4.1  Introduction

This chapter describes the stream site inventory for fish and fish habitat. Use the procedures and standards described in this document to conduct a reconnaissance field program. This will ensure collection of good quality data and proper interpretation of results. Clearly document any unavoidable departures in methodology. Strict adherence to standards (e.g., units of measurement) must not vary. However, if required, there can be some flexibility in the procedures used to collect data (e.g., fish sampling methodology).

4.1.1  Field Inventory

The project leader must adopt and follow a standardized field plan to maximize the efficiency of the time spent in the field. The plan should include contingency options that address possible field conditions (e.g., survey lakes first if streams are high). Every crew member must know their role and the sequence of the sampling activities. Project timing must take into account that biophysical information is to be collected at the lowest stream flows. To minimize disturbance to fish and water quality, complete water and fish sampling before the physical inventory.

The field portion of the Reconnaissance Fish and Fish Habitat Inventory is comprised of:

1. channel measurements;
2. cover inventory;
3. features identification;
4. description of water conditions;
5. morphology characterization;
6. habitat quality assessment;
7. wildlife observations;
8. photography; and
9. fish sampling.

For wetland reaches, the minimum information required is site referencing, cover (cover estimates), water characteristics (temperature, pH, conductivity, turbidity), photos, and habitat quality characterization. Other data fields on the site card should be completed if applicable.

4.2  Standard Data Collection and Procedures

4.2.1  Site Card

Use the site card to capture data collected in the field. As part of your pre-field site referencing, transcribe reach referencing information to the site card. See Site Card Field Guide, RIC.

4.2.2  Site Referencing and Measurements in the Field

A site is defined as a section (segment) of a stream or wetland reach where the field sampling is conducted. Site referencing includes:

• Site UTM: the UTM coordinates of the downstream end of the site;
• Site length: the total length of the field site as measured in the field (by metre tape, hip-chain, etc.) along the stream course (thalweg). The site must be at least the greater of 100 m or 10 times the bankfull width (W_b). In some instances, the site length may be increased to adequately capture habitat sequences, etc. (e.g., when pool or riffle units are longer than 100 m or 10 W_b).
• Site number: a unique three-digit number assigned to all sites within a project.

Reference additional header information on the site card as stated in Chapter 3, Lake Inventory Standards and Procedures.

4.2.3  Channel

4.2.3.1  Channel width

The channel width (also called bankfull width [W_b]) is the width of the bankfull flood stage of the stream channel. A number of criteria can be used to determine the W_b in the field (Fish-stream Identification Guidebook, Channel Assessment Procedure Field Guidebook, Forest Practices Code). Use only those criteria relevant to the particular field site. The following should be considered:

• a change in vegetation (>2 years old) from bare ground, with no trees, to vegetated ground with trees, from no moss to moss covered ground, or from bare ground to grass-covered ground, particularly in range lands (i.e., where rooted, terrestrial vegetation begins);
• a topographic break from vertical to flat floodplain;
• a topographic break from steep bank to more gentle slope;
• the highest elevation below which no fine woody debris (needles, leaves, cones or seeds) occurs; and
• a change in texture of deposited sediment (e.g., from clay to sand, or sand to pebbles, or boulders to pebbles).

To measure the width of a channel stream:

• Include all unvegetated gravel bars in the measurement (see Figure 4.1). These generally show signs of recent scouring or deposition.
• Where multiple channels are separated by one or more vegetated islands, the width is the sum of all the separate channel widths. The islands are excluded from the width measurement.
• Measure the widths at a minimum of six sites, taken at equally spaced intervals. The six channel/wetted widths can be measured using a spacing of the bankfull width (from the first measurement), or they can be equally spaced over the site. For example, for a stream with a bankfull width of 4 m, the measurements could be taken every 4 m or every 20 m (six measurements over the 100 m site length), but the latter should be used as it is more representative. For small streams it is suggested the measurements be taken equally spaced over the site; for larger streams, choose the method that is most representative of the site.
• Generally, do not take stream widths near stream crossings, unusually wide or narrow areas (e.g., impoundments), or disturbances (see the Fish-stream Identification Guidebook, Forest Practices Code). However, outline width estimates for these areas in the comments section of the site card.

Figure 4.1. Measuring channel bankfull widths.

4.2.3.2  Wetted width

The "wetted width" is the width of the wetted portion of the stream channel. If multiple channels occur, then the separate widths should be added together, as illustrated in Figure 4.1 (also refer to Riparian Management Area Guidebook, Forest Practices Code, and Fish-stream Identification Guidebook, Forest Practices Code. For wetted width spacing intervals, use the same procedure as for channel width (see 4.2.3.1).

4.2.3.3  Residual pool depth

The residual pool depth is the difference between the maximum pool depth and the riffle crest depth (or pool outlet depth). Record residual pool depths for a minimum sub-sample of six pools. Make every attempt to select representative pools for measurement while also recording depths for the deepest pools encountered within the site.

4.2.3.4  Gradient

Gradient is the slope or rate of vertical drop per unit of land of the channel bed. Measure gradient along the longest sighting within the site. This section should be at least 60 m long and preferably longer. However, sighting distances along small streams with thick riparian vegetation may be 30 m or less. Where visibility is restricted, take sightings in both upstream and downstream directions from a given point to maximize the length of stream used to calculate gradient. Take at least two gradient measurements at the site. The use of an Abney level or a more accurate measuring device is suggested where accurate measurements are required, such as where gradients are less than 3% and where gradients fall between 18 and 22% (20% is a critical Forest Practices Code gradient break). Methods used for measurements must be recorded on the respective site card.

4.2.3.5  Depth at channel bankfull

Depth at channel bankfull is the depth of the channel at bankfull flow. Measure the depth of the bankfull discharge, with a calibrated rod to the nearest 10%. Depending upon the channel morphology, measure this depth at a step-pool break (immediately upstream of a step), or at a riffle-pool crest (immediately upstream of a riffle) (see Figure 4.2).

Figure 4.2. Locating depth measurement.

4.2.3.6  Stage

This is the stage of the current discharge. Stream discharge is the amount of water passing through the channel at the time of survey. Visually estimate water height as a percentage of W_b depth at the same site where W_b was determined. Classify stage as (L) low flow: 0-30% of W_b depth; (M) medium flow: 30-90% of W_b depth; or (H) high flow: >90% W_b depth.

1. Observe the amount of water in the channel in relation to the bankfull depth.
2. Look for the low flow indicators including

• Distinct sequence of riffles and pools or steps and pools.
• High bank tops.
• Wetted width significantly smaller than channel width.
• Dry, unvegetated channel bars.
• Debris and jam pile ups well above water surface.

3. Look for high flow indicators including:

• Distinction between riffles and pools or steps and pools is difficult to determine.
• Water level at or over bank tops.
• Wetted width similar to or greater than channel width.
• No bars or bank sides visible.
• Debris movement in channel.
• Submerged riparian vegetation.
• Flood channels full of water.