A typical, but difficult task for managers is knowing and understanding the scope of problems within a river or stream. This includes what are the problems, where they are located, as well as their potential interactions throughout the entire area of influence.

Trutta has developed the High Definition Stream Survey – Stream Corridor Assessment (HDSS-SCA), a rapid method to determine the condition of a stream to help identify the areas of greatest need of restoration and/or conservation. The HDSS-SCA is based on the Maryland Stream Corridor Assessment methodology (Yetman 2001). This assessment provides continuous 1-meter longitudinal resolution of the conditions present in a river or stream corridor. The results of the HDSS-SCA allows managers and planners to make informed decisions, supported by well documented evidence, on actions that directly influence their desired outcomes.

The HDSS-SCA framework consists of six fundamental elements: streambed, right and left streambank, right and left riparian area, and discrete features. This framework is similar to Platts et al. (1983) definition of the riparian zone, with the exception of discrete features. Continuous data include the streambed, left and right streambanks, and left and right riparian areas while discrete features are point locations of anthropogenic or environmental importance. When combined, these six elements define the location, extent, and condition of issues within the stream corridor to aid in planning and effective management. Additionally, each element can be used independently to identify and target specific management actions. From the assessment, you will have a prioritization of management actions to improve or protect the river and its habitats.

The HDSS-SCA will document location, extent, condition, modifications and correctability of issues throughout the river system following a standardized protocol so that all of the results can be compared among different survey areas. These classifications will highlight any areas of concern and serve as a baseline for comparison with future surveys.

By applying the HDSS approach, you benefit by:

  • Quickly and accurately determine the extent and location of problem areas.
  • Identifying how your streambanks, streambed, and riparian zones are functioning.
  • Identifying the location and severity of manmade and natural point features.
  • Identifying the overall condition of your stream corridor.
  • Quickly prioritizing your best management actions to improve stream function and condition.

Platts, W.S., W.F. Megahan, G.W. Minshall. 1983. Methods for evaluating stream, riparian, and biotic conditions. Gen. Tech. Rep. INT-138. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station. 70p.

Yetman, Kenneth T. September 2001. Stream Corridor Assessment Survey, Watershed Restoration Division Chesapeake & Coastal Watershed Services Maryland Dept. of Natural Resources Annapolis, MD.


Suitability Overview

Suitability is the ability of the habitat to support a candidate (e.g., species, activity, item) over a period of time. Suitability modeling is a statistical method for predicting the suitability of a habitat for a candidate while suitability models are created to qualify, compare, and rank candidate locations. These models are created using a selected set of criteria required by the candidate to persist. When all the criteria are present at their full potential then a habitat is considered highly suitable, however, when the criteria are not present at their full potential, or partially, then the suitability is decreased. Suitability is generally viewed as a scale from most suitable to not suitable.

Species Habitat Suitability

Generally, habitat can be viewed as the home for stream animals. A healthy stream that can support a wide range of fish and invertebrates usually has a mix of different habitat types that provide the animals with their preferred living conditions.

HDSS StreamView video can be reviewed in a dashboard format to delineate habitat type (riffle, runs, and pools), substrate, substrate embeddedness, water depth, instream cover and other habitat variables. To document overall habitat suitability, scores for individual parameters can be combined to determine overall habitat condition and are used to create a habitat suitability model for species of concern in the survey area. 

HDSS documents changes to instream habitat conditions and makes comparison of poor and excellent instream habitats obvious. The variance in habitat conditions is well documented with longitudinal surveys.

We have created habitat suitability models for numerous fish (rainbow and brown trout, muskellunge, largemouth and smallmouth bass, as well as several small gobies and darters) and invertebrates (mussels, crayfish and shrimp). Habitat suitability models for the different species can be based on published criteria, survey results or professional opinion. All work well with the HDSS modeling approach.

Restoration Suitability

Improving the amount of habitat within a stream is the general premise behind habitat restoration. However, knowing where to implement restoration activities that meet all of the management objectives is not always clear. Therefore, restoration suitability modeling is used to identify the best locations to implement habitat restoration activities.

Trutta has experience with developing restoration suitability models. These models often focus on criteria such as ecological uplift; however, additional criteria such as cost, accessibility, and topography are added since money is often a limited resource. For example, these models have been successfully used by State and non-governmental agencies to economically increase fish habitat that is easily accessible to anglers therefore providing more successful angling opportunities.

Infrastructure Suitability

Knowing the best location, as well as any other suitable locations, to successfully install a multimillion-dollar infrastructure project is critical. Here at Trutta we have extensive experience developing suitability models for the placement of infrastructure such as water intakes in riverine and reservoir environments. These models are developed using criteria (e.g., depth, substrate type, water velocity, bank topography, and distance to major road) provided by the clients to ensure appropriate site selection as well as alternative locations.

Recreational Use Suitability

As public use of waterways increases, managers are continually looking to improve the recreational experience within the waterways they manage. Whether it be swimming, boating, wading, fishing, etc. managers need to understand the distribution and extent conditions suitable for these activities. Suitability models can be used to quantify the distribution and extent of conditions suitable for these activities throughout the entire stream.

At Trutta we have developed multiple suitability models addressing the needs of recreational users. These recreational needs include swimming, wading, boating, and fishing. Local, state, and federal agencies have utilized these models to manage rivers and streams within their jurisdictions.


Trutta’s HDSS can be used to document the occurrence and extent of vegetation observed during the survey. Vegetation can include riparian, emergent aquatic, or submerged aquatic vegetation. The vegetation can be native or introduced species depending on the needs of the assessment. For submerged aquatic vegetation (SAV), the longitudinal HDSS track provides underwater video (1), down-looking sonar (2) and side-scan sonar (3) which can be used to detect the presence of SAV as shown in the image below.

To better understand the extent of the cross-sectional area colonized by SAV, multiple methods can be used. Multiple boats can provide parallel survey tracks to better estimate the cross-sectional coverage. The front video can be used to determine the amount of river surface area receiving adequate sunlight for SAV to grow. This can be done by documenting the amount of water shaded by emergent aquatic vegetation or by riparian trees. Cross-sectional transects could also be used to determine the proportion of the transect with SAV present.

As with determination of habitat suitability for animal species, variables such as habitat type (riffle, runs, and pools), substrate, percent open water, water depth, other habitat variables can be scored and combined to create a habitat suitability model for SAV species of concern in the survey area. The suitability model results can be used to document the potential amount and distribution of habitat for SAV throughout the river system. This result could be compared to the observed distribution of SAV to determine the amount of suitable SAV habitat currently occupied.

Overall, HDSS is a fast and effective approach to documenting the location and extent of SAV in river systems.


Limited by water clarity and depth, substrate is one of the most difficult habitat parameters to describe accurately and consistently. However, documenting the type and distribution of substrate throughout a river or stream is critical in describing what habitats are available and how they may be improved.

The HDSS method delivers a powerful solution to this problem. HDSS data provides accurate and consistent documentation of substrate type and distribution along your river or stream. Knowing what substrate types are present and their distribution allows you to optimize management actions in your entire river or stream.

By applying the HDSS approach, you benefit by:

  • Quickly and accurately determine the amount and distribution of substrate types within your river or stream
  • Identifying major areas of degradation and aggregation
  • Identifying substrates of interest for further surveys.
  • Identifying substrates that may hold species of interest for further surveys.
  • Identifying substrates that would provide suitable habitat with appropriate restoration efforts.
  • Optimizing substrate analysis for suitability model development.
  • Identifying major and minor locations that are influencing the substrate composition along the river or stream
  • Quickly prioritize your management needs based on known substrates.


Abandoned mine lands (AMLs) are those lands, waters, and surrounding watersheds where extraction, beneficiation, or processing of ores and minerals has occurred. Abandoned mine lands include areas where mining or processing activity is temporarily inactive. Past mining activities in these areas have led to environmental issues such as water quality degradation and sedimentation. The geographic scope of these projects can often be defined by watersheds and is often overwhelming when prioritizing mitigation activities.

Trutta has the experience necessary to provide the data required to develop an effective mitigation and remediation plan. Using the HDSS methodology Trutta will document physical and biological conditions throughout your entire sampling area. This typically includes a water quality assessment at all confluences and points of interest, along with our Stream Corridor Assessment. These assessments allow for a complete documentation of current conditions within the sampling area and provide the data necessary to prioritize sites of concerns, hot spots, and other major factors contributing to water quality degradation. This approach works for active and abandoned mine lands.

Trutta’s HDSS Assessment benefits you by:

  • Documenting Baseline Conditions,
  • Prioritizing very poor water quality and heavily impacted habitat,
  • Comparing past reclamation practices and results, and
  • Monitoring current and future projects.