11. Instream cover |
Greater than 50% mix of diversified habitat: presence of snags, submersed trunks, rubble, or others. |
30 to 50% mix of diversified habitat: adequate for maintenance of populations of aquatic organisms. |
10 to 30% mix of diversified habitat: habitat availability less than adequate. |
Less than 10% mix of diversified habitat: lack of habitat is obvious. |
12. Epifaunal substrate |
Well-developed riffle and run; riffle as wide as the stream and length extends twice the width of stream. |
Riffle as wide as the stream, but length is less than twice the width of stream. |
Run may be lacking; riffle not as wide as the stream and length is less than twice the width of stream. |
Nonexistent riffles or runs. |
13. Frequency of riffles |
Relatively frequent occurrence of riffles; distance between riffles divided by the width of the stream is between 5 and 7. |
Infrequent occurrence of riffles; distance between riffles divided by the width of the stream is between 7 and 15. |
Occasional riffles; habitats formed by stream bed contours; distance between riffles divided by the width of the stream is between 15 and 25. |
Generally flat water or shallow riffles; poor habitat; distance between riffles divided by the width of the stream is a ratio of >25. |
14. Types of substrate |
Pebbles are abundant mainly in the sources. |
Abundance of pebbles; common gravel. |
Stream bed consisting predominantly of gravel; presence of some pebbles. |
Stony, with pebbles, or loamy stream bed. |
15. Fine sediment deposition |
Up to 25% of the bottom covered with fine sediment. |
Between 25 and 50% of the bottom covered with fine sediment. |
Between 50 and 75% of the bottom covered with fine sediment. |
Over 75% of the bottom covered with fine sediment. |
16. Sediment deposition |
Less than 5% of the bottom affected by sediment deposition; no deposition in pools. |
Some evidence of modification of the bed mostly from increase of gravel, sand, or fine sediment; 5 to 30% of the bed affected; slight deposition in pools. |
Moderate deposition of gravel, sand, or fine sediment on the banks; 30 to 50% of the stream bed affected; moderate deposition in pools prevalent. |
Heavy deposits of fine material; increased development of the banks; over 50% of the bottom modified; pools almost absent owing to substantial sediment deposition. |
17. Channel alteration |
Channeling (rectification) or dredging absent or minimal; stream with normal pattern. |
Some channeling present, usually in areas of bridge abutments; evidence of channeling greater than past 20 years. |
New embankments present on both banks; 40 to 80% of stream reach modified. |
Banks modified; over 80% of stream reach modified. |
18. Channel flow status |
Water reaches base of both lower banks; minimal amount of channel substrate is exposed. |
Water fills more than 75% of the available channel; or less than 25% of channel substrate is exposed. |
Water fills 25 to 75% of the available channel, and/or riffle substrates are mostly exposed. |
Very little water in channel and mostly present as standing pools. |
19. Bank vegetative protection |
More than 90% of stream bank surfaces covered with native riparian vegetation, including trees, understory shrubs, and non-woody macrophytes; minimal evidence of disruption; all plants allowed to grow normally. |
70 to 90% of stream bank surfaces covered with native riparian vegetation; evident disruption but not affecting full plant growth potential to any great extent. |
50 to 70% of stream bank surfaces covered with native riparian vegetation; obvious disruption; patches of bare soil; less than one half of the potential plant stubble height remaining. |
Less than 50% of stream bank surfaces covered with native riparian vegetation; very high disruption of stream bank vegetation. |
20. Bank stability |
Stable banks; absent or minimal evidence of erosion; little potential for future problems; less than 5% of bank affected. |
Moderately stable banks; small eroded areas frequent; 5 to 30% of bank in reach presents areas of erosion. |
Moderately unstable banks; 30 to 60% of bank in reach presents eroded areas; high erosion potential during floods. |
Unstable banks; many eroded areas; frequent uncovered areas on stream bends; 60 to 100% of banks present erosional scars. |
21. Riparian vegetative zone width |
Width of riparian zone >18 m; absence of anthropogenic activities (farming, roads, etc.) |
Width of riparian zone between 12 and 18 minimal anthropogenic influence. |
Width of riparian zone between 6 and 12 m; intense anthropogenic influence. |
Width of riparian zone between <6 m; little or no riparian vegetation due to anthropogenic activities. |
22. Presence of aquatic plants |
Small aquatic macrophytes and/or mosses distributed along the stream bed. |
Aquatic macrophytes, or filamentous algae, or mosses distributed along the stream bed; substrate with periphyton. |
Filamentous algae or macrophytes on few rocks or in some pools; biofilm and abundant periphyton. |
Absence of aquatic vegetation in the stream bed or large macrophyte formations, e.g., water hyacinth. |