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Based on the results of collections prior to and those of this survey, 12 families including 81 species of Ephemeroptera have been found in New Mexico. "Of the major drainage systems in the state, the Gila system is the most species rich with 48 species, followed by the Rio Grande (46), Pecos (39), Canadian (28), and San Juan (25). Eighteen New Mexico mayfly species are known exclusively from western drainages in the state (San Juan, Zuni, San Francisco, Gila) and 23 species are known exclusively from eastern drainages (essentially all drainages east of the continental divide: Dry Cimarron, Canadian, Rio Grande, Pecos)" (McCafferty et al. 1997). New Mexico is rich in mayfly species when compared to adjoining states: Arizona (9 families, 66 species); Colorado (14 families, 100 species); Texas (11 families, 92 species); and Chihuahua, Mexico (5 families, 27 species). Many species are rare, known from only one location. One of these, the large burrowing mayfly Hexagenia bilineata constitutes a new state record found during our survey only at one location, just upstream from Harkey Crossiing on the Black River (Eddy County), a tributary of the lower Pecos River. The pool habitat containing calcareous sediments is the only one of this type found, so far, in New Mexico. Objective 3. The database for contemporaneous fish collection records was completed for all sites sampled to date (154 sites). In addition, plausible presence-absence records of the historic (circa 1550), natural occurring fish fauna were compiled for these sample sites. This will facilitate comparisons of the aquatic ecoregions with the native fish faunal regions. Presence/absence data of native fish species were used to delineate fish faunal regions. The fish species faunal regions are confined generally to drainage basins, although some faunal regions span drainage boundaries. In the mountains, two faunal regions are common to the Rio Grande, Pecos, and Canadian/Arkansas River drainages, one represents depauperate headwater streams and the other represents more diverse streams. Separate faunal regions are described for mountain streams of the upper and lower Colorado River drainages. These faunal regions of the Colorado River drainage differ primarily in their native species for the genera Oncorhynchus, Catostomus, and Rhinichthys. From foothills to lowlands, a single fish species faunal region in each drainage is sufficient to describe the assemblages in the upper and lower Colorado River and the Canadian/Arkansas River drainages. Within the Rio Grande and Pecos River drainages foothill to lowland sites on the river mainstems are divided into two fish faunal regions, a middle elevation transition zone and a lowland mainstem zone. Upland to lowland tributaries to the Pecos River are recognized as a separate fish faunal region. Fish in two contemporary endorheic basins form the remaining faunal regions, i.e., lowland springs of the Tularosa Basin and the Mimbres River Basin. Fish faunal regions have also been delineated for fish genera and for an ecological classification that captures differences in reproduction. In general, fish faunal regions bear little resemblance to aquatic ecoregions in the state. Fish species richness in New Mexico river drainages is positively correlated with drainage basin area. A manuscript of these findings is appended to this report (Appendix 2). The co-authors of this report intend to publish these findings in a peer reviewed scientific journal. 5