Trutta Environmental Solutions are the developers of the High Definition Stream Survey (HDSS) method, a peer reviewed technique that integrates cutting edge technology to make stream and river data collection faster, less expensive and more thorough than traditional collection methods.

In comparison to HDSS, traditional stream sampling method surveys are based on point samples or descriptions of short (several 100m) sections of streams or rivers. These traditional approaches collect information on a small percentage of total aquatic habitats and then extrapolate the findings between sampling sites to fill in the gaps. It is not uncommon for a few hundred meter survey site to be considered representative of 20 or more miles of adjacent stream. Extrapolation of data has long been known as a major source of error and may completely miss problem areas if they fall outside of a sample location. The HDSS approach provides continuous surveys of the entire river segment and cross-sectional transects to provide the necessary geomorphic measurements for dealing with water quantity issues.

Not only does the HDSS approach deliver a more complete data set than traditional surveys, but it is also less expensive. HDSS methods require fewer people and less time in the field and thus cost less than traditional survey methods. The speed of data capture and lower costs when using the HDSS approach allows for greater distances of river to be surveyed. While traditional surveys use different methodology to gather cross section profiles in wadeable and non-wadeable sections, the boat- or backpack-mounted HDSS can gather all the necessary data from a single platform and thus provides more consistency of the results while still collecting the data at a greater speed.


How does a High Definition Stream Survey (HDSS) provide better data and support better decisions?
Having better data is at the heart of better decision-making. Better data needs to be relevant, accurate, complete, consistent, and up to date.

Relevant – Applying HDSS saves you time and money by documenting the relevant information required to answer your questions. Additionally, HDSS data is easily reviewable for additional classifications when needed. The data can also be summarized at a scale appropriate to the problems you encounter. HDSS excels at multiscale analysis.

Accurate – Collecting direct imagery allows problems and issues to be easily and clearly observed and documented. Results and statistics are directly linked to the reviewable imagery.

Complete – These surveys are a census of the conditions within the river, not a series of subsamples. Having a census allows for nearly all possible conditions including the rare or less observed conditions to be documented. These rare or less observed conditions often have a considerable impact on desired conditions and outcomes.

Consistent – Continuous data is consistently collected at a near 1 meter longitudinal resolution along the entire survey area (typical survey areas around 1 to 100km). This consistent data resolution allows for accurate and meaningful comparisons among the different parameters of interest and reduces the overall complexity (difference in scale and precision) of the analysis.

Up to Date – HDSS data is collected, organized, analyzed, and synthesized in a short period of time. A typical project of 50km can be completed within a few months.

Converting Data to Decisions – Having better data is not the only thing needed for better decisions. Data needs to be organized into useful information, converted to knowledge about your system and then used to support your decisions. HDSS utilizes innovative data collection platforms and software that collects, organizes, analyzes, and synthesizes complex river and stream data, enabling data- driven decision-making. The simplicity of analysis and the generated outputs create an environment for collaboration between scientists, policymakers, and stakeholders to discuss and develop meaningful management actions. With an evidence-based understanding of all the conditions influencing the river or stream you can make better, more appropriate, decisions to improve existing conditions.



Prioritization is the process of deciding the relative importance or urgency of things. Many restoration and rehabilitation projects are undertaken ad hoc, without a clear prioritization of conditions along the entire stream corridor (e.g., conditions throughout the stream corridor are not fully understood). These ad hoc projects often fail to reach their full potential due to overriding problems at other locations within the stream corridor.

The HDSS approach increases the success of each project by identifying what problems exist, their severity, and the spatial arrangement to ensure accurate prioritization. HDSS systematically documents the type, severity, and location of problems within your stream corridor. This information is easily used to prioritize areas for restoration or rehabilitation based on type, severity, and/or location. Additionally, locational data is easily used to identify the scope of a problem, such as 800m vs 25m of non-functional streambanks.

By applying the HDSS approach, you benefit by:

  • Understanding the physical and biological conditional along your stream.
  • Achieving your project objectives and goals most effectively based on importance, available resources, political boundaries, etc.
  • Prioritizing your management actions based on your objectives. This can be accomplished simply by using the problem, type, severity, and location/scope;
  • Developing custom suitability models using specific suitability criteria.
  • Common criteria used in these suitability models include the distance from roads, property owners, and jurisdictions, along with parameters assessed (e.g., stream corridor condition, streambank function, depth, relative cost, functional uplift, etc.).
  • Changing management direction as priorities evolve, objectives are accomplished and resource allocation change, these models can easily be updated with new data for reprioritization.

Suitability Model for Habitat enhancement (example)

In the image below, an organization wanted to increase the in-channel structure for fish to increase angler success. The fish was structure-oriented, thus more cover should equal more fish. To accomplish this we first classified the streambed roughness from very smooth (little to no habitat: fine and sand sediment) to very rough (habitat present: large rocks and boulders) as a measure of instream habitat to determine where and how much habitat is currently available. Then we utilized ecological lift, accessibility (e.g., distance from road/river access site), and relative cost as prioritization criteria. When this criterion was incorporated into the model, two locations were identified for instream habitat development (left) based on location with the greatest accessibility (e.g., distance from road/river access site), highest ecological uplift, and lowest relative cost.


Humans have altered the rivers and streams at various spatial scales. These scales range from small stormwater outfalls and residential water intakes to large reservoirs that span entire states or regions. To best address your management questions, you must understand how the parameter persists within your system and at what scale can you best address your management objectives.

HDSS was designed for Multiscale Assessments. This allows you to view and analyze parameters at multiple scales or levels of detail; therefore, allowing you to develop management strategies at a scale relevant to your management plan. HDSS continuously samples the range of conditions along the entire stream corridor. Each parameter is collected at a near identical spatial resolution so HDSS data can easily transition among the multiple scales.

HDSS easily allows you to spatially scale your assessment from large management units (e.g., parks, districts, entire rivers, etc.) to small management units (e.g., specific sites of concern <500m). These multiscale assessments easily allow for intra- and/or interagency comparison of parameters allowing for comparisons along the same spatial scale (e.g., management units). These assessments can be performed on any parameters collected at any scale.

By applying the HDSS approach, you benefit by:

  • Understanding the physical and biological conditional along your stream.
  • Quickly and accurately transition among spatial scales to identify distinctive trends at various levels.
  • Quickly and accurately assess data at the appropriate spatial scale for each goal or objective.
  • Understanding the spatial arrangement of unique characteristics along the river or stream.
  • Easily review the HDSS StreamView video for additional data needs.
  • Easily integrate species data or additional habitat assessment for a more complete understanding.

The examples below demonstrate a multiscale assessment of streambed, streambanks, and riparian functions. At the large scale (e.g., entire park) we can easily see that the majority of the streambed, streambanks, and riparian are functional or better. As we compare the mainstem river and the major tributaries we can easily see that the function of the streambed and streambanks within the tributaries are much lower than the mainstem; however, the function of the riparian is less than that of the mainstem. As we continue to scale down on the mainstem river we compare the segments. Here we can easily see which segments are in need of management action based on the elements of interest (i.e., streambed, streambank, or riparian). Then we compare among tributaries to again identify which tributaries are in need of management action based on the elements of interest. Finally, a prioritized list can be created, based on a desired unit of interest (<500 m in this case) and parameter (function in this case), identifying specific sites in most need of management action. This prioritization can be done with any parameter at any level based upon your need.


Entire management area (mainstream and tributaries combined)
Mainstem vs. tributaries comparison
Individual river segment comparison
Individual tributary comparison
Example of specific site of concern


A Riverscape Assessment is a continuous river view that spatially incorporates all unique characteristics along the riverine environment. Currently, most research is occurring on the microhabitat (1-10 m), reach (10-1000 m), and drainage basin (100-1,000 km; e.g., remote sensing) scales. Data independently collected at these scales often fails to contain all the necessary information so they are combined. However, when combined, a gap in information exists between the reach and drainage basin levels, the segment level (1km – 100km), that limits the value of the resulting information.

HDSS was designed to continuously identify the range of conditions along the entire stream corridor. Meaning HDSS collects data at multiple scales including the microhabitat, reach, and segments scales. Data collection at the segment level provides a critical link between the reach and drainage basin scale. This segment-level data permits for integration among data at various scales and allows for the development of relationships vital to proper management. 

HDSS data can be used independently or in combination with previous research. Since HDSS continuously collects data, information at the microhabitat, reach, and segment levels are simultaneously collected. This allows for a simplified scaling process among these spatial scales and drainage basin data. Additionally, the segment-level data collected with HDSS data can be used to link microhabitat and drainage basin scales from other research or in cooperation with previous research as a validation tool to ensure consistency among the scales.

By utilizing the HDSS approach, you benefit by:

  • Quickly and accurately determine the problem areas along your waterway.
  • Quickly and accurately link the data from microhabitat to drainage basin scales to improve your understanding of interactions.
  • Accurately develop linkages among physical and biological conditions.
  • Develop a comprehensive understanding of the unique physical and biological characteristics within the river or stream.
  • Quickly and accurately determine physical and biological constrictions.
  • Quickly prioritize your management actions.
  • Easily review HDSS StreamView Video to address additional needs or confirmation.
  • Easily integrate HDSS data into your existing data and layers.


Modified image from Fausch et al. (2002) Landscapes to Riverscapes: Bridging the Gap between Research and Conservation of Stream Fishes. BioScience
Image From Fausch et al. (2002) Landscapes to Riverscapes: Bridging the Gap between Research and Conservation of Stream Fishes. Bioscience