Decatur drought mitigation

Summary

In 2011, Decatur, Illinois experienced a drought that required the City to activate its emergency water supplies. In 2012, a more severe drought hit the region before the emergency supplies had time to recharge, which resulted in near record low water levels and water use restrictions. To prepare for future droughts, the City worked with an engineering firm, Illinois regulatory agencies, and businesses within the community to identify and implement strategies to increase their water supply and readiness.

In 2010, the Illinois State Water Survey approached the City of Decatur to work on a drought-ready community project. They discussed how the community would react to a drought, identified key stakeholders, and deliberated the points at which they would need to implement voluntary and mandatory restrictions for water use.

In July 2011, Lake Decatur, the main water source for Decatur, a neighboring town, and large grain processors in the area, was full. A drought began in August. The City had to implement both voluntary and mandatory water use restrictions while also using emergency wells and a former sand and gravel pit to supplement the water supply. The drought was considered mild; the year’s precipitation was 15 percent below average and Lake Decatur returned to normal levels by January 2012. The City contacted the Illinois Environmental Protection Agency and began thinking about strategies to prepare for future droughts.

In the summer of 2012, Decatur was hit by another drought. The 2012 drought was more severe than 2011; precipitation was 32 percent below average and Lake Decatur dropped to nearly four feet below normal levels. In August of that year, the Sangamon River, the primary water source to Lake Decatur, recorded no water flow for 16 days straight. Additionally, some of the emergency water supplies had not fully recovered from the 2011 drought. To combat the drought and reduced emergency water supplies, the City had to implement some of the most rigid water use restrictions in the City’s history and began looking for additional emergency water supplies. While some late fall precipitation ended the drought, the City knew they needed to prepare for future droughts.

During the 2012 drought, the City researched multiple measures to replenish the water supply. They began building a temporary pipe to bring in water from a nearby private lake and investigated using treated wastewater. Neither of these options ended up being needed as the drought was over by the time they were operational. The City also hired an engineering firm to study where shallow groundwater wells could be placed. After some investigation, the firm determined none of the test sites would work due to high iron concentrations, low volume yields, or being located too close to other sources of contamination.

After the drought, the City looked for ways to increase their water supply to be better prepared for the next drought. The Decatur City Council decided to increase water rates over a period of three years by 119 percent. While this increase seems high, Decatur’s water rates were in the lowest 15 percent in central Illinois in 2012 and the increase put Decatur’s rates close to the area’s average.

In addition to the rate increases, the City issued bonds to dredge Lake Decatur and increase its volume. As a constructed water source, Lake Decatur had sediment built up that decreased the amount of water the lake could hold.

To determine additional actions the City could implement, they issued a Request for Proposals. The City selected INTERA, a geoscience and engineering firm, to complete a report determining a water budget and potential actions the City could complete to address supply gaps. Working with the City, the Illinois Environmental Protection Agency, and the Illinois Geological Water Survey, INTERA projected water demand and supply to 2050 and simulated a 10-month drought of record to determine how much additional water the City would need to meet the demand. Throughout the process, the parties also worked with  the City’s two largest companies and water users to ensure they would be able to access the amount of water they needed to continue to operate in Decatur and maintain economic stability.

Since the report was completed, the City has worked on some of the immediate recommendations, many of which were centered around improving the efficiency of the water supply network. The City continued proactive water main leak detection and has repaired and replaced deteriorating water mains at an accelerated pace to further reduce leaks and breaks.

The City partnered with Archer Daniels Midland Co., a local, water-intensive business, to help them identify alternate water sources they could utilize during a drought. The company built four wells on its property to use as alternative water sources in the event of a drought.

Funding

The City spent $92 million to dredge Lake Decatur, using money from rate increases to issue and pay for 20-year general obligation bonds. These bonds were classified as green infrastructure bonds, which allowed for lower interest rates. Over the 20-year period, the total cost will be around $160 million with interest.

The City spent $1.6 million in water capital funds to hire the engineering firm during the 2012 drought, and $277,290 to hire INTERA to conduct the report.

Archer Daniels Midland Co. also agreed to pay the City $2.5 million to help develop alternate water supplies.

Timeline

INTERA completed its report in 14 months, and, as of summer 2020, the City is still working on implementing its recommendations.

This project did not explicitly focus on equity and justice. For residents who were impacted by the rate increases, a local not-for-profit was available to help pay utility fees.