Nutrients, Algae and Beneficial Use Support Assessment of the Boulder River

by

John M. DeArment

B.A. James Madison University, 1990

Presented in partial fulfillment of the requirements

of the degree of Master of Science at

The University of Montana, 2003

ABSTRACT:   From 1996 to the present, the Boulder River, a tributary to the Yellowstone River near Big Timber, Montana, was listed by the state of Montana as impaired by dewatering in its lower 5 miles.  The remainder of the river has never appeared on the state’s list of impaired waters, but reports of nuisance algae blooms by local residents beginning in the early 1990’s indicated that the Boulder might be suffering from nutrient impairment, particularly in the area upstream of Natural Bridge.  In response, the Montana Department of Environmental Quality (DEQ) and the Sweet Grass Conservation District agreed to sponsor and fund this study of the Boulder River to investigate the algae bloom and nutrient concentrations in the river.  At the time, little information existed with which to determine whether the Boulder Rive supported its beneficial uses; hence the sponsors also requested that the study gather sufficient and credible data for making a use support determination.  The objectives of this study included the following: 1) provide an initial assessment of the reported algae blooms in the Boulder River and explore the possibility that human-caused nutrient sources were fueling the algae bloom; 2) gather sufficient and credible data with which to evaluate support of beneficial uses in the Boulder River; and 3) provide baseline data for comparison with future water quality studies of the river.

        Synoptic sampling for nutrients (nitrate+nitrite, total Kjeldahl nitrogen, and total phosphorous) was performed approximately monthly from August 1999 through October 2001 at sites along the river that bracketed suspected sources.  No significant human-caused sources of nutrients were detected during this study.  Moreover, instream nutrient and algal levels did not violate the only standards currently set for these parameters in Montana.  However, nutrient levels did sometimes exceed levels recommended by the EPA for this area.   In late spring of 2000 and 2001, the alga Ulothrix zonata was highly visible in isolated patches throughout the upper river above Natural Bridge.  However, Ulothrix levels did not appear to be correlated with development in the upper watershed or with nutrient concentrations.

        The Montana Department of Environmental Quality’s beneficial use support determination assessment was performed at seven locations in August 1999. The assessment consisted of a suite of chemical, biological, and physical parameters.  The weight of evidence provided by this assessment suggested that the Boulder River fully supported aquatic life and other beneficial uses in 1999; however, the river below Natural Bridge appeared to be near the threshold of minor impairment.  To maintain water quality in the Boulder Watershed, a watershed group has recently been formed.  Maintaining instream flows and protecting riparian areas from development and overgrazing are key parts of a strategy to maintain water quality in the Boulder.

TABLE OF CONTENTS

Introduction  ......................................................................................................................... 1

Study Objectives  ................................................................................................................. 2

Description of the Boulder River Drainage  ......................................................................... 3

Monitoring and Assessment Design and Method  ............................................................... 6

Results and Discussion  ...................................................................................................... 10 

       Streamflow  ................................................................................................................. 10

       Nutrients  ..................................................................................................................... 11

              Total Phosphorous  ............................................................................................... 12

              Nitrate+Nitrite Nitrogen  ...................................................................................... 13

              Total Nitrogen  ...................................................................................................... 14

       Chlorophyll a  .............................................................................................................. 14

       Other Water Chemistry  ............................................................................................... 18

       Metals in Fine Bed-Sediment  ..................................................................................... 19

       Macroinvertebrates  ..................................................................................................... 20

              Macroinvertebrate Habitat Assessment  ............................................................... 20

              Macroinvertebrate Community Assessment  ........................................................ 21

       Periphyton  ................................................................................................................... 21

       Stream Reach Assessment  .......................................................................................... 22

Conclusions  ........................................................................................................................ 24 

Recommendations  ............................................................................................................. 29

References  ......................................................................................................................... 32

Appendices

Appendix A     DEQ field forms  ....................................................................................... 62

Appendix B     Water Quality Sampling Results and Methods  ......................................... 73

Appendix C     Metals in Fine Bed Sediment Sampling Results and Methods  ................. 81

FIGURES

Figure 1.    Project Location  ......................................................................................................................................... 35

Figure 2.    Vegetation of the Boulder River Watershed  ......................................................................................... 36

Figure 3.    Geology of the Boulder River Watershed  .............................................................................................. 38

Figure 4     Major Soil Units of the Boulder River Watershed  ................................................................................ 41

Figure 5     Sampling Locations on the Boulder River  ............................................................................................. 43

Figure 6.    Boulder River Discharge at Big Timber, 1999, 2000, 2001 and Mean Discharge 1948-2001  .... 45

Figure 7.    Boulder River Total Phosphorous Concentrations, Aug 1999 – Oct 2001  ...................................... 48

Figure 8.    Boulder River Nitrate+Nitrite Concentrations, Aug 1999 – Oct 2001  .............................................. 49

Figure 9.    Boulder River Total Nitrogen Concentrations, Aug 1999 – Oct 2001  .............................................. 50

Figure 10.  Boulder River Attached Algae Standing Crop, Aug 1999  .................................................................. 51

Figure 11.  Boulder River Attached Algae Standing Crop, June 2001  ................................................................. 52

Figure 12.  Boulder River Fine Bed Sediment Copper Concentrations, Aug 1999.  ........................................... 53

Figure 13.  Boulder River Macroinvertebrate Habitat Assessment Scores, Aug 1999  ...................................... 55

Figure 14.  Boulder River Macroinvertebrate Bioassessment Scores, Aug 1999  ............................................... 56

Figure 15.  Boulder River Stream Reach Physical Assessment Scores, Aug 1999  ............................................. 59 

TABLES

Table 1.     Boulder Watershed Vegetation Types  ................................................................................................... 37

Table 2.     USGS Geologic Mapping Units in the Boulder River Watershed  ...................................................... 39

Table 3.     USGS Geologic Mapping Unit Definitions  ............................................................................................. 40

Table 4.     NRCS Soil Mapping Units in the Boulder River Watershed  ............................................................... 42

Table 5.     Sampling Locations on the Boulder River, Aug 1999 to Oct 2001  .................................................. 44

Table 6.     Boulder River streamflow at Big Timber on dates of water sampling for nutrients  ...................... 46

Table 7.     Clark Fork River Nutrient and Chlorophyll Standards  ....................................................................... 47

Table 8.     U.S. EPA Nutrient Criteria for Level III Ecoregions 16 and 15  ......................................................... 47

Table 9.     Macroinvertebrate Habitat Assessment of Riffle/Runs, Boulder River, Aug 1999  ...................... 54

Table 10.   Macroinvertebrate Habitat Assessment of Pools/Glides, Boulder River, Aug 1999  ..................... 54

Table 11.   Macroinvertebrate Community Assessment, Boulder River.  Aug 1999  ........................................ 57

Table 12.   Periphyton Community Structure.  Boulder River, Aug 1999  ........................................................... 58

Table 13.   MDEQ Stream Reach Assessment Score Breakdown for the Boulder River, Aug 1999  ............. 60

Table 14.   Boulder River Beneficial Use Support by Stream Assessment Parameter  ...................................... 61