Observatories, facilities, equipment, personnel...

Nine US observatories - from Puerto Rico to California.

Existing and new resources - Sensor and communication networks, eddy flux towers, boreholes, gauges and much more (some previously built by LTER, Forest Service, et al.)

Community of researchers  - Collaborative teams work at the same field sites and encourage other scientists to take advantage of the CZO infrastructure.

A large field crew begins the process of hauling and constructing a flux tower for the Southern Sierra CZO.  Image: Southern Sierra CZO.

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Infrastructure Overview 

The National CZO Program is centered on nine observatories located in differing climatic and physiographic environments, from California to Puerto Rico. Each observatory is an environmental laboratory studying the chemical, physical and biological processes that shape Earth's surface on short-to-long time scales.  Support is provided by the US National Science Foundation (NSF), Geoscience Directorate, Earth Science Division.  An additional observatory, Christina CZO, is no longer funded by NSF.

Our Observatories >

A common approach 

Each CZO is working toward a common infrasructure while establishing additional resources that advance their unique strengths.

Our Shared Approach >


Ongoing collaborations exist with agencies and institutions that have either previously established infrastructure or are cost sharing new infrastructure. New additional partner institutions are encouraged.

Partner Organizations >

Individual or groups of researchers from outside the formal CZO program are encouraged to take avantage of the available infrastructure and data.  

Opportunities >


Infrastructure News


2017 CZO Webinar Series: Critical Zone and Society

06 Apr 2017 (National, Boulder, Calhoun, Catalina-Jemez, Christina, Eel, IML, Luquillo, Reynolds, Shale Hills, Sierra) - 2017 CZO Webinar Series: Critical Zone and Society.

Gobi Desert Dust Helps Sustain California’s Sierra Nevada

28 Mar 2017 (Sierra) - A team of researchers found that dust provides a much greater amount of nutrients to vegetation in the Sierra Nevada than previously thought.

Pushing the Limits on Water Isotope Measurement:  Lawrence Livermore and UC Merced

20 Dec 2016 (Sierra) - Lawrence Livermore and UC Merced researchers are tracking water through the critical zone using cutting-edge technology and new collection methods.


Four soil pits installed in new Research Area 8!

21 Nov 2016 (Calhoun) - Four soil pits were installed in new Research Area 8 at the Calhoun CZO on 21-22 November 2016 for easy access for soil sampling down to 2 meters.

Global warming experiment turns up the heat in Puerto Rican forest

27 Oct 2016 (Luquillo) - A pioneering research project is aiming to determine how forests in the Amazon, the Congo and elsewhere in the tropics will reacting to rising tempera

Critical Zone Q&A with researcher Adrian Harpold

19 Oct 2016 (National, Boulder, Catalina-Jemez, Reynolds, Sierra) - University of Nevada Reno's Adrian Harpold reflects on his past and present time researching at Critical Zone Observatories.

More News >


Boulder Creek CZO


"We study how erosion and weathering control Critical Zone architecture and evolution, concentrating on slope, climate, ecosystems, and rock properties."

Our CZO spans from the Continental Divide (4120 m) in the Front Range of the Rockies to the western edge of the Plains (1480 m). Our research takes advantage of large differences in elevation, climate, geologic history, and weathering regime.

Bounding lat,long: NW 40.158241, -105.700648; SE 39.847222, -105.002685
Approx center point lat,long: 39.977774, -105.356698

Calhoun CZO

South Carolina

"At the Calhoun, does reforestation of degraded landscapes mask or restore fundamental alterations in CZ hydrology, geomorphology, biology, and biogeochemistry?"

The Calhoun CZO is located in a region with an environmental history that involves some of the most serious agricultural land and water degradation in N America 5 themes:Ecohydrological Recovery; Biogeochemical Decoupling; Erosion-induced Carbon Dynamics; Human-CZ Interactions; Dynamic Persistence of Alternative States

Bounding lat,long: NW 34.662333, -81.782834; SE 34.544231, -81.649356
Approx center point lat,long: 34.6035, -81.7160

[Christina CZO is no longer active]

Christina River Basin CZO


"We integrate knowledge of water, mineral and carbon cycles to quantify human impact on Critical Zone carbon sequestration - from soils to sea."

Our CZO is located in the Piedmont and Atlantic Coastal Plain which provides drinking water to a million people in Delaware and Pennsylvania. Our research focusses on water, carbon and mineral fluxes (temporal and spatial integration), including human impacts.

Bounding lat,long: NW 40.16, -76.3; SE 39.4, -75.0
Approx center point lat,long: 39.698520, -75.626309

Eel River CZO


"Exploring how the critical zone will mediate watershed currencies and ecosystem response in a changing environment."

Bounding lat,long: NW 40.7263, -124.3490; SE 39.2406, -122.6680
Approx center point lat,long: 39.718588, -123.652794

Intensively Managed Landscapes CZO


"The Intensively Managed Landsapes CZO works to understand how land-use changes affect the long-term resilience of the critical zone."

Bounding lat,long: NW 46.352885, -97.363941; SE 39.611674, -88.142584
Approx center point lat,long: 39.98731004722222, -88.66616; 41.72710555555556, -91.77335833333333; 44.1677, -94.0034
Secondary Bounding lat,long:
Minnesota River: NW 46.3530, -97.3517 ; SE 43.2307, -93.0885
Clear Creek: NW 41.7680, -92.0185; SE 41.6530, -91.5615
Sangamon: NW 40.5670, -89.5405; SE 39.6110, -88.1425

Santa Catalina Mountains & Jemez River Basin CZO

Arizona/New Mexico

"We focus on measuring geomorphic, hydrologic, and biogeochemical interactions that drive theory and modeling of critical zone evolution."

Our CZO comprises elevation (climate) gradients on rhyolite, granite and schist in northern New Mexico and Southern Arizona. Our research is especially pertinent to climate variations of arid and semi-arid systems.

Bounding lat,long: NW 36.018774, -110.847624; SE 32.414320, -106.389630
Approx center point lat,long: 32.427379, -110.757822; 35.889167, -106.532206
Secondary Bounding lat,long:
Catalina: NW 32.5630, -100.8480; SE 32.4140, -100.7240
Jemez: NW 36.0188, -106.6724; SE 35.7826, -106.3895

Luquillo CZO

Puerto Rico

"We study how Critical Zone processes and water balances differ in landscapes with contrasting bedrock but similar climatic and environmental histories."

Our CZO is located in a forested, mountainous, and wet region of northeastern Puerto Rico. Our research compares two adjacent watersheds, which are underlain by differing bedrock types and exhibit differing weathering characteristics,

Bounding lat,long: NW 18.410405, -65.861106; SE 18.187889, -65.669475
Approx center point lat,long: 18.279715, -65.763837

Reynolds Creek CZO


"The Reynolds Creek CZO will address the grand challenges of improving prediction of soil carbon (C) storage and flux from the pedon to landscape scale"

Soil carbon is the largest terrestrial C store but remains a large source of uncertainty in global climate models due to scaling and process understanding. Reynolds Creek CZO is focused on the quantification of soil carbon and the critical zone processes governing it.

Bounding lat,long: NW 43.312983, -116.859446; SE 43.060888, -116.688138
Approx center point lat,long: 43.205809, -116.749823

Susquehanna Shale Hills CZO


"We emphasize quantitative prediction of Critical Zone creation and structure, focusing on pathways and rates of water, solutes, and sediments"

Our CZO is a forested, first-order catchment on shale bedrock in a temperate climate. Our research promotes understanding of how the forested catchment evolves over multiple timescales ranging from the meteorological to the geological.

Bounding lat,long: NW 40.731944, -78.073333; SE 40.589444, -77.846759
Approx center point lat,long: 40.65, -77.95

Southern Sierra CZO


"We investigate the critical zone across a mountainous elevation gradient, focusing on water balance, nutrient cycling, and weathering processes."

SSCZO is based in the southwestern Sierra Nevada with sites ranging from oak savannah to subalpine forest, crossing the rain-snow transition zone. Research at these sites focuses on water, nutrient, and soil fluxes; and landscape and climate changes cross space and time.

Bounding lat,long: NW 37.739566, -120.061087; SE 36.172095, -118.333915
Approx center point lat,long: 37.056960, -119.195966