Date of Award

11-30-2012

Degree Type

Report

Degree Name

Master of Natural Resources (MNR)

First Advisor

Frank Howe

Abstract

Part I of this report is focused on assessment of habitat changes on the San Rafael River after the abnormally high water year in 2011. Having habitat data and aerial imagery collected in 2010 (pre-flood) provided an opportunity to assess how a flood of this magnitude changed river habitat. In 2011 we commissioned a second aerial flight of the San Rafael River to serve as post flood imagery, then used Geographic Information Systems (GIS, ArcMap 10) to analyze river changes due to tamarisk removal and flooding. Our tamarisk removal project appears to have increased the potential for spring floods to diversify river habitat. The lack of complex habitat (pools, riffles, backwaters) is a limiting factor for native fish in the lower San Rafael River. Part I of this report also includes investigations into the importance of large woody debris (LWD) in creation of complex river habitat. Pools, riffles, and backwaters occurred more frequently within 30 m up and down stream of LWD piles (LWD buffers) compared to areas within 30 m of random points (random buffers). In addition to a greater number of pools around LWD, the pools inside LWD buffers were also significantly larger than those associated with the random buffers. The size of riffle and backwater habitat was not significantly different between the LWD buffers and the random buffers. LWD piles strongly influence the formation and distribution of complex habitat along the lower San Rafael River. Due to the importance of LWD in creating complex habitat and thermal refuge, several management options are discussed that would increase the LWD in the San Rafael River. Part I primarily covers the ecological component of this study, however the recommendations section of Part I discusses some of the policy and economic issues concerning restoration of the San Rafael River. Part II of the report will include human dimension, policy, and economic aspects of restoration efforts on the San Rafael River. Here we evaluate how water use could be impacted by further declines in native fish species and how potential listing of the ‘three species’ would affect water users in the San Rafael River Drainage. The roundtail chub (Gila robusta) has been petitioned for listing under the Endangered Species Act in the Lower Colorado Basin. If roundtail chub were listed in the Upper Colorado Basin, the San Rafael River could be listed as critical habitat for recovery of the species. Part II also consists of a literature review of the current research available on the San Rafael River. The literature review is a synthesis of past research that illustrates the importance and need for restoration of the San Rafael River. Part II also identifies future research needs, such as evaluating the reintroduction of beaver as a restoration technique. This section will also discuss the pros and cons of current and proposed management practices, as well as identify how changes in local water policy and management could benefit native fish populations of the San Rafael River. Many of the proposed management practices such as installing more efficient irrigation systems, and working with water users to coordinate release of water in the spring time, will assist in the large undertaking of providing more flows for the benefit of native fish. The economic and ecological aspects of various tamarisk control methods is discussed with costs given for the current methods of tamarisk control being used on the San Rafael River.

2-7-2014