Streams Monitoring in the Sonoran Desert and Southern Plains

Riparian habitats make up less than 2% of the land area in the American Southwest. They also support the highest density and abundance of plants and animals of any habitat type. Streams and associated riparian areas are critical to the ecological integrity of the region.

Person walking along the bank of a stream
West Fork of the Gila River, Gila Cliff Dwellings NM


Riparian areas supply food, cover, and water for a variety of wildlife. They also serve as migration routes and habitat connectors. Riparian corridors help control water pollution, reduce erosion, mitigate floods, and increase groundwater recharge. Riparian systems perform numerous ecosystem functions important to human populations. Yet they are one of the most endangered forest types in the United States.

For these reasons, streams were chosen as a focus for monitoring in the National Park Service Sonoran Desert Network and Southern Plains Network. Portions of several major river systems (or their tributaries) are found within parks of both networks.

Long-term monitoring of streams helps us to better understand aquatic and riparian ecosystems. This monitoring measures 10 ecological indicators: stream channel morphology (pattern and geometry of a stream channel); riparian vegetation community dynamics; exotic plant species status & trends; exotic plant early detection; core water quality parameters; nutrient dynamics; microorganisms; pollutant metals; surface water quantity; and aquatic macroinvertebrates. Fish will be monitored as funding is available.

Monitoring Objectives

The goal of streams monitoring is to detect broad-scale changes in aquatic and riparian ecological condition by observing selected ecological drivers, stressors, and processes. Specific, measurable objectives are to determine status and long-term trends in:

Stream channel morphology

  • Cross-sectional area, sinuosity(a measure of how meandering the stream is), channel slope, and sediment size distribution

Riparian vegetation

  • Cover of dominant and common (>10%) perennial riparian species
  • Frequency of uncommon perennial species and selected non-native invasive annual and perennial species

Core water quality parameters

  • Daily, seasonal, and annual core water quality parameters (temperature, specific conductivity, pH, dissolved oxygen, turbidity)
  • Seasonal and annual total nitrogen, total phosphorus, selected metals, and E. coli (when possible)

Surface water quantity

  • Seasonal and annual base flow
  • Frequency, magnitude, and duration of low-flow and flood events
  • Extent of wet and dry areas

Aquatic macroinvertebrates

  • Abundance of selected species and community structure
  • Selected multimetric indicators of biotic integrity - measures of stream condition that are based on the status of the living organisms within it.


  • Fish communities on local and regional scales


Staffperson calibrating equipment used for monitoring
Calibrating equipment in the field.


Stream channel morphology
Using survey-grade equipment, we locate 11 evenly distributed, permanent channel cross-sections in each stream segment in a park. We create a longitudinal profile to characterize stream slopes and depth, map habitat units, and perform particle-size surveys throughout each segment.

Riparian vegetation
Vegetation is sampled on 20-m transects along each of the 11 permanent channel cross-sections. Vegetation data are recorded within three structural categories using the point-intercept method. Points are spaced every meter. Soil cover is recorded to substrate class (e.g., sand, gravel). In the two meters surrounding the transect, frequency is recorded for plants not encountered during point-intercept sampling. Data on tree and shrub recruitment are collected in a 20-m-wide band transect surrounding the permanent cross-section. Extremely large trees are mapped and vigor measurements are collected (e.g., basal area, height).

Core water quality parameters
A multiparameter datalogger (sonde) collects continuous core water quality measurements at 15-minute intervals for two weeks seasonally at each index site. Nutrients, inorganics, metals contaminants, and E. coli samples are collected quarterly.

Surface water quantity
Stream discharge measurements are collected from U.S. Geological Survey stream gages in or near the parks. Staff gages, crest gages, and logging pressure transducers are used to collect data in stream segments.

Aquatic macroinvertebrates
Macroinvertebrates are collected in stream riffles for determining trend and for comparison with state indices of biotic integrity (IBIs), and in all habitats at each index reach. Methods are designed to be directly comparable to state and federal (Environmental Protection Agency, National Water-Quality Assessment Program) methodologies.

The networks are working with adjacent land management agencies and state departments of fish and game to monitor fish communities in and around the parks, enabling the data to be analyzed in a regional context. Methods include electrofishing and seining.

Products, Scope, and Schedule

For each park, an annual summary report is produced, documenting effort and initial findings for the previous water year (October–September). Comprehensive status and trends reports are produced after five years of data collection and provide a more detailed assessment of aquatic and riparian condition. The scale of inference is the individual park.

Streams information is also communicated through live presentations, resource briefs and other written summaries, and other media produced and distributed through the network websites and the Science of the American Southwest site.

The monitoring protocol and standard operating procedures were published in 2018. A database and supporting documentation that meet NPS and Federal Geographic Data Committee standards are complete and available. Data availability varies by parameter and park; please check with the Project Contact (below). 

Parks where streams monitoring is being implemented
Start Year Park Network
2011 Bent’s Old Fort NHS Southern Plains
  Washita Battlefield NHS Southern Plains
2010 Chickasaw NRA Southern Plains
  Lyndon B. Johnson NHP Southern Plains
  Pecos NHP Southern Plains
2007 Montezuma Castle NM Sonoran Desert
  Tumacácori NHP Sonoran Desert
  Tuzigoot NM Sonoran Desert
2003 Gila Cliff Dwellings NM Sonoran Desert

 NHP = National Historical Park; NHS = National Historic Site; NM = National Monument; NP = National Park; NRA = National Recreation Area


Project Contact

Evan Gwilliam, Sonoran Desert Network, (520) 403-3055


Originally prepared by Andy Hubbard and Evan Gwilliam, Sonoran Desert Network Network, 2010. Updated 2016.

Last updated: February 14, 2019