Causes of Low Dissolved Oxygen (DO) in Basins 1 and 2 Hypolimnions of Lake Whatcom and Proposed solutions to increase DO and improve other Water Quality Properties

Prelude

Before we get into the details of “Causes of Low Dissolved Oxygen (DO) in the Lake Whatcom and Proposed Solutions to Increase DO and Improve Water Quality Properties” please consider the following analogy to the Lake and try to create a mental picture in your mind.

Let’s take carbonated drinks as an example. You may like drinking cold soft drinks/soda pops, beer, or carbonated water, especially on a warm summer day. What happens when you open that carbonated drink container? It loses pressure and begins going flat. It loses pressure because pressure was used to force, a gas, in this case carbon dioxide (CO2), into the liquid and that contained pressure was higher than the outside atmospheric pressure; which is why you hear a “swoosh” when that pressure is released. At the same time and in the same place, you may also observe that the gas (CO2) begins to “bubble out” of the liquid. As the temperature of the liquid becomes warmer the solubility of the gas in that liquid decreases; the effect of this is that the gas separates and bubbles out of the liquid as it warms.

Like a flat soft drink, flat beer, or flat water, the lake’s water can also become” flat” when it loses its Oxygen/Dissolved Oxygen (DO) bubbles. As flat soft drinks, beer, or carbonated water lose their bubbles these drinks also lose their flavor quality and taste differently. Changes in a liquid’s quality, flavor and taste in this case, are caused by different chemical reactions which result when that gas is lost from that liquid which causes its quality to change. As the Lake loses its bubbles of DO there are different chemical reactions which occur which affect Lake Water Quality.

There are major physical, chemical, and biological causes which decrease/deplete/consume O2/DO concentration in the Lake Whatcom, which we will explore within this article. If all identified causes create a DO deficient Lake, we should be able to logically reason and develop a solution or set of solutions which can address those causes. If Lake Whatcom is deficient in DO, logic would lead us to a solution which uses O2 (Reaeration) to replenish the deficient DO lake. We will use a Problem Solving (Causal Analysis) technique to define the problem, analyze the cause and effects of the problem, develop solutions which eliminate, mitigate, or change each cause, and propose the most cost-effective solutions based upon fact-based, rigorous logic.

Emails EJ Ledet/Clean Flo EJ Ledet Resume Clean Flo Statement Bel Marin – Clean Flo System Results – Published Study

WWU and DOE have used data on Phosphorous, Algae, and low Dissolved Oxygen in Lake Whatcom to drive legislation to increase property taxes, and assess fees in newly created storm water districts to manage P out of Lake Whatcom via implementing Total Maximum Daily Load (TMDL)modeling results. Both WWU and DOE are stating that the main cause for DO depletion/consumption is Algae caused by P inflow into the Lake.

EPA recommends using Causal Analysis Diagnosis Decision Information System, or CADDIS, to help scientists and engineers in the Regions, States, and Tribes to conduct causal assessments in aquatic systems. EPA Causal Analysis is based upon Kepner Trego Causal Analysis teaching (i.e., where a problem occurs vs where it does not occur; when a problem occurs vs when it does not occur, etc.)

  1. https://www.epa.gov/caddis ; https://www.epa.gov/sites/production/files/2015-12/temp-cd_sim_1500.jpg ; https://www.epa.gov/caddis-vol1/caddis-volume-1-stressor-identification-step-2-list-candidate-causes

A Cause and Effect diagram (an evidence/fact based logic tree) begins with the problem definition/statement (Primary Effect) which needs to be very specific describing the what (Low DO), where/location (Basin 1 and 2 hypolimnion), when/time (Warmer months – Summer), and Significance (EPA 303 Impaired Body of Water). Once the problem is defined, the investigators begin asking “Why or Caused by” which leads to logic based development of a divergent (branched) series of causes and effects depicted as a chart/diagram. Investigators keep asking why or caused by until a sufficient number of causes and effects have been determined (minimum of 5 Whys). Each Cause/Effect is supported with fact based, sensed evidence. Causes can be condition causes (occur over an extended period of time) or action causes (over a shorter period of time).

Problems occur when action and condition causes line up at the same time and in the same place/space.  Effective solutions address the majority of causes and prevent, change, mitigate the primary effect/problem from recurring.

The most effective solution(s) address(es) the action causes.

The Low DO Cause and Effect Diagram shows major causes of Warmer Water Temperature, Thermal Stratification, Carbon Biochemical Oxygen Demand (CBOD), Nitrification BOD (NBOD), Sediment Oxygen Demand (SOD), and Chemical Oxygen Demand (COD- i.e., metals oxidation).

Figure 1 depicts a Simplified and Condensed Cause and Effect Chart/Diagram which shows the major causes for Low O2/DO in Basins 1 and 2. Both Basins 1 and 2 represent 4% of the total volume of water in Lake Whatcom.

Cause/Effects are depicted in each “white box”. Blue arrows point down and depict answers to “why or caused by”, Potential Solutions are depicted in “blue boxes”. Red arrows from the solutions box are drawn pointing to the cause or causes which they address.

Algae, caused primarily by phosphorus (P), and nitrogen (N) nutrient salts assimilation and digestion contribute to the CBOD by consuming DO/O2 via respiration at night and via aerobic (O2) bacterial/microbe decomposition when they die. However, algae DO NOT represent all of the CBOD in Lake Whatcom. Other CBOD sources: organic matter (CBOD) in Basins 1 and 2 are sediments caused by androgenic (man) and natural sources transported into the lake by streams, creeks, rivers, storm-water run-off, landslides, precipitation, air, or prior historical lake usage (saw mill debris/saw dust, sunken logs, coal mine debris/fines, decomposing train trestle wooden structures and iron rails, remnants of boats which burned and sank in the lake, etc.), also consume/deplete DO via aerobic bacteria / microbe – decomposition / decay / digestion processes.

(Examples of organic matter: Coal is decomposed, hardened plant (peat) containing carbon (C), hydrogen (H), oxygen (O), Nitrogen (N), ash, and sulfur (S) with minor impurities of chlorine (Cl) and sodium (Na). Logs/wood pulp contain C, O, H, N and small amounts of other elements (calcium (Ca), potassium (K), sodium (Na), magnesium (Mg), iron (Fe), and manganese (Mn). Organic matter is heterogeneous (from many different sources) and very complex. Generally, organic matter is mainly composed of C, O, N, H, and usually contains S, P, and many other elements (Na, K, Mg, Ca, Fe, etc.)

NBOD Nitrogenous Biochemical Oxygen Demand is caused by bacterial/microbial transformation of ammonia (NH3) into nitrite (NO2) and nitrate (NO3) consuming oxygen (O2, dissolved oxygen (DO)) with each step.

SOD Sediment Oxygen Demand caused by aerobic bacterial/microbe decomposition of particulate organic matter in sediment from external sources (leaf litter, particulate BOD, other plant biomass)

COD Chemical Oxygen Demand is inorganic chemical reactions which consume/require O2/DO.

Example: Metals Oxidation (Iron + DO+ H2O -> Iron Oxides (FeO and Fe2O3) “Rust”.

References:

  1. Overview of Root Cause Analysis Techniques R. Bowen 5/18/2011
  2. https://www.epa.gov/caddis
  3. https://www.epa.gov/sites/production/files/2015-12/temp-cd_sim_1500.jpg
  4. https://www.epa.gov/caddis-vol1/caddis-volume-1-stressor-identification-step-2-list-candidate-causes 
  5. Minnesota Pollution Control Agency; Dissolved Oxygen TMDL-Protocols and Submittal Requirements, December 2008

Warm Water Temperature is caused by solar radiation intensity, and longer (hrs.) duration exposure, usually resulting in a decrease in DO solubility, concentration, and availability. 

Stratification is a division of water column into strata, or layers, of water with different properties. These divisions are usually defined by temperature and density.

Thermal stratification is usually seasonal with clear delineations between layers ( upper – epilimnion, middle -metalimnion, bottom- hypolimnion) during the summer. During summer, heat transfer from the sun , caused by conduction, convection, and radiation  facilitate a change in temperature and water density in the middle metalimnion which in turn causes one or more barriers or thermoclines to form. These barriers of temperature and water density prevent 02 exchange between the warmer, less dense, upper epilimnion waters and the colder, more dense hypolimnion water, which in turn,  fixes/defines a finite concentration of DO in hypolimnion and prevents reaeration of the hypolimnion in warmer months (late spring, summer, early fall).

DO solubility, availability, concentration, and thermal stratification are not an issue in colder, winter months due to conduction, convection, mixing, etc., which facilitates the colder water temperatures throughout the Lake.

The major source of O2/DO in Lake Whatcom in winter is atmospheric exchange between air and water, cold temperature, and early spring mixing caused by wind, current, convection/conduction, and turbulence.

Although algae/phytoplankton, and other photosynthetic plants produce O2/DO in the lake, the majority of photosynthetic O2/DO is produced in warmer weather months (late spring/summer/early fall) when biological and other environmental conditions are favored (i.e., increased photosynthetic rates; biological growth/reproductive rates; enzymatic rates; metabolic rates; increased daylight hours, increased light intensities, increased nutrient salt solubility/ionic strength, etc. which are caused by warmer water temperatures.)

Chart 1 shows the relationship of O2 (Oxygen) solubility vs water temperature. Colder water temperature yields higher DO solubility/availability/concentration.

DO water solubility is affected by temperature, pressure, and salinity. Since Lake Whatcom is a fresh water lake, salinity has no impact on DO solubility and can be eliminated. From Bathymetry recordings, Lake Whatcom surface is ~ 310 ft above sea level, and atmospheric pressure has a marginal effect on DO solubility. At sea level atmospheric pressure is 14.7 pounds per square inch. At 300 ft above sea level the atmospheric pressure is ~ 14.54 pounds per square inch, so there is a marginal impact on DO solubility in Lake Whatcom from pressure. Therefore, the most critical condition on DO solubility is water temperature.

Solutions Development: Effective solutions address the majority of causes and prevent, change, mitigate the primary effect/problem from recurring.

Solution 1. Hypolimnion Aeration via pumping Basin 3 Hypolimnion water into Basins 1 and 2 Hypolimnion


Figure 2. Pumping System Proposal for increasing DO in Basins 1 and 2

Pump water from Basin 3 hypolimnion into shallower Basin 1and 2 hypolimnions in summer months, mimicking the effects of cold water temperature in winter months (Figure 2). Basin 3 contains 96% of Water volume in Lake and functions as a “Heat Sink” in the lake. Basin 1 and 2 hypolimnion DO concentration can be improved immediately by engineering a pumping feedback loop system with DO/temp probes inserted into various positions/depths of the Lake. Pump the denser, O2 rich water from the deeper Basin 3 into the bottom/hypolimnion of Basin 1and 2 to levitate/displace the warmer, less dense, O2 depleted Basins 1 and 2 DO depleted water, and pump/manage this water out via Whatcom Creek.

A Hypolimnion Cooling and Aeration system could be engineered to treat/filter cold “snow melt, Dense, O2 enriched water “entering Lake Whatcom Basin 3 from the Nooksack river diversion and treat/filter water exiting Lake Whatcom Basin 1 via Whatcom Creek to also help manage TMDL P into and out of Lake Whatcom.

 

The costs associated with implementing and managing such a pumping system will have to be determined but this solution will solve the Low DO problem removing the EPA 303 impaired body of water classification.

Decreasing water temp in Basin 1and 2 hypolimnion in the Lake in late spring and early summer months via implementing a pumping/ feedback loop system like the one described above will increase DO content immediately, prevent thermal stratification, and allow atmospheric air /water O2 exchange between all layers in Basins 1and 2.

Table 1: Fondriest Environmental, Inc.: Water Temperature.” Fundamentals of Environmental Measurements. 7 Feb. 2014. Web. < http://www.fondriest.com/environmental-measurements/parameters/water-quality/water-temperature/ >.
Low Dissolved Oxygen (DO) comparison: Whatcom County/DOE TMDL Plan vs Clean Flo

Decreasing water temp in late spring and early summer months will also increase gas solubility (O2, CO2, etc.), lower nutrient (salts) solubility, decrease turbidity, decrease biological growth and reproductive rates, decrease metabolic rates, decrease cellular enzymatic rates, decrease photosynthetic rates, and decrease kinetic rates (chemistry/physics rates of reactions) – all observed/sensed and measured in winter/colder water temperature months (see Table1 on Water Temperature Effects on Water Quality).

Solution 2. Install “Clean Flo” Hypolimnion Laminar Flow Aeration System

Laminar Flow Inversion and Oxygenation

The most important part of CLEAN-FLO’s unique water improvement process is called “Continuous Laminar Flow Inversion and Oxygenation”. Laminar flow inversion sets the stage for other functions to take place that lead to eutrophication reversal and water quality improvement. CLEAN-FLO invented and engineered this energy efficient process for a wide range of fresh water and wastewater applications. Unlike ordinary diffused air systems, surface aerators, paddlewheels, hypolimnetic aerators, or propeller-aspirator aerators, Clean Flo process oxygenates an entire body of water from top to bottom.

Figure Clean Flo Diffuser creates tiny air bubbles. Set of diffusers oxygenate an entire body of water.

Laminar flow created by our systems is non-turbulent and will not increase suspended solids or increase turbidity. In fact, the opposite is true, suspended solids and turbidity will be reduced. Our diffusers are placed on the bottom and are not suspended above the sediments, to ensure oxygenation of the sediment-water interface. As the bubbles release from a diffuser, oxygen is transferred to the water from the bubble, and they also move water gently to the surface and across the surface where additional oxygen is absorbed by the water. CLEAN-FLO systems are designed to completely mix the surrounding waters and evenly distribute dissolved oxygen throughout the sediments for efficient microbial utilization.

Continuous laminar flow inversion oxygenates the water and removes toxic gases.

Laminar flow inversion and oxygenation carries oxygenated, toxic gas-free surface water down to the bottom where it initially binds phosphorus and nitrogen to the sediments and then reduce sediment P, and N via biochemical pathways of P, N metabolism in re-establishing the food chain, thus reducing P which the TMDL addresses. This oxygenation helps purge the water of carbon dioxide (CO2), which produces an environment that promotes better water quality. Other gases such as hydrogen sulfide (H2S) and ammonia are also purged from the sediments. Oxygenation enables beneficial microorganisms to feed on bottom non-living organic sediment. It enables aquatic insects to feed on the microorganisms, and fish to inhabit the bottom waters and feed on the insects, providing a valuable natural food source to improve fish growth and health.

CLEAN-FLO laminar flow systems increase inversion of a water body to several times a day or several times a week or month. The amount of inversion depends on CLEAN-FLO’s engineering design to counteract incoming pollutants and pollutants in that particular body of water. Clean Flo systems are designed for a particular site and account for variables such as water depth and volume, basin bathymetry, water flow rates, presence of aquatic weeds and algae growth, and thickness and composition of lake sediment.

Continuous laminar flow aeration and oxygenation has provided valuable improvements in water quality and fish health and growth, while also producing reductions of nutrients, non-living organic muck, and foul odors.

Clean Flo provided upon request, cost estimates of the Clean Flo System and proposed evaluating this proposed solution on a Pilot basis. Attached are the estimates. I propose installing/testing the pilot in Basin 2 first and then decide on forward strategy basis typical water quality results which could be performed by WWU laboratory.

Basin 2 Pilot ($850,000-$1,000,000 first year and $200,000 each year to operate/maintain after installation)

  1. Cost (materials, labor, installation, travel, etc.) $650,000 not including site work, electrical and building to house compressor.
  2. Annual maintenance- electricity, analytical testing costs, augmentation chemicals, nutrient sponge, etc. $150 – 200,000.
  3. Installation timing (time of year; duration) – any time weather permitting – 2-3 weeks
  4. How much time before we began see results/evidence that Clean Flo works in Basin 2? 30-60 days and will continue to improve for up to one year.
  5. Examples of non-eutrophic lake installations – have to do some searching for non-eutrophic applications. Most applications are eutrophic.
  6. Photos/diagrams/testimonies of successful installations – case study attached.  I can also send you a basic presentation on our system and some projects/ photos if you have some way to accept a large file. (I have a copy of slide presentation and can forward upon request).

Basin 1 ($820,000-$1,000,000 first year and $200,000 to operate and maintain each year after installation)

  1. Cost (materials, labor, installation, travel, etc.) $620,000 not including site work, electrical and building to house compressor.
  2. Annual maintenance- electricity, analytical testing costs, augmentation chemicals, nutrient sponge, etc. $150 – 200,000.In addition to the benefits delivered due to inorganic chemistry changes achieved by raising Dissolved Oxygen levels, (reduction in Iron, Manganese, etc.) we deliver interventions to direct the biochemistry and biology in favorable directions by exploiting our biotechnology expertise.Clean Flo’s biotechnology first achieves aerobic conditions throughout the water column by destratification and oxygen restoration. Changing the predominant conditions in the water column (particularly in benthic zones) from anaerobic to aerobic is a primary change of system conditions that enables the biochemical pathways for nutrient metabolism to be directed into sustainably more beneficial outcomes.These biochemical pathways are of two basic kinds:
    • Catabolic – i.e. the breakdown of organic contaminants and nutrients
    • Anabolic – i.e. the uptake of the products of the catabolic breakdown processes into the synthesis of higher-level organisms known as the “Food Chain”.In anaerobic conditions, catabolic processes are slow, so that organic debris builds up as organic sediments. Within these sediments, anaerobic conditions are conducive to the proliferation of anaerobic organisms. This results in the sustenance of organisms such as E. coli, cryptosporidium, and protozoan parasites and pathogens such as Giardia.The breakdown products of anaerobic digestion include toxic substances such as ammonia, hydrogen sulfide, methane, methyl mercury, etc. These substances are nutrients that support a limited “Food Chain” of algae (cyanobacteria), that proliferates opportunistically when conditions favor them (summer) resulting in algae blooms.
    Cyanobacteria have a greater propensity for fixing Nitrogen from ammonia and thus excessive benthic ammonia levels, coupled with stratification are particularly conducive to Cyanobacteria Hazardous Algae Blooms. Aerobic conditions also deliver favorable organoleptic results; by eliminating hydrogen sulfide odor and taste issues are eliminated. Similarly, by eliminating Cyanobacteria the production of Geosmins (earthy taste/odor) are eliminated.

At the biochemical level Clean Flo interventions are architected off two platforms:

  1. Enzymatic Digestion of accumulated organic contaminants along aerobic biochemical pathways to convert these contaminants into food substrate that favors and supports aerobic microorganisms to further expedite their breakdown.
  2. Micronutrient Supplementation to stimulate and promote the establishment of favorable phycological biodiversity that is supportive of an aerobic “Food Chain”. What this means is that at the phycological level (algae, diatoms, cyanobacteria) we create conditions that favor the proliferation of green algae and diatoms so that they will out-compete cyanobacteria. In this way, Clean Flo create the base levels of a positive Food Chain. Diatoms are food for zooplankton, so the proliferation of Diatoms promotes the proliferation of zooplankton and thus establishes the next level in the Food Chain.

For reservoirs focused on the production of potable water the benefits delivered include:

  • Reduction of organoleptic problems (hydrogen sulfide, geosmins, iron, manganese)
  • Reduction of toxic cyanobacteria
  • Reduction of the risk of cyanobacteria producing microcystin and other toxins when they are subject to algaecide treatment in the reservoir or chlorination in purification processing
  • Reduction in total suspended organics (algae, organic detritus etc.)
  • Reduction in chemical costs associated with water treatment – less algae, lower disinfectant usage, lower THM formation (disinfectant by product carcinogens)Reduction in hazardous conditions (HABs, e. coli etc.) that restrict recreational use of the water body.

As the Food Chain is re-established it results in larger healthier fish populations, and even populations of fish predators such as eagles, pelicans etc.

That Clean Flo Biotechnology Solutions are implemented in large-scale fish farming operations is testament to their effectiveness. The benefits delivered include:

  • Reduction of benthic sediment from intensive feeding and defection of large numbers of growing fish.
  • Reduction of the proliferation of protozoan parasites in the benthic sediments.
  • Consequent elimination of periodic outbreaks of parasitic disease in the fish populations.
  • Lower fish mortality.
  • Healthier, faster growing fish.
  • Consistent optimum levels of Dissolved Oxygen.
  • More variety and more natural food and nutrition uptake due to the presence of a dynamic Food Chain.

Clean Flo has 46 years’ experience and success stories for restoring and improving water quality in different lake and reservoir application around the world.


  1. TMDL P solution – Estimated price tag of $100 million dollars and 50-year period to bring DO concentration in Basin 1 and 2 to 2003 levels. Spend $50 million in first 5 years, “$10 million dollars to improve water quality” in Lake. Assumes that main cause for DO depletion in Lake Whatcom is Algae respiration and aerobic bacterial decomposition. That statement is not supported with any evidence developed in Lake Whatcom and is based upon “conventional wisdom” developed from studies based on Eutrophic lakes/water bodies. We have raised concerns that the TMDL P solution will not address all causes of Low DO in Basins 1 and 2 and will not improve hypolimnion DO by itself. Causal Analysis show DO depletion/consumption in Basins 1 and 2 hypolimnion is caused by algae and other organic matter aerobic CBOD causes, NBOD, SOD, COD, as well as water temperature and thermal stratification causes.

Improvement in DO concentration is caused by reaeration of the hypolimnion which occurs in cooler months of the year and is associated with cooler water temperature, improved DO solubility and absence of a thermal barrier which enables O2 atmospheric exchange between the epilimnion and other layers (metalimnion, hypolimnion) of lake further which is caused by conduction, convection, and turbulence/mixing via wind and wave action.

Stabilized concentrations of DO in the hypolimnion will prevent anoxic conditions and associated anaerobic decomposition biochemical and chemical reactions (prevent formation of H2S,NH3,methyl mercury and formation of soluble Phosphate salts).

Proposed Scenario(s) to Implement the Most Cost-Effective Solutions to address Low DO Causes

  1. Implement Clean Flo Pilot in Basin 2 for $850,000 in 2018.
    1. Evaluate Clean Flo claims via analytical testing/result evaluation by WWU and/or independent qualified contract laboratory.
    2. Assess Basin 2 pilot effectiveness/viability within 12 months.
    3. Assess viability: improves DO, reduce Algae, reduce P, N via claimed sediment fixation, reduce CO2 and other toxic gases (H2S, NH3), and reduces anaerobic bacterial processes (i.e., methyl mercury formation, other), reduce drinking water.
  2. Results:
    1. If Pilot Basin 2 is successful, install similar Clean Flo system in in Basin 1.
    2. If Pilot in Basin 2 is unsuccessful validate failures, work with Clean Flo to determine corrective action to assess viability. Evaluate/discuss Bioaugmentation chemistries, Nutrient Sponge Applications, and other biological/microbiological solutions based upon Clean Flo 46 years’ experience to address failed water quality improvements.
  3. Discuss Clean Flo Nutrient Sponge and Bioaugmentation solutions vs TMDL P solutions to determine the most cost-effective solutions. Implement most cost-effective solution or combination of solutions to meet TMDL P regulation requirements.

Determine Sources of E. Coli to Manage/Control TMDL on E. Coli

  1. Utilize/employ DNA Ribo typing to identify E. Coli source(s) (Man, Domesticated Animals/Pets, Wild Animals, Water Fowl, Deer, etc.
  2. Develop and evaluate corrective action solutions based upon cause and effect analysis to reduce, control, eliminate source(s) to prevent transportation into Lake.
  3. Implement the most cost-effective solutions
    1. Footnote: Identification of Fecal Escherichia coliform in Humans and Animals by Ribotyping, C.A. Carson, B. Shear, et al, Applied and Environmental Microbiology, December 2017,Vol 83, Issue 23

Disinfectant by Products Exposure Concerns – Short and Long-term solutions

Although EPA regulates 7-8 disinfectant by product (DBPs) concentrations (trihalomethanes (THMs) and trihaloaceticacids (THAAs) in drinking water, these DBPs produced by chlorination of suspended organic material (Algae, humic/fulvic acids, etc.) present in Lake Whatcom source water have been shown to be carcinogenic in laboratory animals. Citizens and researchers have expressed long-term exposure concerns to the 7-8 regulated DBPs. There are 80 plus additional halogenated DPBs which may also be present in chlorinated drinking water which are not regulated by EPA. Exposure routes are: ingestion (drinking), inhalation (breathing in volatile DBPs while taking hot baths/showers/hot tubs), epidermal (skin exposure via swimming/bathing in chlorinated pools/hot tubs.

Short-term solutions – purchase and install “whole house” granular charcoal filters on main drinking water line into a house so that all faucets, shower heads, etc. are filtered and exposure is eliminated. Use oxygen disinfectant chemistries or equivalent chemistries in pools/spa/hot tubs to prevent/mitigate dermal exposure.

Long-term Solution- COB and LWWSD evaluate cost effective “Oxygen “based Disinfectant Chemistries which do not form carcinogenic THMs, THAAs., and other halogenated DBPs. Supplement or replace current chlorine disinfectants to reduce or mitigate all exposure routes. Implement the most cost-effective solution or combination of solutions.

Low DO Solutions:

We disagree with the statement that Algae is the primary cause of Low O2 in Basin 1 and 2. We question whether the $50 million TMDL P decision, now a law, to be spent in the next 5 years and with a total time projection of 50 years and estimated $100 million price tag (i.e., managing P and eliminate Algae respiration, death, and decomposition) will improve Low DO concentration in hypolimnions. Although managing/minimizing P in Lake Whatcom Watershed (TMDL) will help reduce/eliminate Algae and minimize consumption of some of the Low DO (DO depletion) in Basin 1 and 2 hypolimnion, it will not address all causes of Low DO, nor provide a cost-effective solution to reaerate the hypolimnions.

We believe reaeration of the hypolimnion via proposed solutions 1 or 2 coupled with a more cost effective TMDL management stream and storm water abatement plan is critical to restoring and improving DO concentrations in Basins 1 and 2.

Respectfully,

EJ Ledet and Richard Bauman

Sudden Valley Science Committee (2003-2017)

 

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