Streams of Montana’s Milk River Basin
Physical, Chemical and Biological Characteristics
by
John D. Lhotak
B.S., Northern Michigan University, 1998
presented in partial fulfillment
of the requirements for a degree of
Master of Science
The University of Montana
May 2004
ABSTRACT: The Milk River Basin flows through northern Montana’s Northwest Glaciated Plains. Little information existed on the streams of this basin, hence to develop water quality criteria for the area, key physical, chemical and biological characteristics of ten tributaries of the Milk River were studied in the summer of 2001.
Water samples were taken in June, August and September of 2001 and analyzed for nutrients and metals. Benthic and water column algae samples were taken at the same time and analyzed for chlorophyll a and ash free dry weight. Macroinvertebrates were collected once in June. In addition to water quality sampling, riparian corridor morphology was measured, and the condition of the riparian vegetation was assessed. Also, basin wide attributes of soil and land cover were analyzed using GIS databases.
The summer of 2001 was the fourth year of drought in eastern Montana, and observations of stream characteristics should be interpreted with that in mind. By the end of the summer, four of the ten study reaches were flowing at a rate of less than 1 cfs and the other six streams had stopped flowing. All study reaches had high concentrations of phosphorus relative to nitrogen and were concluded to be nitrogen-limited. None of the study reaches exceeded the standard set to avoid nuisance algae levels in the Clark Fork River in western Montana. No study reaches violated standards for metals.
The original intent of the study was to contrast 5 highly impacted study reaches and 5 relatively un-impacted reference reaches; but almost all the study reaches had substantial impacts and differed in many characteristics. Therefore, instead of classifying the reaches as reference sites or impacted sites, study sites were clustered into similar groups based on attributes of the study reach or its basin. The least impacted examples in each of these groupings may be the best reference examples available, despite their impacts.
Because of the severe drought conditions, setting water quality standards should be delayed until additional data are collected in wetter and average flow years.
Table of Contents
Study Purpose
Milk River Basin .
Site Selection
Field Assessments – Timing and parameters assessed
Research on Available Watershed and Stream Information
Watershed Soil Assessment
Watershed Land Cover
Site layout
Physical / Morphological Characteristics
Rosgen Classification of stream channels at study sites
Natural Resource Conservation Service Riparian Assessment
Riparian Community Classification
Water Sample Collection
Algae Sampling
Lab Analysis of Water Samples and Algae Samples
Watershed and Site Descriptions
NRCS Assessment
Watershed Soils Analysis
Stream Flow
Stream Water Chemistry
In-stream Nutrients
In-stream Benthic Chlorophyll
Aquatic Macroinvertebrates
Nutrients and Algae
Watershed & stream attributes used to group study sites
Grouping based on multiple factors
Appendix A: Lower Milk River basin tributary study sites
Appendix B: Description of Soils Attributes
Appendix C: Water Analysis methods in Milk River Basin tributary study
Appendix D: Milk River tributaries study site characteristics
Appendix E: Plant Lists of study reaches in the Lower Milk River Basin, MT
Appendix F: Land Cover and Soil Characteristics of Lower Milk River Watersheds
Appendix G: Lower Milk River Tributaries Water Chemistry
Appendix H: Nutrient Levels in Lower Milk River Tributaries
Appendix I: Stream Algal Levels in Lower Milk River Tributaries
Appendix J: Example Field Forms
The prairie streams of Montana’s Milk River Basin have never received the scientific attention given to the streams of Montana’s western mountains. Hence the natural behavior of these prairie streams is poorly understood, making it difficult to evaluate their condition. To determine the degree of degradation of these streams, we need some idea of their pristine structure and function. However, most of the streams in the basin are thought to be greatly altered by grazing, diversions and damming. Consequently few examples of pristine streams remain in the basin.
Many streams in the Milk River basin are considered to be impaired, that is, not supporting fully their beneficial uses. The Montana Department of Environmental Quality separates beneficial uses into three broad categories, recreation, aquatic life and water supply (MDEQ 2004).
Recreation involves activities that involve physical contact with the water such as swimming or boating. Aquatic life beneficial use include plants and animals that are the basis of a healthy ecosystem including waterfowl and fur bearing animals. Although fish are an aquatic life they are listed as their own beneficial use due to their economic and recreational importance. The beneficial use for water supply includes municipal, agricultural, industrial and domestic uses. Bates, et al. (1993) also discusses the beneficial uses of water in the western U.S. They talk about the importance of water as a source of spiritual and community identity, the importance to navigation, importance to agriculture and settling the west, and water as an engine for industry.
Section 303(d) of the Clean Water Act states that a water quality restoration plan, a total maximum daily load (TMDL), be developed for impaired streams by the Environmental Protection Agency, the states and tribal authorities. Also, the Montana Department of Environmental Quality wants to improve and expand the tools it uses to assess beneficial use support in these streams. The intent of this study was to: 1) characterize key physical, chemical and biological attributes of Milk River tributary streams; 2) attempt to determine which streams were least impacted; and 3) use their structure and function to develop criteria for healthy functioning and full beneficial use support. Because the streams vary widely in character, this study also attempted to group the streams based on key common factors.
This study assembled new and existing information on tributaries in the Milk River Basin to assist in the development of physical, chemical and biological criteria for the Milk River Basin. Specifically, this study provides physical, chemical and biological information needed to classify streams into similar groups and to characterize their condition and ability to support aquatic life. The information gathered will also be useful in the development of water quality restoration plans (or Total Maximum Daily Loads) required by the Clean Water Act.
Figure 1 – The Milk River Basin in the U.S. and Canada.