1. How does the MWRD generate energy and revenue through its Lockport Powerhouse? The Lockport Powerhouse typically generates approximately 40 million kilowatt hours of electrical energy annually, generating about $1.2 million in revenue each year. That is clean renewable energy created through hydroelectric power. The water flowing through the facility over the Chicago Sanitary and Ship Canal is harnessed by two turbines, and that energy source is sold back to ComEd to create a savings for taxpayers.
  2. Where is the power plant?  The Lockport Powerhouse and Lockport Controlling Works are located near the confluence of the Chicago Sanitary and Ship Canal and the Des Plaines River in Lockport. These facilities enable the MWRD to control the water levels of the canal. The powerhouse marks the southern point of the MWRD-managed Chicago Area Waterway System (CAWS). The MWRD constructed the Lockport Controlling Works in 1899, followed by the Lockport Powerhouse in 1907.  
  3. When the grid goes down, electric utilities from around the country send out teams to help with repair. is there anything similar with water systems? With regard to power, we do not have back up generation. We are priority one and ComEd is very responsive.  We have never had a full plant outage.  Each plant has two feeds from different ComEd substations.  We have lost one line, but not both.

Diversion from Lake Michigan

  1. Does any nontreated water make it to the river and is there a plan to fix it? Yes, sewer overflows do occur in heavy rainfall. The Tunnel and Reservoir Plan (TARP) is designed to reduce sewer overflows. Green infrastructure and water conservation during heavy rains can help reduce the likelihood of sewer overflows. Learn more about TARP.
  2. What is the Chicago River diversion rate currently capped at? The State of Illinois is allowed to divert 3200 cubic feet per second (cfs). The MWRD has an allowance of 305 cubic feet per second (cfs) to draw water from the lake; 270 cfs is for discretionary diversion to maintain water quality in the channels and 35 cfs is for navigation purposes. Note that the amount is allocated to the state, not just our discretionary diversion via the Chicago Area Waterway System controls at the lake. The MWRD used to divert more into the waterway system. We reduced our share and that freed up more for the Chicago Department of Water Management to divert for drinking water. Learn more about how we manage the waterways.
  3. Is there any current discussion about reversing the flow (again) so the discharge goes back into Lake Michigan? No. The Chicago Area Waterway System provides vital drainage and flood mitigation for our region. Since the lake is so close in elevation to the surrounding landscape it would be a challenge to drain to the lake rather than to the Des Plaines River in Lockport, which is significantly lower in elevation. The USACE conducted a study that considered various watershed separation scenarios. You can find the report here: 
  4. When it rains hard for several days in the Spring, who makes the decision to allow the river water to run into Lake Michigan and why does it sometimes take several days to make the decision?  Does it have to do with how full the water reservoirs are at the time?  What effect would it have on the work of the MWRD if the river was reversed again? Levels in the waterway system are maintained by our waterways control staff. We can control water going into the system from the lake and out of the system via Lockport. We cannot control other inputs to the system, such as tributary streams (North Branch of the Chicago River upstream of us), flow from our water reclamation plants, surface runoff, and sewer overflows. Those inputs all tend to increase in heavy rains. Under normal conditions the lake level is well above the river (with high lake levels these days, it's about a 5 foot difference downtown). So the Lake wants to flow "downhill" into the river normally. If heavy rains are forecast, we draw the system down by increasing the flow out the downstream end and decreasing any flow coming in from the lake. (Water enters the system from the lake seasonally to improve water quality.) This makes extra room for rain water. If you pay close attention you might be able to see this sometimes: the water level a little bit below normal. We can't lower it too much, though. As a navigable waterway we need to keep enough water depth in the system for boats and barges to operate safely. If there's a heavy storm, sometimes more water enters the system than can flow through the channel. This is similar to if you pour lots of water into a funnel quickly and it backs up. When this happens, water levels start to rise. If water levels continue to rise and there's the danger of flooding AND (this is important) if the waterway system is higher than the lake at the control structures, we can open control structures to let water out into the lake. We call this "reversing" but that doesn't really describe what is happening. In these cases the river is actually flowing out on both ends of the system. If the water level in the system is below the lake and we open control structures we'll actually end up adding more water to the river and increasing the danger of flooding. It only will help the situation if water is able to flow "downhill" into the lake. We sometimes get calls from the public to "open the gates" when the river is still well below the lake at the control structures. Doing that would only add more water to the river. Also, note that the level at the control structures is the deciding factor here. It can be possible for the water to be high at other parts of the system but still too low at the control structures. If we opened the gates in these cases we'd just add more water to the system. TARP reservoirs don't fit into the calculation here. Even when full they are below the elevation of the river and can be isolated by gates from the tunnels. The determination is made based on the level of the river itself at the control structures. One final thing, basement backups generally are caused by insufficient flow capacity in sewers that are above the level of the river. In these cases the river level has nothing to do with backups, they are happening up above the river. I just mention this because it's another point of confusion. The US Army Corps of Engineers conducted a study that included some scenarios for re-establishing the watershed divide to prevent the spread of "aquatic nuisance species" via the Chicago Area Waterway System. You can read about it here: The MWRD's position is that in light of our mission to mitigate flooding and protect water quality we are in favor of scenarios that won't increase flooding or hurt water quality. With the unique drainage setup described here, we depend on the waterway system to drain water downhill across the watershed divide to prevent flooding. It is theoretically possible to re establish the watershed divide but it would likely require some huge infrastructure projects to replace the drainage provided by the waterway system. If we just put up a dam in the canal and removed the control structures at the lake, we'd see flooding almost immediately. The river downtown would rise by 5 feet to match the lake level even in dry weather, submerging the riverwalk.

Green Infrastructure

  1. Do you have a downspout disconnection program? Could disconnected downspout contribute to runoffs and nutrient pollution in streams? Are there any programs to help homeowners switch to disconnected downspouts or rain barrels? No, we do not have downspout program but we do have a rain barrel program, which begins by disconnecting downspouts. Disconnecting downspouts to underground pipes that lead to the municipal sewer system is important because you can slow down the stormwater flooding your community or overwhelming your sewers. This is especially important in older neighborhoods with combined sewers where sanitary sewage and stormwater drain into the same pipes. When it rains, stormwater from your roofs and gutters can overwhelm the sewer system and may lead to basement backups, flooding in your community and combined sewage overflowing into nearby rivers and lakes. Disconnecting the downspouts is one of the cheapest and easiest stormwater management projects you can implement at your home. Check out our Green Neighbor Guide for more tips. 
  2. How do we prevent bugs from being attracted to water when we collect it? A rain barrel is a great tool to help you effectively collect rain water. Our rain barrels come with screens. When installed correctly, they will keep bugs out. You can purchase rain barrels on our website. 
  3. Was Green infrastructure considered to assist with stormwater issues? Green infrastructure is a major part of our work. Check out our Green Infrastructure page.

Resource Recovery

  1. Does MWRD compost have any unpleasant odors? Our compost has an earthy or dirt-like odor. 
  2. PFAS? in biosolids? The MWRD and water sector are closely following concerns about per- and polyfluorinated alkylated substances (PFAS) and continuing to rely on the current science in its response. That science shows no significant health risk from human exposure to biosolids and that contamination of surface or ground water from biosolids is very unlikely. We urge federal and state regulators to focus on stopping these chemicals at their source if necessary through appropriate controls on industrial and other uses – before they enter the sewer system or the environment – and to consider the impacts of new policies or laws on utilities. The water sector is committed to understand more about PFAS and supports further research. 
  3. Class A?  The Class A standard is the USEPA’s most stringent criteria for biosolids. The EPA regulations for biosolids include approved treatment processes and establish levels of trace metals and pathogens (Class A standard, which is essentially pathogen-free, and Class B standard which is a lower quality). The MWRD’s Class A biosolids meets the EPA’s Exceptional Quality (EQ) standard, which meets the low-level trace metal limits. We go a step further to make our EQ Compost. Woodchips are used as a bulking agent for composting with biosolids in open windrows. The composting process raises the temperature of the biosolids and wood chip mixture, which kills off pathogens to achieve the USEPA Part 503 regulations for Class A biosolids pathogen reduction.

Stormwater Management

  1. What is the MWRD’s coverage area? The link and a map to municipalities in the MWRD service area can be found here.  Additionally, our website has a great deal of information about our work, so please visit frequently and follow us on social media.
  2. What percent of Chicago’s sewer system is combined and what percent is MS4? We serve a combination of combined and separate sewer systems in municipalities and townships, some of which are completely within the MWRD service area and some that are partially within our service area. Our combined sewer system service area is 375 square miles and our separate sewer service area is 508.5 square miles, so it is a breakdown of approximately 42 percent combined and 58 percent separate. For a complete listing, click here.
  3. Does the MWRD also partner with the Lake County in stormwater management since some watersheds span multiple counties? Correct. Water knows no boundaries. Lake County Stormwater Management Commission been an integral partner in that work. Check out our project at Buffalo Creek which is located in Lake County but also benefits downstream communities in Cook County.
  4. When the material used in the Space to Grow program absorbs water does it get slippery or is it safe for kids to play on? Any surface can be slippery with rain and ice. The nice component of Space to Grow is that the play surfaces are permeable and designed to soak up that water rather than it puddle and become slippery.  In addition to providing community members in low-income neighborhoods with safe outdoor spaces to play and stay active, Space to Grow schoolyards help CPS meet daily recess and physical education requirements for elementary schools. These green schoolyards also provide a daily connection to nature, which research has shown helps reduce stress and improve academic performance. The new landscape features capture a significant amount of rainfall, reduce the load on the combined sewer system, helping keep the city’s water resources clean and resulting in less neighborhood flooding. This provides students and neighbors an education about GI techniques and purpose. Since 2014, the partnership has converted 25 school playgrounds to capture more than 4.4 million gallons of water per rain event. Check out our time-lapse video of our work at Wadsworth Elementary School in the Woodlawn neighborhood.  
  5. How can I contact your green initiative group? Our stormwater management engineers and green infrastructure engineers are hard at work. Check out our Green Infrastructure page and resources. We fund local projects throughout the year, so we are always eager to hear from you to partner on green infrastructure solutions. For inquiries, contact us at with your questions and we will attempt to put you in contact with the proper staff members. 
  6. Isn’t that hill a terminal moraine from the Wisconsin glacier? Over the last 12,000 years the water level of Lake Michigan has dropped three times, and the terminal moraine, or the Valparaiso Moraine, is a little west I believe of that hill and watershed boundary Justin showed. The Des Plaines River, the Chicago Sanitary and Ship Canal, the Cal-Sag Channel, all pass through the moraine. Further east is the Tinley Moraine.

TARP (Tunnel and Reservoir Plan)

  1. How often does TARP get full? McCook Reservoir Stage I (3.5 billion gallons) has reached capacity before but Thornton Composite Reservoir (7.9 billion gallons) has not. McCook has filled a few times since it went online in late 2017, and when that happens there are a variety of factors that may cause it to reach capacity and stay at capacity or near capacity, as additional rainfall and operations at the plant may require more time to draw the water in the reservoir down. 
  2. I toured McCook before it opened, will there be another tour before part 2  goes online? Check back in with us around 2029. Keep in mind Stage I is already in use. 
  3. How much CSO event reduction do you expect when TARP is completed in 2029? The Thornton Composite Reservoir has virtually eliminated CSOs in the Calumet Area. While McCook serves a bigger area, it should make a huge difference (and already is) in mitigating flooding and preventing pollution from entering our waterways. 
  4. Did the MWRD use tunnel boring machines? Yes. We have used a boring machine and have old pictures and video clips should you be interested. We have 110 miles of tunnels. 
  5. I wonder if any interesting fossils have been found during these excavations. There have been a number of fossils and interesting finds while excavating 400-million-year-old dolomite limestone. Some findings are on display at our Mainstream Pumping Station. 
  6. Has there every been a situation where fossils were accidentally blown up? We are unaware of fossils being blown up, but as you can imagine boring through miles of rock 300 feet below ground we have encountered massive amounts of rock and earthwork. A fulfilling part of this work is recycling this material and finding new uses for it. We helped build a new scenic overlook at the Centennial Hill along the Centennial Trail in Willow Springs by removing 1.8 million cubic yards of overburden (dirt) from the neighboring McCook Reservoir. 
  7. Can you add a fossil slide the next time you do this? Thanks for the suggestion. We will look into exploring more ways to incorporate the geologic nature of our excavation work. We have received mining awards with our partners for work at Thornton Reservoir and McCook Reservoir.
  8. Where does funding for TARP come from? TARP is funded through our Capital Improvement Funds as well as federal dollars thanks in large support from the United States Army Corps of Engineers Chicago District and our federal delegation fighting for resources. 
  9. What are the rocks used for? Limestone and other rock collected can be used for construction projects throughout the region. 
  10. Just to clarify, the reservoirs are filled with clean water and the deep tunnel reservoirs are filled with sewage water? The tunnel and reservoirs are filled with the same water from combined sewer systems. While the water is primarily stormwater, the tunnel system captures the “first flush” a term used by the USEPA to describe the highest pollutant loaded combined sewer overflow (CSO). The MWRD estimates the tunnel system captures more than 86 percent of the CSO pollution load in the Mainstream/Des Plaines system and 100 percent of the Calumet system. Because of this, the region has seen tremendous ecological recovery of the waterways during the implementation of TARP. 
  11. Where was the inlet? The McCook Reservoir has an inlet from the Mainstream Tunnel system at the north end of the reservoir and a Des Plaines tunnel at the west side of the reservoir. The Thornton Composite Reservoir has an inlet on its east side from the Calumet tunnel system. Another inlet from the Thorn Creek overbank flooding will also be situated in the southeast corner of the reservoir that is currently directed to the Thornton Transitional Reservoir. 
  12. Has the McCook Reservoir ever overflowed? No. We will close the gates to the reservoir to prevent the flow from reaching the reservoir should it threaten to overflow
  13. Are there other cities with these types of big tunnels? London, Singapore, Seattle, Portland, Vienna, Melbourne and Milwaukee have all emulated similar systems to our TARP and "Deep Tunnel".
  14. Were there any fossils discovered during excavation of the tunnels? Yes, there are many fossils. In fact we have a Cephalpod Orthocone displayed at a Deep Tunnel pumphouse.  It is approximately 2' long and basically looks like a squid poling out of a ice cream cone.
  15. Was the limestone used for construction or for any Chicago building facades? The limestone was used for the production of concrete and road bed material.  Some limestone in the Lemont area was used for building facades.
  16. Is limestone an advantage for building/holding water? Limestone does secure the reservoir, but we also rely on a layer of shale at the bottom of the reservoir which is impervious. We also inject grout around the perimeter of the reservoirs.

Wastewater Treatment Process

  1. How long does it take to complete one wastewater cycle? The entire process from the time wastewater reaches the treatment plant to the time it is cleaned and "reclaimed" takes less than 12 hours. 
  2. Where do the plastics go? Plastics and trash removed from the water are disposed of as garbage and landfilled.
  3. Do you treat wastewater and storm water? Yes! Some parts of our service area do have separate sewer systems that send only sanitary sewage to our water reclamation plants. Learn more about our water reclamation plants.
  4. Is there information on molecular pollutants like hormones (e.g., birth control) and medications (e.g., antidepressants) and how they treated or removed before water is released? Pharmaceutical compounds and their biological degradation products (metabolites) are found in ultra-low concentrations (nanograms per liter or micrograms per liter) in water discharged from wastewater treatment plants (WRPs), according to several research studies carried out all over the world. Wastewater treatment plants are not specifically designed for pharmaceutical removal. In order to eliminate pharmaceutical compounds, current wastewater treatment processes would have to be upgraded with energy and resource intensive technologies such as membrane bioreactors, advanced oxidation processes and activated carbon adsorption. Further research in this field is required to assess the risks associated with the presence of ultra-low concentrations of pharmaceutical compounds in water treated and released from our WRPs. The MWRD encourages safe and proper drug disposal. The MWRD provides drug collection receptacles at three MWRD water reclamation plants and the MWRD headquarters downtown.
  5. What type of biological treatment does the Stickney WRP have? Primary treatment has removed most of the suspended solids from the water at Stickney through filtering and physical means. There is still some remaining, though, because filtration is not practical at the volumes we deal with, and filtering won’t remove dissolved solids. That is when this pivotal biological phase of treatment begins. Here in secondary treatment, a community of microorganisms help remove organic material from the wastewater. These naturally occurring harmless microbes like to eat these solids and need oxygen to thrive, so air is pumped through the water. With lots of food around and plenty of air, the good microbes start to reproduce. Harmful microbes in sewage are generally anaerobic, meaning the air in the tanks is toxic to them. So, the numbers of the good bacteria increase, and any harmful bacteria die off. With no more food and no more air coming in, the good bacteria go into a dormant state. It forms into clumps and sinks to the bottom of the tank. Next, the water enters the final settling tanks where remaining solids settle to the bottom and clean water flows out the top. Read all about the Stickney Water Reclamation Plant.
  6. At the Stickney WRP, how deep are the final sedimentation tanks at the periphery? They are 15' at the side wall and 23' in the center. Each tank can handle 15 million gallons per day. Multiply that by 96 tanks and you get 1440 mgd.
  7. Can you show how MWRD handles food waste liquid sludge waste from a industrial food process company? Liquid food waste generally comes to us via the sewer system, mixed in with the rest of the incoming water. We recover the additional cost of treating water from commercial and industrial dischargers. We also receive high strength liquid waste (HSLW), high strength organic material (HSOM) and other liquid recovered resources directly at our plants. The HSLW and HSOM resources improve and stabilize the MWRD’s biological phosphorus (Bio-P) removal process during wastewater treatment. The sugary and starch liquid wastes provide readily biodegradable carbon that serves as food for the phosphate accumulating organisms that work under anaerobic and aerobic conditions in the MWRD’s wastewater treatment process. These organisms work to remove organic material from wastewater and to recover more phosphorus than normal microorganisms. By removing phosphorus, the Bio-P process ensures cleaner water downstream after the water is treated and released back into the environment. The Bio-P program, a permit only program, brings in millions of gallons of carbon-rich material each year, ranging from spent yeast from local breweries to waste recovered from portable restrooms. The material is then safely disposed of locally to reduce hauling distances and further protect the environment. Since launching the Bio-P program in 2017, the MWRD has already received more than 10 million gallons of HSOM at its Calumet and Stickney WRPs, providing Cook County taxpayers with a revenue stream of greater than $500,000. Read more about it.
  8. With the current effluents very high in India sewerage, is Tertiary Treatment Reverse Osmosis a good option for sewerage treatment and reuse for industry? In Chicago, we are incredibly fortunate to live by the Great Lakes, which contain 20 percent of the world's surface fresh water and 90 percent of North America's surface fresh water, so our history in protecting this source of drinking water and reversing the flow of the Chicago River is all the more important. Tertiary Treatment Reverse Osmosis (TTRO) therefore has never been something we have considered, and thus we might not be the best source to evaluate this option. This technology does provide a new way to look at effluent reuse, and depending on your alternatives, it is best to consider where applicable and affordable. We have been closely analyzing ways to produce water for pipeline reuse for industrial purposes, not for drinking water. In addition to being harnessed, water itself is also reused directly throughout the MWRD treatment process. Every day, more than 15 million gallons are reused in pipeline flushing, blower motor cooling, post-centrifuge centrate flushing and tank cleaning directly at our facilities. 
  9. Do you have separate intakes for normal sewerage and industrial sewerage? Industrial sewage comes to our plants through the same sewer systems as domestic sewage.  
  10. How do you remove heavy metals and pesticides? Heavy metals are regulated and are part of the pretreatment program. We don’t remove them – we prevent them from entering the plants in the first place. Heavy metals tend to settle out in the solids removed in treatment. Our biosolids are carefully monitored for metals. Concentration of metals found in our biosolids from the treatment process are reported here. Thanks to our monitoring and enforcement work upstream, metals concentrations in our biosolids are very low.  Pesticides are classified by USEPA as Priority Pollutants and we generally have a blanket prohibition from their discharge both to the collection system and surface waters under our jurisdiction, due to their toxicity and endocrine disrupting potential. We have only two significant industrial users out of 334 currently regulated under the Pesticide Chemicals Point Source Category, so it is not a major pretreatment concern for us. 
  11. Is the Revolving Algae Biofilm reactor an advanced version of a Rotating Biological Contactor reactor? The revolving algae biofilm (RAB) system is similar to a rotating biological contactor reactor. The technology was actually developed by our partners at an Iowa State University affiliate startup known as Gross-Wen Technologies (GWT) for agricultural applications. But our scientists discovered it could be adapted for algae-based treatment of municipal wastewater at the MWRD’s Terrence J. O’Brien Water Reclamation Plant greenhouse. The RAB system removes phosphorus, nitrogen, and other nutrients from wastewater, while producing algae biomass from waste nutrients and carbon dioxide captured from the air. The algae could remove at least 50 percent of phosphorus from wastewater and can be harvested and commoditized for production of bioplastics, biochemicals, biofuels, pharmaceuticals and dyes; or used as fertilizer or as aquaculture feed.   
  12. What are technologies mostly used for wastewater treatment at the MWRD? Our water reclamation plants use primary treatment and activated sludge secondary treatment processes. The plants required to disinfect effluent use either chlorination/dechlorination or UV disinfection. 
  13. To what standards do you treat the wastewater, ex: BOD/DO  after treatment in wastewater? Our treatment plants meet the stringent policies and parameters presented in the National Pollutant Discharge Elimination System (NPDES) permit program. You can also learn about our NPDES permit for our Stickney Water Reclamation Plant , how the MWRD fulfills federal requirements, and our analysis of the waterways, which includes our continuous dissolved oxygen measurements and other data.
  14. Can you explain how the leftover secondary sludge or treated sludge is handledThe solids from our treatment process are used to produce biosolids, a soil amendment used throughout our region for agriculture and landscaping.  Our solids are taken to temperature-controlled digesters where microorganisms break down organics similar to composting. After digestion, they pass through centrifuges, where it is spun like a washing machine to dewater the solids. The biosolids are then aged and air-dried. Resulting biosolids are mixed with woodchips to produce our EQ Compost. EQ Compost works as a soil amendment to improve soil structure, supply organic matter and allow plants to more effectively utilize nutrients and soil to retain more water. EQ Compost can be blended with topsoil and potting soil for establishing plants or used as a mulch around already establish plants. The MWRD has been producing and providing biosolids to area parks, golf courses and fields for decades. By using this sustainable product here in Cook County where it is made, the MWRD can protect the environment by reducing hauling and landfill costs while improving soil conditions in the process. 
  15. What are the treatment costs and method to collect treatment cost from users? You can read about our User Charge Ordinance and pretreatment requirement charges. We charge based on volume of water, suspended solids, and BOD. Per the Clean Water Act we are required to recover the cost of treating water from industrial, commercial and tax-exempt users. We bill these users to collect the costs.
  16.  Why does the water need to be aerated? The MWRD’s Sidestream Elevated Pool Aeration (SEPA) stations add up to 25 tons of oxygen to the waterways each day by pumping up to 1.3 billion gallons of water per day. Aeration is necessary due to the unnatural form of the waterway. The bottom and banks of the man-made portions of the CAWS are smooth and the current is slow lacking enough turbulence to aerate the water. In addition to the 5 SEPA stations along the Calumet River and Cal Sag Channel, there are two in stream aeration stations along the North Branch of the Chicago River, one at Devon Avenue and one at Webster Avenue which do use air rather than waterfalls and screw pumps. For aeration, can air pumps be used? Air pumps could be used, but are much more expensive. Water dropping over stepped platforms (to aerate) is much more efficient. When the upstream water meets the station, it passes through coarse bar screens inclined on 20-degree angles before drifting into the pumping process. All stations rely on large spiral screw pumps, except for the SEPA 1, which uses vertical propeller pumps. The screw pumps, several feet in diameter, spiral the water up a 30-degree incline, elevating the water as high as 17 feet. All stations, except for the smaller SEPA 2, will pump water at least 400 cubic feet per second (cfs) with SEPA 5 pumping as high as 576 cfs. The aeration during the pumping process is so strong that it in fact generates more oxygen than the waterfalls. The circular screw pumps upward rotation turns the water into something more resembling white water ascending from a rapid. Each of the screw pumps at SEPA stations 3, 4 and 5 can pump more than 50,000 gallons of water per minute, while the smaller SEPA 2 will pump 19,300 gallons per minute.  
  17. How do you move a large quantity of water through the primary tanks while keeping them still? After water flows into primary settling tanks, a revolving conveyor with slats skims off the floating fats and oils while solids settle to bottom.  The slats push the solids to a drain that takes it to the solids treatment process while the floating fats and oils are moved to a drain and then to a landfill. The water might look still but it keeps flowing.  
  18. Which treatment plants have tertiary treatment? We perform tertiary treatment at our O'Brien Water Reclamation Plant (WRP) in Skokie, Calumet WRP on the far South Side, Chicago, Kirie WRP in Des Plaines, Egan WRP in Schaumburg and Hanover Park WRP in Hanover Park. 
  19. Do you specifically seed the tanks with those aerobic bacteria, are they just present, or do they settle from the external environment? Do you seed the tanks with the aerobic bacteria, or are they naturally there? We do not have to seed the tanks with microorganisms except on rare occasions when there are problems with the microbe populations. That is the importance of maintaining a healthy population of microorganisms and keeping a close eye on what is flowing into the plant. 
  20. How long does it take a gallon of water to go through the entire process?  It depends on the proximity of the water to the water reclamation plant, but the entire process from the time wastewater reaches the treatment plant to the time it is cleaned and "reclaimed" takes usually eight to 12 hours. 
  21. Do you have sensors that keep track of large or unexpected amounts of items on the screens, or do you have operators watching a remote video? We have to rake the screens periodically to keep the process moving, so our operators pay close attention themselves. 
  22. Doesn't the rain and wind and snow affect the tank calmness? Yes, but these elements do not interrupt the treatment process. 
  23. Is the plant monitored 24/7? Yes.  All treatment plants (and waterways) are monitored 24/7/365.
  24. Is there a map that has the locations of the rec plants throughout the state?  We are not familiar with a state-wide map of water reclamation plants, but you can learn more about our WRPs and where these important facilities are located and the areas that each serves on our website
  25. Are you able to test for amounts of coronavirus and if so can you draw conclusions on infection rate trends during the pandemic?  I’ve read that other large cities are using their water and sewage treatment plants to identify Covid-19 before symptoms appear and testing increases. Is this being done in Chicago area? I also heard that the city and MWRD need to communicate better for this to work here. Currently, the MWRD is supporting three studies on sewage surveillance monitoring of the SARS-CoV-2 virus for tracking the spread of COVID-19 in the Chicago area through our Monitoring and Research Department. The first study in which the MWRD has participated since March 2020 is a project funded by the National Science Foundation (NSF). A team of researchers from Stanford University and University of Michigan was charged to develop methodologies for detecting genetic markers of the COVID-19 virus in sewage resulting from feces shedding from symptomatic and asymptomatic patients at a community scale and using the data generated to predict the prevalence of COVID-19 in the community. The MWRD’s primary responsibilities on this collaboration are (1) sample collection, preserving (freezing) and shipping to Stanford University, and (2) providing metadata associated with the samples and sewershed information about the MWRD’s water reclamation plants (WRPs). The second study that the MWRD is supporting is a project led by a team of researchers from Argonne National Laboratory (Argonne), Northwestern University (NU), and the University of Illinois, Chicago (UIC). The work in this project will be carried out in two phases. In Phase I, which is already underway, a plan is to be developed for sampling and testing procedures and logistics among collaborators. Phase II entails implementation of the plan. The main role of the MWRD is to provide samples and information about the MWRD’s water reclamation plants (WRPs) and collection systems. The MWRD provides raw sewage and final effluent samples from the Calumet, Stickney, and O’Brien WRPs. Additionally, the MWRD provided stored frozen samples collected for the NSF study from April through September 2020 to UIC. The Argonne/UIC/NU team is responsible for analyzing samples, evaluating the data and communicating the data to the local Departments of Public Health. In December, the MWRD was approved to participate in a national sewage surveillance study with the U.S. Department of Health & Human Services (HHS). The MWRD's WRPs were selected among approximately 100 treatment plants, representing 10 percent of the nation's population. In the first phase of the study, five of the MWRD's WRPs provided samples, analysis and analytical data. For the second phase of the study, all seven of the the MWRD's WRPs were accepted to participate among 320 wastewater treatment plants nationwide covering about 30 percent of the U.S. population. The MWRD also communicates regularly with organizations such as the National Association of Clean Water Agencies who are speaking with the HHS, the Center for Disease Control, as well as the USEPA as to the best approach for a national level sampling and testing program.  As this pandemic continues to progress and these conversations continue, the MWRD stands ready to assist these agencies to gain a better understanding of the spread of COVID-19. To learn more about the MWRD’s response to COVID-19 and the MWRD's work to treat wastewater and manage stormwater during the global pandemic, please click here
  26. To follow-up on tertiary treatment, is there a reason that the Stickney plant doesn’t need tertiary treatment? Tertiary treatment is not required under our permit at Stickney. The IEPA conducted a thorough use attainability analysis of the Chicago Area Waterway System and determined that the Chicago Sanitary and Ship Canal, where the Stickney WRP discharges, was not designated as primary contact and therefore, disinfection at the Stickney WRP is not necessary. 
  27. Do you add alum to increase floccability as they do in primary water treatment? No, we do not use alum, just all natural bacteria! 
  28. What months of the year do you have to use UV disinfection? Our permits require disinfection during the recreational season, March-November. 
  29. Do you have a centralized solids handling facility? We have two centralized solids handling locations at our Harlem Avenue (7430 Portage Trail, Forest Park) Solids Management Area (HASMA) and the Calumet Solids Management Area (CALSMA, 12600 S. Doty Ave., Chicago).  
  30. Are there are plans to roll out UV disinfection to other plants? Not currently. We use a chlorination-dechlorination and sand filtration at other facilities. 
  31. Is there a chlorine residual requirements at the discharge? We are required to monitor for any chlorine residuals at discharge, with a daily limit of 0.05 milligrams per liter. We sample daily during the chlorination process from March to November and report any chlorine residuals on our discharge monthly reporting forms to the IEPA. 
  32. Is the North Branch water disinfected? The water discharged from our O’Brien WRP into the North Shore Channel, which flows into the North Branch of the Chicago River, is disinfected. The river water itself is not disinfected.  
  33. Is there a reason the Calumet uses chlorination versus the UV disinfection? Differences in existing infrastructure and hydraulics at the two plants required that a combination of methods be implemented as the basis of final design and construction of the facilities. As recent as 2011, the CAWS had secondary classification for water quality standards, meaning direct contact with water was not possible outside of boating. But in advance of a possible decision by the U.S. Environmental Protection Agency to one day re-classify the CAWS for allowing primary contact, the MWRD Board of Commissioners adopted a policy to disinfect on June 7, 2011. MWRD officials instituted a blue-ribbon panel to evaluate available disinfection technologies and devoted eight months to research and testing to determine optimal solutions for disinfecting at the most economical cost. Using a triple bottom line approach that considers economic, environmental and social criteria, the MWRD evaluated available disinfection technologies and recommended the optimal technology for disinfecting the O’Brien and Calumet Water Reclamation Plant water. An internal task force, which included staff from the departments of Monitoring and Research, Engineering, and Maintenance and Operations, systematically evaluated all available disinfection technologies and reviewed academic research and industry practice literature. The task force also performed bench scale studies, monitored existing plant effluent, reviewed site conditions, and contacted industry experts, manufacturers and suppliers, and other large wastewater treatment agencies. In addition, the task force gathered data about design parameters, operational needs, maintenance requirements, and annual and capital costs. The task force also worked swiftly to ensure disinfection will come online at the same time as the Thornton Reservoir to maximize the water quality impact for the Cal-Sag channel. The task force reviewed combinations of technologies to treat baseline and peak flows to maximize our use of resources and as a result, we were able to do what is needed for less than half the cost of the original estimate, providing excellent customer service at the least cost. Using an existing chlorine contact chamber retrofitted for more efficient contact, the disinfection technologies at Calumet neutralize or kill bacteria and microorganisms in treated water. Engineers modified the existing chlorine contact basin by replacing all interior baffle walls and associated walkways; replacing weir gates, discharge gates, drain sluice gates, inlet sluice gates and a bypass sluice gate; replacing liquid sodium hypochlorite diffuser piping; installing liquid sodium bisulfite diffuser piping; and installing sampling pumps. The UV disinfection system at the O’Brien Water Reclamation Plant accomplishes disinfection as well but in a different way. It is the largest wastewater treatment UV installation in the world, having the potential to treat 450 million gallons of water per day (mgd), using 896 lamps that provide a low pressure, high output performance. 
  34. So biotechnology (using microbes) is a major part of the treatment process? Yes. Our treatment process weighs heavily on a carefully maintained population of microorganisms which work to break down the remaining suspended solids and help them settle in the final setting tank. 
  35. How much power/influence does MWRD have when it comes to laws that regulate companies and the pollution they discard into the water? The MWRD keeps close watch on our water environment through various measures. The MWRD adopted the Sewage and Waste Control Ordinance in 1969, and has since amended it as recently as 2015. The ordinance protects the public health and safety by abating and preventing pollution through the regulation and control of the quantity and quality of sewage, industrial wastes and other wastes discharged into the sewage systems, MWRD water reclamation plants and waters under the jurisdiction of the MWRD. In 1979, the MWRD Board of Commissioners adopted the User Charge Ordinance. The ordinance established an orderly and fair system so that the operations, maintenance, and replacement costs incurred by the MWRD in treating and disposing of the sewage, industrial wastes and other wastes generated by each user is charged for their use of the sewage collection and treatment facilities of the MWRD in compliance with federal regulations. Administering the Pretreatment and User Charge Programs, the MWRD’s Monitoring & Research Department works diligently to protect the quality of the water environment and also generates an important revenue stream from large commercial/industrial users and tax exempt users of the sewage system and the costs of administering the MWRD’s Pretreatment and User Charge Programs. Our Industrial Waste Division (IWD) Field Surveillance section works day and night to protect the public’s health and the water environment by reporting to the scene of chemical spills, fires and other emergencies to ensure our drains and water environment are protected as well. The MWRD adopted the Environmental Remediation Wastewater Ordinance in 1995 and amended it again in 1996 and 2010. This ordinance abates and prevents pollution by regulating and controlling the quantity and quality of environmental remediation wastewaters admitted to or discharged in the sewers systems under the MWRD’s jurisdiction. The MWRD’s Watershed Management Ordinance, which went into effect in 2014 and was amended in 2020, regulates sewer construction within MWRD’s service area and development within suburban Cook County. It provides uniform stormwater management regulations to prevent future commercial, municipal, and residential development and redevelopment projects from exacerbating flooding and protects environmentally sensitive areas.  
  36. What are the tall poles? The poles are connected to solar power aerators that float to the surface of the water to help aerate stagnant water in the reservoirs, alleviating any odors that may emanate from the collected water. 
  37. Do the treatment plants need any upgrade to accommodate the volume when TARP is completed? We are constantly monitoring our systems to accommodate new TARP collections systems. These TARP upgrades unfortunately come with a need for new infrastructure and more energy usage to convey all this water. That means monitoring and upgrading pumps and blowers and additional piping. Fortunately, we are finding new clean energy sources supplying our power to help utilize these systems and relying on internal systems at our water reclamation plants that promote renewable energy sources, such as biogas, and innovative resources, such as new tank and collection facilities and LED lighting, to minimize energy demands. 
  38. If the water level covers the inlet or goes higher - isn't there risk of back flow? The force of the water is great enough to withstand backflow, and if the tunnel is filled, the water by gravity will continue to fill the reservoir. Think of it much like filling a bathtub. If there is backflow, the tunnels are no longer at capacity and the water reclamation plants have room to start treating wastewater again. 
  39. How are chemicals removed from the sewage? Is there information on molecular pollutants like hormones (e.g., birth control) and medications (e.g., antidepressants) and how they treated or removed before water is released?  Pharmaceutical compounds and their biological degradation products (metabolites) are found in ultra-low concentrations (nanograms per liter or micrograms per liter) in water discharged from wastewater treatment plants (WRPs), according to several research studies carried out all over the world. Wastewater treatment plants are not specifically designed for pharmaceutical removal. In order to eliminate pharmaceutical compounds, current wastewater treatment processes would have to be upgraded with energy and resource intensive technologies such as membrane bioreactors, advanced oxidation processes and activated carbon adsorption. Further research in this field is required to assess the risks associated with the presence of ultra-low concentrations of pharmaceutical compounds in water treated and released from our WRPs.  The MWRD encourages safe and proper drug disposal. The MWRD provides drug collection receptacles at three MWRD water reclamation plants and the MWRD headquarters downtown.
  40. Do MWRD's water reclamation plants have a spike in increase during half-time of the Superbowl? In general, our collection system is so large that we don't see any changes in flow during half-time of the Super Bowl. Here is an interesting article on the topic:
  41. Is the treatment process in the open air tanks affected by cold or lots of snow? The water typically never goes below 50 degrees. So we don't have problems with ice freezing on the tanks.  Back in 2013 we had a polar vortex and 93% lake Michigan was cover with ice.  The flow into the plant was 44 degrees for 2 weeks.  That posed a challenge because the microbes become very slow moving and reproduces at half the typical rate. The snow is however a challenge when there is so much. The snow makes it difficult to get to equipment and access points throughout the plants. Plant staff have to collect samples and need access to the sample points and then have to get the samples to the labs.
  42. I understand there is a slurry line that goes to Stickney from the Skokie treatment plant. Is that the "final product" and do all of the other treatment plants similarly send it to Stickney? There is a 17 mile sludge line from Skokie to Stickney.  It is that plants final sludge product which is anaerobically treated at Stickney.  They pump about 2.4 million gallons per day.  The Kirie Plant pumps their sludge to the Egan plant.  The Egan plant treats those solids, however they do have the option to send the Kirie and Egan solids to the Skokie plant.  But this is rarely used.
  43. How much polluted water does the MWRD receive during the wastewater treatment process? About 500 billion gallons of wastewater is treated by our seven facilities every year. The MWRD's total wastewater treatment capacity is over 2 billion gallons per day. To learn specific information about each of our plants, please see our fact sheets by clicking on the links below.

    Water Quality

    1. What has been the MWRD’s role in Chicago river cleanup to support the kayakers? TARP and improved technologies like disinfection at our water reclamation plants have improved our waterways to a quality not imagined 100 years ago. Thanks to this work and demand for clean water, as a result, we are seeing more and more fish species and kayakers and recreation on the Chicago River and Chicago Area Waterway System, leading to new economic development opportunities, activity and growth around our rivers.  We have also made access to these waterways a priority by leasing large parcels of land along waterways to local park districts for a nominal fee. We are also collaborating with our partners to improve riverfront trails, restore riverbanks and remove dams.  Additionally, our debris boats and skimmer boats remove debris that could present a hazard to boaters. 
    2. Drinking Water – Who handles drinking water? The Department of Water Management delivers nearly 1 billion gallons of drinking water to residents of Chicago and 125 suburbs daily. We encourage you to visit their website to learn more about their services or email For more information, be sure to check with your local municipality. 
    3. What are some standards that are being tested? like fecal coliform? PCB? We test and study both water coming into the treatment plants (influent) and clean water leaving the plants (effluent) among other water quality analysis. We test for hundreds of water quality metrics, standards, elements and organic compounds, ranging from fecal coliform to PCBs. To view the data, visit Reports and click on Monitoring and Research. We also closely assess the biosolids we produce. EQ Biosolids meet the USEPA’s 40 CFR Part 503 requirements for exceptional quality (EQ), which are based on comprehensive risk assessments that are protective of human health and the environment. Check out our Biosolids page and read more from our safety data sheet.
    4. Is the Chicago River meeting EPA’s swimmable standard now? The investments the MWRD has made in protecting the CAWS has yielded positive results, cleaner water and a surge in recreational activity and economic development, and today we comply with direct contact for EPA standards, along many parts of the CAWS. Water quality improvements have proven to be essential factors for nurturing aquatic life, while TARP has also helped reduce the amount of combined sewer overflows (CSO), leading to less polluted water and healthier homes for freshwater fish living in the CAWS. In addition to TARP and other measures to improve water quality, we’ve introduced side stream elevated pool aeration (SEPA) stations and other instream aeration stations to help inject needed oxygen into the CAWS and implemented chlorination/dechlorination technologies to disinfect water at our Calumet Water Reclamation Plant (WRP), and UV disinfection at our O’Brien WRP. However, like other bodies of water, the CAWS contains wildlife and bacteria. Anyone considering swimming in the CAWS should consult with their physician. Although water quality is improved, many hazards exist on the CAWS, due to boat traffic, currents, temperature and lack of ingress and egress to name a few. In short, the CAWS is not designed for swimming. 
    5. Are the fish edible? The MWRD encourages fishermen to enjoy recreating on the CAWS while following the local IDNR advisories for fish consumption found here. To learn more about fishing in Illinois, visit
    6. Does the MWRD maintain the Asian Carp electric fence? No. The electric barriers are operated by the U.S. Army Corps of Engineers, which partners with the U.S. Coast Guard and the Asian Carp Regional Coordinating Committee. 
    7. Does electrofishing hurt the fish? Electrofishing stuns the fish for a brief time, but the fish are not harmed. Electrofishing is one of the commonly used tools that MWRD biologists employ to collect fish data, such as abundance, composition, and diversity. In boat electrofishing, the boat’s hull acts as a cathode, while the anodes are on the electrofishing booms which project from the front of the boat, releasing direct current electricity between the submerged cathode and anode. After the current goes into the water, the fish are briefly stunned, affecting their swimming, and MWRD staff collects them in nets and places them in a tank on the boat. They weigh, measure, and inspect fish for disease and other anomalies before releasing the fish back unharmed into the water. 
    8. Is the MWRD the agency which works to prevent incursion of the Asian Carp? The MWRD is a partner agency on the Asian Carp Regional Coordinating Committee (ACRCC), which was formally established in early 2010 and represents the collective efforts of international, federal, state and municipal agencies to combat the spread of Asian carp into the Great Lakes. The ACRCC provides oversight and coordination of interagency prevention activities through development and implementation of an annual Asian Carp Action Plan and complementary Monitoring and Response Plan. For more information, visit The U.S. Army Corps of Engineers have also been a valuable leader in these efforts. Check out the Corps’ Aquatic Nuisance Species Portal.
    9.  Have you caught any Asian carp? We have not caught any Asian carp, but the U.S. Fish and Wildlife Service confirmed an unusually high number of positive Asian carp environmental DNA (eDNA) samples in the South Fork of the South Branch of the Chicago River, also known as Bubbly Creek, in the fall of 2019. The samples were collected downstream of the MWRD’s Racine Avenue Pump Station around the time of a pumping event due to a storm. This triggered two weeks of intensive monitoring in the Bubbly Creek area completed by the MWRD, Illinois Department of Natural Resources and Asian Carp Regional Coordinating Committee partners using traditional fish and water sampling. During that time biologists found no evidence of Asian carp in the area. We did however catch one of the largest common carps we have ever come across in July 2019 in the Little Calumet River. This species does not pose a threat. Read about it here
    10. What are any planned improvements or projects planned to help the environment? Everything the MWRD does has an eye on the environment. In fact, we were created 81 years prior to the US EPA’s creation. Whether that was the reversal of the Chicago River, implementation of wastewater treatment, TARP or today’s resource recovery program and stormwater management projects to mitigate flooding, all of these initiatives share in a goal to protect our water environment. Check out our website to learn more about our exciting work.

    Work at MWRD

    1. How do I learn about careers in wastewater? If you are interested in learning more about career opportunities at the MWRD, please click here for more information. To schedule a student presentation with a STEM professional to discuss their career in water, please email We also have K-12 student resources available online. 
    2. What kind of certification do you need to be able to work for the MWRD? Do we need PE licenses to work at MWRD? There are various employment opportunities at the MWRD with varying requirements, depending on the position. Many positions require civil service examinations. For more information, visit Careers. 
    3. What percentage of MWRD employees are union tradespeople? We have 780 trades persons on staff. With about 1,900 staff members, we have about 41 percent represented employees. 

    Tour Information

    1. Are these lectures/tours posted for others to be able to view that were unable to join at this time?  We offer virtual tours about once per month but you can also request speakers to join your class and tailor it to your needs.  Please email  to request a speaker for a virtual presentation or event. Learn more here.
    2. Will this be recorded? And/or could slides be made available? These visuals are very illuminating. Are you planning to post this presentation somewhere? It has lots of great visualizations. Yes! Please click here for a one hour recorded tour. We are also currently participating in virtual presentations and events. Please email to request a speaker for a virtual presentation or event. Our knowledgeable staff is available to give presentations to all ages, and we welcome opportunities to share our enthusiasm at your virtual outreach event. Feel free to send an email to if there are any images or slides you are wanting us to share.