1. Using Bugs and GIS to Assess and Manage Watershed Health
Jennifer Thompson
The University of Texas at Austin
November 18, 2004

2. What are benthic macroinvertebrates?
Benthic = bottom-dwelling
Invertebrates = no backbone
Macro =visible to unaided eye

3. Why study benthic macroinvertebrates?
Sensitive to physical and chemical changes in their environment
Reflect conditions for a duration of time
Interact with both sediment and water
Don’t move or swim away
Easy to collect
Relatively inexpensive to monitor

4. Water Quality Parameters specific to Bug Abundance and Diversity
Temp
Conductivity
TSS
Flow
Nitrate as N
Dissolved Oxygen

5. Metrics and Biological Indices
3 taxa groups: Pollution- intolerant, pollution-intermediate, and pollution- tolerant organisms
EPT index
Hilsenhoff Index
% community as relates to trophic structure
Aquatic Life Use

6. Aquatic Macro-invertebrate Identification Key7
Shrimp 5
Predacious
Diving Beetle
Adult
Larvae
Scavenger
Beetle
Whirligig Beetle
Biting Midge Larvae 4
Seed Shrimp
Copepod
Yabbie
Hydra
Freshwater Mussel
Scud
Water Strider
Freshwater Slater
TOLERANT
Black Fly Larvae
Mosquito
Pupae
Back Swimmer
Water Boatman
Soldier Fly Larvae
Leech
Aquatic Macro-invertebrate Identification Key
Here are the most common aquatic macro-invertebrates that will be found in the Adelaide region. Tick the spaces next to the numbers to indicate which invertebrates you have found in your samples. The number indicates the sensitivity of the invertebrate, the higher the number, the more sensitive to pollution it is.
Also tick the invertebrates that you find on the ‘Record Sheet’ so you can determine the
stream pollution index.
VERY SENSITIVE
Mayfly Nymph 8
Stonefly Nymph 9 10
Riffle Beetle
Adult
Larvae
Water
Measurer
Water Scorpion
SENSITIVE
Damselfly Nymph 6
Caddisfly Larvae 7
Dragonfly Nymph
Crane Fly Larvae
Water Flea
Freshwater Crab
Water Mite
Non-Biting Midge Larvae 3
Flatworm
Segmented Worm 1 2
Springtail
Water Spider
Round Worm
VERY
TOLERANT
Snail

7. Importance to Watershed Managers and Regulators
Identify areas of concern
Focus monitoring efforts
Track success of remediation efforts

8. Focus: Colorado River Basin
22,200 square miles
Total basin inflow: 10,738,000 acre-feet
Total basin outflow: 1993: 9,097,000 acre-feet
Irrigated acreage, 1992: 958,000 acres
Water quality: typically satisfactory
Primary data source:
TCEQ TRACS and Surface Water quality databases

9. Objectives
Provide a spatial representation of monitoring sites and bug and water quality data using different biological indices for bugs
Provide a temporal representation of data from
Compare biological integrity with state criteria (screening and water quality standards) and evaluate how the Colorado River Basin measures in comparison
Determine what impact urban development has on health of streams

10. Problem:
Only 67 bug data entries between 1996 and 2003 for the Colorado River Basin

11. City of Austin- An example of a comprehensive dataset and the Power of GIS
> 1,000 bug data points from ’93-’03
>24,000 water quality data points from ’93-’03
More powerful indices used to prioritize subwatersheds for addressing CIP projects, monitoring programs, and planning in general (e.g. Ecological Integrity Index)
More in-depth parameters taken at time of sampling (e.g. flow)

12. Ecological Integrity Index (EII)
Composed of 6 sub-indices: water quality, sediment quality, contact recreation, habitat quality, and aquatic life
Assign a score for each EII site or watershed
Scores range from (very bad to excellent)

13. City of Austin Watershed Health

14. City of Austin Watershed Health

15. What’s next?
Spatially represent changes in indices or scores over time
Use linear referencing to assign addresses to streams and creeks
Depending on frequency of data, use Time Series to show water quality changes over time
Overly land-use coverages to determine if urban impacts exist
Statistical analyses with flow
Compare water quality to state screening levels and criteria