How frequently did ammonia concentrations exceed the U.S. Environmental Protection Agency’s (USEPA) numeric criteria for protection of aquatic life?
Concentrations of ammonia in streams seldom exceeded USEPA numeric criteria set to protect aquatic life. Specifically, concentrations exceeded the acute criteria in only 33 samples at 7 streams, from among about 24,000 samples collected from 499 streams. Concentrations exceeded the chronic criteria in 139 samples from 22 sites. The acute and chronic criteria generally were exceeded in streams in the semi-arid west draining watersheds with urban and mixed land uses. Many of these streams also receive treated effluent from wastewater treatment facilities. Few agricultural sites (out of 135 sites sampled) had concentrations above acute (1 site) or chronic (5 sites) criteria, despite relatively large fertilizer and manure sources.
Related Questions
- Can an agency change the timing of the procurement process, the evaluation criteria, or the process itself at any stage during the procurement process?
- Where can I find information on the U.S. Environmental Protection Agency’s (USEPA) recommended ecoregional nutrient criteria?
- What criteria must a hosting agency possess?
