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Water Management

We are committed to protecting and minimizing our impact on natural resources by reducing our water use and returning clean water to our environment. We are targeting a 95% reduction of water withdrawn for thermal generation by 2045, according to a 2005 baseline. We have made progress toward our target by already reducing withdrawal by 140 billion gallons annually since 2005.

Operations at our facilities comply with regulatory standards established by the federal Clean Water Act and state-issued permits. In addition, our water management approach goes beyond those mandates and includes processes to protect freshwater and groundwater in the regions where we operate as well as reducing consumption where possible.

A minus.

We received an A- on our 2021 CDP Water Security Questionnaire. The average scores for North America and Energy Utility Networks were B- and B, respectively. The CDP details our use of water resources and management strategy for the water resources we use. Our latest response to the CDP, as well as other reports related to water management, can be found in our ESG library.

We regularly evaluate water-related issues as part of our overall business strategy and long-term financial planning. In 2018, we conducted a Water Resiliency Assessment that assessed the current and future availability of water resources and potential water stress in our regions of operation and key portions of our supply chain. This information is helping us better plan for our business’s future water needs.

Water Management At-a-Glance

Approximately 16.5 trillion gallons of water withdrawn in 2021, and 99% returned to the environment

Targeting 95% reduction in water used for thermal generation by 2045 (2005 baseline)

Water consumption intensity of 132 gallons per MWh generated in 2021

How We Use Water

The majority of water we use is fresh surface water that comes from the Mississippi, Missouri, and Osage rivers. Most of this is used for clean hydroelectric power generation, which contributes to Ameren’s goal to achieve net-zero carbon emissions by 2045. Ameren Missouri operates three hydroelectric energy centers that harness freshwater and pumped water to create power. Water releases from these facilities are monitored and managed to meet regulatory criteria.

Freshwater is also used for non-contact thermal cooling at our nuclear and coal-fired energy centers. A small fraction of water is used for non-cooling purposes, which is treated in our wastewater treatment systems before it is discharged back to the river from where it came. All water is closely monitored in accordance with our specific permit limits and 99% of what is withdrawn from river systems is safely returned to the environment.

Total water withdrawal and thermal generation water withdrawal pie charts.

Recycled water is used at several of our facilities. For example, the Taum Sauk Energy Center features a closed-loop system that continuously reuses water, as well as the cooling system at our Callaway nuclear energy center.

In addition, we have transitioned all coal-fired energy centers to dry ash handling, which has also contributed to our reduced overall water use. Read more about our coal combustion residual (CCR) management efforts.

Water reduction targets for thermal generation.

Water Reduction Targets

We are targeting a 95% reduction in water withdrawal for thermal generation (i.e., all non-hydroelectric generation) by 2045, with interim targets of 40% by 2030, and 75% by 2040, compared to 2005 levels. Our water reduction targets coincide with the retirement of our coal-fired energy centers, as presented in Ameren Missouri's Integrated Resource Plan. 

As of December 31, 2020, we reduced water withdrawal for thermal generation by 10% from 2005 levels, representing approximately 140 billion gallons of annual water savings. This reduction is due to the retirement of two coal-fired energy centers, and recent investments to convert to dry ash handling at our coal-fired energy centers.

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