Data Collection Procedures
Examine Iowa Department of Transportation
(IDOT) maps for target streams and determine all practical access
points. IDOT maps are available by county by calling (515) 239-1282.
For large streams, space access areas no more than 5 miles apart;
for medium streams, no more than 3; and for small streams, allow
no more than 2 miles separation. Determine the most efficient
driving route. Clearly mark the sites to be surveyed on the map.
Before collecting the data, record your name, the date, and stream name on the data sheet. Recording the exact location at which you are collecting data is essential. Provide a description of the access area (e.g. Hwy. 30 bridge south of Ames, IA.) on the data sheet. Document the site location by marking it on the map.
If possible, take stream measurements from a data collection point at least 100 meters (about a football field length) from the access point to minimize its effect on stream characteristics (EPA 1997). Indicate on the data sheet if the data is collected upstream or downstream from the access point as well as the distance.
While proceeding to the data collection point (100 meters upstream or downstream from the access), complete a visual survey of stream banks and shallow water for mussel shell material and other aquatic animals (fish, crayfish and snails) and plants (algae, duckweed, and pondweed). Complete the aquatic plant and aquatic animal sections on the data sheet.
At the data collection point make the following measurements:
1. Stream width: Measure stream channel width in meters.
2. Water depth: Measure the depth (in cm) mid-channel of the stream.
3. Stream Flow: Research indicates 0.3 m/sec is a suitable stream velocity value for distinguishing between fast and slow conditions (Plafkin et al. 1989). Calculate the average velocity of the stream and indicate on the data sheet whether the stream flow is fast or slow. Instructions for measuring stream velocity are in Appendix A.
4. Water Clarity: In shallow streams, water clarity can be measured visually. If the streambottom is visible, water clarity is high. In deeper streams, clarity can be measured using a secchi disk, a round 20-cm diameter disk that is painted in black and white quadrants. Water clarity is high when secchi depth is greater than 60% of the water depth, moderate when between 30-60% of the water depth and low when less than 30% of the measured water depth. Instructions for using a secchi disk are located in Appendix A.
5. Substrate type: Evaluate substrate type (grab a handful!)
at 5 random places at the data collection point. Indicate on the
data sheet the dominant substrate type based on the following
categories:
Boulder (< 256 mm or 7")
Cobble (64-256 mm or 2"-7")
Gravel (2-64 mm or 0.05"-2")
Sand (0.06-2 mm - gritty)
Silt (0.004-0.06 mm)
Clay (<0.0004mm)
6. Bank vegetation: The absence or presence of bank vegetation indicates the relative stability of a stream bank. Streams banks with little or no vegetation are usually more susceptible to bank erosion which adversely influences water quality. Assess the bank vegetation present on the right and left banks as absent or present.
7. Riparian zone: Land-use adjacent to the stream influences stream habitat and water quality. Assess the land-use and/or vegetation in the areas above the right and left banks. Indicate the most dominant feature observed.
8. Additional Notes: Record miscellaneous observations important to the assessing the habitat conditions of the stream reach.