….that translates into a lot of money for the city and plumbers.
The craziest thing about it is that the proper repair only cost about $300.00 per tap if they do it while their in there rehabbing the main line.
Many other cities (like San Diego for just one example) for years now have known about the problem…taken responsibility for it and are making the proper repairs….saving their water ways and taxpayers lot of money…The very same company that’s doing the work for Denver has done work (the right way) for San Diego as well as these other municipalities. As to say that it’s not of question of the lack of technology or that the process is to expensive.
If your interested I can give you video audio and docs…
Thanks BL
Thanks, BL. Tried to follow-up with you and found that my IP address had been blocked by your email service. Would like to share your discourse with other blog sites, but would like to have your permission to do so.
Thanks, George
Great follow up BL! When I was volunteering with DOW some years ago there was a similar problem in a lake over on the western slope. The “cure” was to put a sort of bubbler in that infused oxygen into the water. I wonder if something similar could be used at Sloan Lake?