Measuring Green Infrastructure: USGS Stormwater Studies in Chicago, St. Louis and Beyond

In towns and cities, stormwater is hard to manage: how much must be carried away depends on changing land cover and unpredictable rain. It also causes flooding and is a major source of pollution, washing trash, bacteria, heavy metals and sediment into streams.

Traditionally it's handled with gray infrastructure — gutters, culverts, sewers and tunnels — which moves water efficiently but filters nothing. In many older cities, combined storm and sanitary sewers mean either huge volumes of wastewater to treat, or untreated water released into rivers during storms.

Green infrastructure

More and more communities are adding green infrastructure (GI) — pervious surfaces that let water through, grassed swales, bioretention basins and rain gardens — which use soil and plants to absorb and filter stormwater where it falls. GI can cut the amount of runoff and the pollution it carries, reduce the need for new storm sewers, improve nearby streams, and look better.

Green infrastructure: a rain garden, pervious pavement and vegetated swales. From U.S. Environmental Protection Agency, 2021

With green infrastructure, a developed area behaves more like a natural one: less runoff, more evapotranspiration, and more water soaking into shallow and deep groundwater. From Baker and others (2022), modified from the Federal Interagency Stream Restoration Working Group (1998)

The USGS Central Midwest Water Science Center (CMWSC) and its partners install, calibrate and run instruments to measure how GI changes flooding, water movement and water quality.

Chicago schoolyards

At two schools on Chicago's South Side — Virgil I. Grissom Fine and Performing Arts Elementary and Morrill Math & Science Specialty School — the USGS monitors runoff and water quality. Grissom's schoolyard, once all asphalt, is now about 50% GI, with pervious pavement and rain gardens.

Runoff instruments at Grissom Elementary: a six-inch V-notch weir and a sewer flow meter in a line draining the green infrastructure. Clint Bailey, USGS

• At Grissom, instruments compare runoff from the impervious track with runoff from the GI, and groundwater sensors sit near the track and beneath a rain garden.
• At Morrill, flow meters and acoustic sensors are in the storm sewers leaving the GI, with groundwater sensors in an on-site retention basin and around the property's edge.
• Weather data — rain, humidity, pressure, temperature and wind — help judge how the GI performs in individual storms.

Great Lakes stormwater projects

Since 2015, the USGS has worked with the EPA through the Great Lakes Restoration Initiative to measure how much stormwater GI removes, mostly by monitoring sites before and after construction. Because that covers only a few of the many designs, soils and land uses across the Great Lakes states, the USGS built a way to pool data on GI practices across the basin, so statistics can show how design, land use, soils, vegetation and maintenance affect performance — and guide decisions on future GI.

A low-cost flood alert network

Under the USGS Next Generation Water Observing System (NGWOS), which includes the Illinois River Basin, the CMWSC and the Village of Harwood Heights, Illinois, built a flood alert system. Eight sites, chosen from residents' experience of flooding, have sensors measuring water in manholes and above the street, linked by a LoRaWAN long-range network to an online dashboard. The sensors and gateway cost about a quarter as much as typical monitoring equipment.

Low-cost water-level sensors in Harwood Heights. William Selbig, USGS

The flood alert dashboard, showing water-level and rainfall data. William Selbig, USGS

When a sensored intersection floods, automated text messages or a roadside display alert officials and the public. Where money for big sewer replacements isn't available, such systems help protect life and property — and could also measure the effects of GI.

Demolished buildings in St. Louis

A shrinking population has left thousands of vacant properties in St. Louis. Demolishing them removes impervious area, in line with the Metropolitan St. Louis Sewer District's Project Clear, which aims to reduce rain runoff into the sewer system. The USGS and EPA, with the city and the sewer district, compared "legacy" (standard) and "green" demolition — which differ in whether the foundation is treated or fully removed, and in the depth and texture of the fill soil.

Deconstruction removes impervious surfaces and replaces them with soil that can hold stormwater. David Heimann, USGS

Ten pairs of legacy and green lots, chosen at random, are monitored for groundwater, infiltration, soil conductivity and compaction, with soil moisture and temperature logged every 5 minutes at 10-cm steps down to 90 cm. A nearby restored prairie serves as the control — the best the local soils can do.

A legacy and green demolition pair in St. Louis.

Installing a piezometer at a St. Louis demolition site. David Heimann, USGS

The Grove at Bloomington, Illinois

In 2006, the City of Bloomington restored 2 miles of Kickapoo Creek in a 90-acre park near The Grove, a residential development, aiming to reduce nutrients, support diverse wildlife, and manage sediment and stormwater. The USGS measured streamflow, groundwater, sediment and water quality (dissolved oxygen, pH, temperature, conductance and nitrate) with three streamgages — two upstream, one downstream — plus wells and monitors, to see how runoff changed as it passed through the restored creek and wetlands. State fish and biology surveys showed how well it supported fish, invertebrates and plants.

The Grove restoration site, Kickapoo Creek watershed, McLean County, Illinois. From Roseboom and Straub (2013)

Sources

Based on Allison Atkinson, David Heimann and Clinton Bailey, "Hydrologic investigations of green infrastructure by the Central Midwest Water Science Center," U.S. Geological Survey Fact Sheet 2023–3043, USGS; a work of the United States government in the public domain. It cites Baker and others (2022), the EPA (2021, 2023), Heimann and Reiss (2021), Roseboom and Straub (2013) and others.