# The Biological Assessment and Rehabilitation of the World's Rivers: An Overview
## 2 Biological Assessment of Rivers
### North America
(3) For fish assemblages, stream and river length is 26% good, 22% fair, and 37% poor, varying regionally with 60% and 24% poor in the Coastal Plains and Northern Plains, respectively. Nationally, 14% of the stream and river length (ranging from 5-35% regionally) could not be assessed for fish assemblages because of the likely presence of threatened or endangered species. (4) Poor macroinvertebrate condition is nearly twice as likely in USA rivers and streams with high acidification, phosphorus, nitrogen, salinity and sedimentation levels, or low riparian vegetation cove. (5) In the West, excessive levels of nitrogen, sedimentation, and salinity were 3-4 times as likely to lead to poor macroinvertebrate condition. (6) The environmental predictors of biological metrics, and the strengths of their relationships, varied among ecoregions and between fish and macroinvertebrate assemblages. (7) Anthropogenic predictors were more important for explaining metric scores than natural variables. (8) This was also true of site-extent predictors versus catchment-extent predictors. (9) Fish and macroinvertebrate indices were weakly correlated, and (10) differed in the strength of their responses to different sets of predictors. (11) The above results support using multiple assemblages and sampling of multiple environmental predictors when conducting rigorous ecological assessments. In addition, [PERSON] et al. [234] reported that agriculture and urbanization were consistently related with lower macroinvertebrate metric scores across the conterminous USA, presumably because of the prevalence of those human influences. Although less prevalent, metal or coal mines were reported to negatively influence fish assemblages at a threshold density as low as \(<\)0.01 mine/km\({}^{2}\)[235]. The major NRSA shortcomings or gaps are: (1) not conducting the survey in the states of Alaska [236] and Hawaii or the territories of Puerto Rico, Guam, or American Samoa; (2) not surveying ephemeral or seasonally intermittent streams and rivers [237]; (3) long lag times between the field surveys and publication of the results; and (4) inadequate communication of results and implications to the USA public. Three other national ecological monitoring programs are NAWQA (National Water Quality Assessment), NEON (National Ecological Observatory Network), and LTER (Long Term Ecological Research) sites. NAWQA biological assessments has collected ecological data from 51 study units focused on monitoring toxics and assessing the effects of urbanization and agriculture on stream and river ecosystems using fish, macroinvertebrate and algal indicators. NEON has established 27 stream and river sites that are monitored twice per summer using methods adapted from NRSA. In addition to USEPA's national ecological assessments, nearly all USA states have relatively active ecological assessment programs, typically focused on point sources, or egregious diffuse sources, of pollution. Five of those states have implemented particularly rigorous ecological assessment programs, some already for four decades, based mostly on macroinvertebrates but also with fish: California [238], Iowa [239; 240], Maryland [241], Ohio (since 1979; [242]); and Oregon [243]. In Canada, the Canada Water Act [244] provides a mechanism for formal consultation and agreements with the provinces and territories, which has led to a monitoring focus on water quantity (via the Water Survey of Canada) and quality (water chemistry). However, there is no legislation that requires maintenance and assessment of biological condition in aquatic ecosystems at the national level. Instead, biomonitoring of freshwater ecosystems at the federal level is often used to support larger projects and developments (e.g., environmental assessments, Oil Sands development), areas of concern (e.g., Lake Winnipeg basin), national parks (e.g., for the freshwater component of the local ecological condition assessment) or trans-boundary rivers (e.g., Wolastoq | St. John River and Columbia River).