Little Rock sits on the south bank of the Arkansas River, which has been the city’s primary water source since the city was founded. The Central Arkansas Water utility — serving over 400,000 people in the metro area — draws from both the Arkansas River and Lake Maumelle, a protected reservoir about 15 miles west of downtown.
Two Sources: River and Reservoir
The Arkansas River carries the runoff of a 161,000-square-mile watershed that extends all the way to the Colorado Rockies. By the time it reaches Little Rock, that water has passed through wheat fields in Kansas, oil country in Oklahoma, and poultry operations in northwest Arkansas. The nutrient load, particularly nitrate and phosphorus from agricultural runoff, is substantial — especially during spring flooding.
Lake Maumelle is different. Central Arkansas Water owns the watershed around Lake Maumelle and maintains strict development restrictions to protect water quality. The reservoir is designated as a Sole Source Aquifer alternative water supply and provides a higher-quality backup source when the Arkansas River is turbid or contaminated.
During major flood events on the Arkansas River — which have been severe in recent years, with record flooding in 2019 — the river carries elevated sediment, bacteria, and agricultural chemicals. Central Arkansas Water’s treatment plant on the Arkansas River handles up to 100 million gallons per day but requires more intensive treatment during flood periods.
Agricultural Chemicals: Nitrate, Atrazine, and Poultry Waste
Northwest Arkansas — the corridor around Fayetteville, Bentonville, and Rogers — is one of the most intensively poultry-farmed regions in the country. Tyson Foods, Simmons Foods, and other major integrators have thousands of contract growers producing broilers and turkeys in concentrated animal feeding operations (CAFOs).
The waste from those operations — applied to fields as fertilizer — contributes substantial nitrogen and phosphorus to the Illinois River, the Buffalo National River watershed, and ultimately the Arkansas River. This nutrient loading has been the subject of ongoing litigation between Oklahoma and Arkansas over the Illinois River, which flows from Arkansas into eastern Oklahoma.
Atrazine, the herbicide used heavily in corn production across the Great Plains, reaches the Arkansas River from Kansas and Oklahoma. Little Rock’s treatment plant monitors for atrazine seasonally; levels have generally been below the MCL but spike during spring applications.
Poultry litter also carries pathogens — Campylobacter, Salmonella, E. coli — that require effective disinfection at the treatment plant. Central Arkansas Water uses chloramine disinfection, which is effective against most pathogens but less effective against Cryptosporidium.
Natural Arsenic in Groundwater
Arkansas has significant naturally occurring arsenic in groundwater, particularly in alluvial aquifer systems along the Arkansas River and in the Mississippi Embayment aquifer that extends across eastern Arkansas.
For Little Rock’s municipal supply — surface water treated at a plant — arsenic isn’t typically a concern. But for the rural communities around Little Rock using private wells or small groundwater systems, arsenic is a real issue. The Arkansas Department of Health has documented numerous domestic wells in Pulaski, Saline, and surrounding counties with arsenic above the EPA’s MCL of 10 ppb.
The geology of the region concentrates arsenic in reducing groundwater environments — the same conditions that can produce iron and manganese problems common in Arkansas wells. Residents on private wells in the Little Rock metro area should include arsenic in routine water testing.
Aging Infrastructure and Lead
Little Rock’s water distribution system dates back to the late 1800s, and lead service lines remain in older parts of the city, particularly in the historic neighborhoods closest to downtown. Central Arkansas Water has been working on lead service line identification and replacement.
The utility adds orthophosphate for corrosion control and has historically tested below federal lead action levels. Arkansas Act 1214, passed in 2021, required public water systems to create lead service line inventories, which has given Central Arkansas Water better data for its replacement planning.
Drought and Climate Variability
The Arkansas River is highly variable. It can run near-flood stage in spring and drop to a trickle in late summer during drought years. During the 2011-2012 drought, flows were critically low and water quality in the river degraded as contaminants became more concentrated and algal growth intensified.
Lake Maumelle’s protected watershed provides insurance against drought — the reservoir can supply the city for several months even during extended dry periods. But prolonged drought would eventually strain even that reserve, and climate projections for Arkansas suggest more frequent and intense drought episodes.
What Little Rock Residents Can Do
Central Arkansas Water provides treated water that meets federal standards. Key considerations:
- Review the annual CCR — available from Central Arkansas Water, covering the Arkansas River and Maumelle sources.
- Test for lead if you’re in an older home in the historic city core.
- Private well users in Pulaski and surrounding counties: test for arsenic, nitrate, and bacteria annually.
- Stay informed during flood events — the utility will issue advisories if source water conditions require any precautionary notices.
If you’re concerned about your water quality, a certified water treatment professional can help you test your water and recommend the right solution for your home.