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Design For Fish Passage at Roadway - Stream Crossings: Synthesis Report

10 Monitoring

How to use this chapter

  • Introduction to the importance of monitoring the performance of culverts designed for fish passage
  • Learn of the three types of monitoring
  • Learn important questions to ask when establishing monitoring programs

Although much research has been done to understand the requirements of fish passage, gaps in knowledge, nuances in fish behavior, and lack of adequate hydraulic and hydrological data result in criteria that are likely quite conservative (Furniss 2006). A monitoring program will help ensure that structure impact on fish passage is more clearly understood, allowing future criteria for assessment and design to be more effective, and aiding in reducing future expenditures for fish passage (General Accounting Office 2001).

10.1 Purpose and Scope

The four types of monitoring listed in Table 10.1 can be carried out on a fish passage project (adapted from Collins 2003).

Table 10.1 Types of Monitoring (adapted from Collins 2003)
Type of Monitoring Description
Implementation Determination of whether culvert is installed as planned, providing a baseline for future monitoring.
Effectiveness Evaluation of whether a proper installation is having the desired effects.
Validation The evaluation of a model's ability to predict events or performance.
Life Cycle Evaluation of physical condition of culvert and adjacent streambed.

For the purposes of fish passage monitoring, implementation and effectiveness monitoring are the most pertinent consideration (Collins 2003). Barnard's study of stream simulation culverts in western Washington is an example of effectiveness monitoring, and has allowed a better understanding of variables (i.e. width ratio and slope ratio) leading to successful stream simulation (2003).

For fish passage installations, implementation and effectiveness monitoring protocols might be used to answer the following questions (Collins 2003):

  • Are restoration projects being carried out as proposed?
  • Are restoration projects having the intended results?
  • Are fish and other aquatic organisms responding in a positive way to the restoration treatments?

Monitoring may take place completely within a State DOT or may be the product of a multi-agency regional agreement. The latter approach would ensure consistent communications between all agencies responsible for fish passage.

10.2 Methods

Monitoring should begin with clear project goals that will allow the development of measurable parameters to allow "success" to be quantified (Committee on Restoration of Aquatic Ecosystems 1992). Ideally, monitoring might include direct observation of fish movement and utilization, but should at least focus on project compliance with design specifications such as substrate retention and the ability to maintain fish passable conditions (Furniss 2006).

Beginning with project goals in mind, parameters and field methods should be aimed at comparing current physical conditions to design performance criteria. Building upon this type of analysis, Harris (2005) developed the following criteria (Table 10.2) for fish passage installation effectiveness monitoring in California.

Table 10.2 Monitoring Questions, Parameters, Effectiveness, Criteria and Field Methods (adapted from Harris 2005)
Monitoring Question Effectiveness Criteria Parameters Field Methods
1. Is the project still functioning as designed? Fish passage restoration project is within DFG passage guidelines.
a. Is there still a sufficient jump pool depth for targeted species and life stages? Residual pool depth at downstream outlet (if culvert outlet is perched or has entry leap) If there is a jump, pool depth is appropriate for leap height. (Not required for no entry leap.) Thalweg profile through culvert plus water depths
b. Are leap heights still within jumping ability for targeted species and life stages? Leap height (residual pool water surface elevation to passage outlet) Leap height is below critical heights for targeted species and life stage. (Not applicable for no entry leap.) Thalweg profile through culvert
c. Is stream velocity in critical flow areas still within the swimming ability of the target species and life stages? Stream velocity in critical area Stream velocity is equal to or less than swimming ability of target species and life stage. Stream velocity/discharge measurements
d. Is upstream inlet of the passage area/structure still at grade or below the channel bed? Bed elevation at inlet and inlet elevation Culvert inlet matches grade of the natural channel bed. Thalweg profile through culverts
e. Is the passage area/structure still at grade? Slope Passage structure is at specific designed slope or the slope relative to the natural channel. Thalweg profile through culvert
f. Can sediment bed load still pass through the restored area? Slope (top riffle to opening), active channel width, hydraulic capacity. Passage inlet shows no signs of clogging or deposition. Thalweg profile through culverts, Cross section surveys
g. Can the structure pass the design flood discharge and meet headwater policies? Hydraulic capacity Passage passes 100-yr flows and watershed products. Cross section surveys
h. Does the passage project show signs of imminent failure? Structural integrity Structure shows no signs of collapsing. Inspection of all culvert structural elements
2 . Have channel or bank adjustments impaired the function of the passageway? Slope, head-cutting, sediment deposition Channel adjustments have not impaired passage or habitat values. Thalweg profile through culverts
3. Did the project have adverse effects on upstream or downstream habitat? Bank erosion, channel incision/head-cutting, debris accumulation or sediment deposition Passage project has not adversely affected up and downstream habitat. Thalweg profile through culverts, Cross section surveys
4. Is upstream habitat still suitable for the targeted fish species and life stages? Habitat types and quality in upstream reaches Area is still suitable for targeted species and life stages. Habitat monitoring
10.2.1 Inventory and Assessment

Inventory and assessment, as outlined in Chapter 4 is a form of effectiveness monitoring that will allow designers to gain design experience through an understanding of the impact that structures have on a stream reach and fish populations. Many design techniques, such as those described in Browning's survey of culverts in Oregon (1990), were derived from field observations of existing structures, and can continue to be modified as monitoring provides insight into the sustainability and impact of specific culvert design elements.

10.2.2 Surveying and Field Inspection

Monitoring, surveying and field inspection should focus on many of the same elements described in Chapter 4. This can include consideration of channel slope and elevation, culvert slope, crossing inlet and outlet conditions, existing bed material, and debris accumulation. Photos, benchmarks, monumented cross sections, and floodplain and terrace elevations can be useful in determining the culvert impact on the surrounding stream, and to determine if channel incision has occurred (Castro 2003). A major question to ask while in the field is - Is this culvert functioning as intended? (Furniss 2006).

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Updated: 09/22/2014

United States Department of Transportation - Federal Highway Administration