RSRA, or Rapid Stream-Riparian Assessment, is a tool to quickly assess ecosystem health. The RSRA was developed and intended for medium gradient, medium-sized streams, ie cold-water fisheries on the Colorado Plateau. It is conceptualized as a stratified sample: Stream>Hydrologic Reach>Study Reach>Sample Transects>Indicators.
The 25 "indicators" are used as clues or warning signals to trigger further investigation. The indicators are grouped into 5 categories: the (equally weighted) categories are: 1) Water Quality, 2) Hydrogeomorphology, 3) Fish Aquatic Habitat, 4) Riparian Vegetation, 5) Terrestrial Wildlife Habitat, each of which contains 2 to 7 indicators.
The RSRA is dependent on identifying and understanding hydrogeomorphic context, as each indicator is rated from 1 (completely impacted, no value for wildlife) to 5 (absence of impact from humans). In order to adapt the protocol to differing streams, rather than categorize, the assessment's authors urge the user to only use indicators that are hydrogeomorphically consistent. The philosophy is to imagine the stream as unimpacted (or actually find a nearby Reference Reach) to compare the actual stream to the possible. This philosophy can lead to problems. For example, at Little Ash Creek we decided to ignore the historic floodplane, and base our work for Indicator #3 Floodplain Connection and Unundation on the actual flow regime, not the benches of old Gooding willow that are now campgrounds 5, 10, or 15 feet above the channel and its new braided floodplane. This contradicts the approach taken at Clearwater creek, where the new braided floodplane was considered bankfull, and the high campground terrace was considered the floodplane. Has the campground ever been flooded? Inconsistent assessment of indicators in the field is a problem, but the challenge is to be accurate as well as consistent.
It is also the hope of the authors that the protocol w0uld not be used to compare dissimilar systems (e.g. a high gradient stream to a low gradient stream). Instead, the number values serve to highlight individual stressors/indicators, rather than simplifying all systems into a high/middle/low value health hierarchy. This could be a problem for the way the methodology is currently implemented.
The RSRA is geared toward understanding and assessing wildlife habitat. For example, Indicator 5: Hydraulic Habitat Diversity teaches users to see types of animal habitat, or the world as animals see it. Wildlife need habitat diversity, and disturbed systems are usually simplified to point that certain animals can no longer survive there. So, the criterion for these features is: do they provide unique habitat, without which, a species or host of species would not occur or persist? Some example riparian habitat types include:
sidewater or edgewater : squaw fish habitat, back eddy oxygenated, but slower flow water striders, water bugs. not big enough to be lateral pool because isn't beaver habitat.
lateral pool: builds up a bar between main channel, deep(bigmouth bass, beaver colonize), deep enough to provide cover from predators
slackwater or backwater: water not being flushed, oxygen levels go down, chemistry changes, mosquito can develop, fish can't live here.
high velocity riffles: create oxygenated water. fish eggs require high oxygen, and riffles are usually cobble-floored (cobble is a better substrate for eggs than fine sediments)
low velocity riffle: rolling wave doesn't break
scour pool: focussed flow creates deep water, cover
side channel: must be active, must be connected both upstream and downstream