Evaluation of Rangeland Stream Condition and Recovery Using Physical and Biological Assessments of Nonpoint Source PollutionEPA Grant Number: R823487
Title: Evaluation of Rangeland Stream Condition and Recovery Using Physical and Biological Assessments of Nonpoint Source Pollution
Investigators: Herbst, David B.
Current Investigators: Herbst, David B. , Knapp, Roland A.
Institution: University of California - Santa Barbara
EPA Project Officer: Hahn, Intaek
Project Period: September 1, 1995 through August 31, 1998
Project Amount: $249,647
RFA: Exploratory Research - Environmental Biology (1995) RFA Text | Recipients Lists
Research Category: Biology/Life Sciences , Health , Ecosystems
Description:Overgrazing by livestock may result in the loss of riparian vegetation and often leads to unstable streambanks and widespread erosion and sediment release into waterways. This type of nonpoint source pollution associated with grazing has been especially problematic for establishing contamination effects and limits. The health of streams in the Great Basin is of concern because of small size, limited protective cover, and prolonged exposure to grazing. Flowing water in the arid desert is a vital natural resource for wildlife of all kinds and excessive sedimentation in channels can choke aquatic life. Though rangeland streams have received much of the impact from grazing, little is known of effects on aquatic life uses of these habitats. Proper management of rangeland streams has been impeded by a lack of knowledge of how in-stream ecological values of water quality are affected. The specific aim of the project is to provide a biological basis for establishing standards and regulatory criteria for nonpoint source pollution impacts related to livestock grazing in rangeland watershed stream ecosystems.
Recent advances in the technology of stream ecosystem monitoring provide a tool that may help ascertain changes in water quality and habitat health caused by nonpoint source pollution. Bioassessment is a technique that uses aquatic insects and other invertebrates as indicators of pollution. Using differences in pollution tolerance and functional roles in the ecosystem, changes in the types of organisms found can be used to monitor the extent of impacts and/or habitat recovery. In order to apply the technology of bioassessment to grazing problems, this study will develop: (1) reference stream standards, (2) a baseline for trend comparisons in invertebrate communities exposed to varied grazing management practices, and (3) a database on sediment-polluted streams that can be used to analyze invertebrate associations and establish a tolerance scoring system for indicator fauna specific to grazing-related impacts. The focus of this study is to apply bioassessment to identifying nonpoint source grazing pollution problems and compare this system with traditional monitoring methods that have relied on external stream features such as channel geomorphology and riparian vegetation.
The study currently includes over 50 stream reaches on public and private land, selected to examine ungrazed reference streams, streams exposed to varied levels of grazing pressure, streams managed for recovery by removals of livestock from allotments, by reduced time or density of livestock grazing, by the presence of fenced exclosures and for which management is anticipated because of poor conditions. The varied age of different grazing practices over these sites will permit comparison of management trends. The database obtained will be analyzed using multivariate ordination and correlation techniques and statistical comparisons of grazed-ungrazed pairs on fenced exclosures. Results of this research will help define the beneficial uses of water for aquatic life and find application in rangeland stream resource management.