Where does Dallas get its water? How much water can Dallas supply?
Dallas gets its water from seven sources, included are six lakes, also called reservoirs (Lake Grapevine, Lake Lewisville, Lake Ray Hubbard, Lake Ray Roberts, Lake Fork, Lake Tawakoni) and one river system (Elm Fork of Trinity River). Of all of these, Lake Ray Hubbard is the only reservoir that the City of Dallas owns and operates. Dallas and other municipalities share the rights to extract water from the other six places.
What is Dallas’ rainfall like and what is its importance?
Dallas’ yearly 38.3 inches of rainfall is essential to Dallas’ water supply. Rainfall fills the reservoirs, and after a wet 2021, the reservoirs are all above 85% capacity, with the exception of Lake Fork, which is only at 72% due to repair work occurring at its dam. All of these reservoirs are at a lower level, consistent with yearly water level fluctuations. Dallas is very lucky to have a predictable amount of yearly rainfall. As climate change continued over the past few decades, the western part of the United States has become dryer, while the eastern part of the United States has become wetter. Dallas is right in the middle of United States, and the city has maintained a seemingly predictable amount of yearly rainfall for the past 150 years. The seven lakes/rivers and annual rainfall allow Dallas to have a sustainable water supply capacity of 502 million gallons per day (MGD).
What is Dallas doing to increase the water supply?
Because of rising water demand driven by population growth, Dallas’ current lakes and reservoirs will not be able to sustainably supply the city with water past 2030, and Dallas is estimated to run out of water in 2035. As a result, the City of Dallas has approved, funded, and is currently working on connecting three more water sources and building a reservoir to extend its water supply through 2070. Dallas will do this through four main projects: The Integrated Pipeline Project (IPL), connecting Dallas to to Lake Palestine; Indirect Reuse through a Balancing Reservoir; a connection to the Neches River; and a connection to Lake Columbia. These projects will be completed by 2027, 2050, 2060, and 2070 respectively, and are projected to increase the water supply to 850 MGD (a 350 MGD increase) and keep Dallas’ water sustainable even as the population doubles by 2070.
Dallas’ first of four projects is the Integrated Pipeline Project (IPL). The IPL is the construction of over 150 miles of pipelines, three new intake pump stations (one for Lake Palestine, one for the future Neches River project, and one for the future Lake Columbia project), and three new booster pump stations (to help move the water towards Dallas at a faster rate). The 9-foot pipe will connect Lake Palestine to Joe Pool Lake where another pipeline will take the water to Bachman Water Plant to be cleaned and treated. The IPL is currently slated for a 2027 completion, and this project will provide Dallas with an additional 102 MGD, and it will help Dallas meet demand through 2050.
The second project is called Indirect Reuse through a Balancing Reservoir where Dallas will construct a reservoir to store discharged non-potable water from the wastewater treatment plants so that Dallas can treat the water and then use the water as needed. This project will be completed by 2050, and it will increase Dallas’ water supply by 102 MGD, bringing the total supply to over 750 MGD.
The third project is the connection to the Neches River. The Neches River runs south out of Lake Palestine, and the intake pump station, created in the IPL, will pump water through a pipeline to Lake Palestine. This water will then get pumped through the 90-mile pipeline, created in the IPL, back to Dallas where it will be sent to Bachman Water Plant to be cleaned and treated. This project will supply an additional 42 MGD, bringing the water supply capacity to almost 800 MGD.
The final project slated to be complete before 2070 is the connection to Lake Columbia. Lake Columbia is located 20 miles east of Lake Palestine. Similar to the Neches River connection project, an intake pump station will pump the water from Lake Columbia to Lake Palestine, via a pipeline, where it will go inside the same 90-mile pipeline to Joe Pool Lake. The project will supply an additional 42 MGD, bringing Dallas’ water supply capacity up to almost 850 MGD.
Sourced from: https://www.dallascityhall.com/departments/waterutilities/DCH%20Documents/2014_LRWSP_Final_Report_all_11302015.pdf
Image: projected water supply until 2070. The red line represents raw water demand, and the colored sections represent the daily quantity of water supplied by different projects.
What is the total cost of these projects?
Dallas will spend a total of $3.914 billion on DWU’s water projects between 2020 and 2070. The four main water supply projects mentioned above will cost a total of $1.851 billion ($1.097 billion for the IPL, $675 million for the Balancing Reservoir, $227 million for the Neches River Connection, and $160 million for the Lake Columbia connection). Not only is DWU executing the above four projects, but DWU is executing sixteen other projects, between 2015 and 2070, to improve existing infrastructure. These projects will cost $2.063 billion, and plan to execute expansions to existing water plants, expansions to an existing balancing reservoir, and improvements to the filters at the water plants.
What are the other lakes in the Dallas area used for?
There are eight other smaller lakes in the Dallas area that are not connected to the Dallas Water Supply, including Bachman Lake, Joe Pool Lake, Mountain Creek Lake, Lemmon Lake, North Lake, Fish Trap Lake, Lake Cliff, White Rock Lake, and Parkdale Lake. Water in half of these lakes (Joe Pool Lake, Mountain Creek Lake, White Rock Lake, and North Lake) is used as a coolant for Dallas Power and Electric Plants. Bachman Lake is used for municipal water storage. Lemmon Lake used to be a one-of-a-kind wildlife area but has since dried up due to a breach in the earthen dam.
Sourced from: https://www.pinterest.com/pin/54254370480747272/
Image: White Rock Lake in Dallas
What is the nature of the infrastructure in the Dallas water system?
Dallas has 3 different water treatment plants, 2 wastewater treatment plants, 22 pump stations, 15 wastewater pump stations, and 21 storage tanks. Dallas has over 5,000 miles of water main pipelines 4,000 miles of wastewater main pipelines, and 3,000 miles of storm drain pipelines.
Dallas’ water treatment plants treat water from DWU’s reservoirs daily. Together, these three water treatment plants have a water treatment capacity of 900 MGD. These water treatment plants supply Dallas with clean drinking water every day. The Eastside Water Treatment Plant produces almost 63% of Dallas’ clean water, or 314 MGD to around 2.2 million people. The Elm Fork and Bachman Water Treatment Plants, together, produce the remaining 37% of Dallas’ daily drinking water, or about 188 MGD to around 1 million people per day.
Dallas’ two wastewater treatment plants clean wastewater so that the water can go back into the environment: places like local creeks, lakes, and the Trinity River. However, this water is not potable, and it still needs to be treated before it can be used for human consumption. The two wastewater treatment plants, Southside and Central Wastewater Treatment Plants, can clean up to 260 MGD. However, the plants only treat around 160 MGD combined as that is how much wastewater DWU’s customers produce per day.
Dallas’ 22 pump stations pump clean water to DWU’s customers. These pump stations pumping capacity is anywhere between 50,000 and 900,000 gallons per minute, or between 72 MGD and 1,200 MGD. The large gap is due to the age of the pump stations. Some of Dallas’ pump stations are from the 1930s and can pump 50,000 gallons per minute. The newest pump stations can pump upwards of 900,000 gallons per minute. The water from these pump stations goes into the water pipelines and to DWU’s customers to be used.
15 wastewater pump stations are dotted around DWU’s 700 square mile service area. These pump stations pump wastewater from DWU customers to the wastewater treatment plants. Together, these pump stations can pump over 4.7 BGD, but currently, they only pump 160 MGD.
Dallas’ 21 storage tanks help store water for their service area. There are 9 above ground tanks and 12 underground tanks. Although these storage tanks do not have a minimum storage capacity requirement, they must meet the storage and fire demands of its service area.
Dallas’ thousands of miles of piping carry water miles to its various destinations. Dallas has three different types of water pipelines: water mains, wastewater mains, and storm pipes. Dallas has 5,000 miles of water mains, 4,000 miles of wastewater mains, and 3,000 miles of storm pipes. Most of these pipes range between 4” and 120” in diameter, and carry water to different parts of the city.
Image: Ariel view of Dallas' Southside Water Treatment Plant
What are some upgrades that Dallas is doing maintain its current and future infrastructure?
While Dallas’ infrastructure is effective, almost two thirds of it is over 30 years old. Dallas is trying to solve its number one problem, aging infrastructure, by constantly replacing old parts of the water system. Dallas is also renovating and replacing various essential infrastructure, including the water/wastewater treatment plants, the pump stations, the storage tanks, and piping. Here are some examples:
The Eastside Water Treatment Plant recently had some renovations done to increase its capacity to store clean, treated water. Four 16-million-gallon concrete tanks were added, increasing the capacity of treated water to 64 million gallons. This water can be sent to customers at a moment’s notice. All four tanks were completed on time and within budget. By 2024, the Eastside Water Treatment Plant will provide water to over 3 million people.
The Elm Fork Water Treatment Plant will have its filter complex replaced. This replacement was part of DWU’s long term planning. According to Mark S. Swain, City of Dallas Auditor, “The Elm Fork Water Treatment Plant Filter Complex has reached the end of its useful life and the project plans to improve water quality and filtration efficiency. The project was estimated to cost between $130 million and $145 million.”
The Walcrest Pump Station had a complete rebuild. After being demolished, construction started in 2014 and finished eight years later in the spring of 2022. The Walcrest Pump Station was over 50 years old, so replacement parts were hard to find, and the equipment did not meet the current standards. The new Walcrest Pump Station now serves over 850,000 residents with clean water daily.
Dallas’ pipes are also in need of being replaced. Around 1% of the piping is replaced per year, but Dallas has plans to increase annual pipe replacement so that the DWU water system can continue to run smoothly and serve its customers daily.
To maintain its future infrastructure, DWU must increase its operating budget. DWU is increasing its water rates so that the organization can increase its $500 million operating budget to cover the additional maintenance costs that come with the new infrastructure.
How is the water treated to make sure that it is safe and clean?
According to the City of Dallas, “DWU uses chemical treatment, settling, filtering and disinfection to purify drinking water. The chemicals we use include chlorine and ammonia (which combines to make chloramine) or ozone to disinfect the water; lime and iron sulfate to remove suspended solids in the water and for corrosion control; activated carbon to control offensive tastes and odors; and fluoride to help prevent tooth decay.
“We use chloramine instead of chlorine to protect the health and safety of our citizens. Studies have shown that using chlorine by itself can cause a reaction in the water that leaves by-products called trihalomethanes. Some studies indicate that trihalomethanes could be harmful if consumed in large quantities over long periods of time. Dallas water is considered non-corrosive, which means that it is less likely to leach lead from pipes than water that is corrosive.
“The combination of our treatment processes and the non-corrosive nature of Dallas water results in exceptionally high quality, safe drinking water. In fact, in 1991, DWU won the Environmental Protection Agency's Region 6 Environmental Excellence Award for Public Water Supply. Recently, Dallas was notified that it will again receive this prestigious award. That means that Dallasites are drinking some of the best water in five states: Texas, Arkansas, Oklahoma, Louisiana, and New Mexico.”
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