Continuous Instream Monitoring

Statistical trend tests can be used to detect trends and evaluate rates of change, but do not provide insight in attributing a trend to a particular cause.

Land use and land cover changes within a watershed are some of the most likely causes for changes in water quality.  Watersheds that are largely forested, such as Baker Run pictured at right, typically exhibit healthy water quality while developed, urban, and agricultural watersheds (shown below) typically reflect degraded water quality.

 A one-way ANOVA (analysis of variance) was used to determine if stations with increasing trends, decreasing trends, or no trend had significantly different (α≤0.05) changes in land use.  The resulting data showed no significant difference between stations with increasing, decreasing, and no water quality trend.

There are five CIM stations with increasing water temperature trends and one with a decreasing water temperature trend. As temperature increases in a stream, DO levels decrease; DO levels below 5 mg/l can have adverse impacts on aquatic life. 

Increasing: 1.  Driftwood Branch Sinnemahoning Creek 2.  Kitchen Creek 3.  Long Run 4.  Sugar Run 5.  Choconut Creek

Decreasing: 1.  Susquehanna River at Kirkwood

Map: Water Temperature Trends by CIM Station.

In addition to the CIM data, macroinvertebrate data were routinely collected at 43 of the 45 sites. Macroinvertebrate taxa (types of aquatic bugs) have different water quality tolerances, and changes in water quality can be reflected in shifts in macroinvertebrate communities.

Changes in stream temperatures could impact macroinvertebrate community structure as some taxa are generally classified as cold or cool water taxa and would not be expected to be found in warmer streams.  There was no significant difference (p=0.915) between macroinvertebrate communities in streams that were getting warmer and those that had no temperature trend.  There were no macroinvertebrate data for the Susquehanna River which has a decreasing temperature trend.

There are 13 stations with decreasing dissolved oxygen trends:

1.  Baker Run 2.  Baldwin Creek 3.  Bowman Creek 4.  Driftwood Branch Sinnemahoning Creek 5.  East Fork Sinnemahoning Creek 6.  Lackawanna River 7.  Little Clearfield Creek 8.  Little Muncy Creek 9.  Long Run 10.  Marsh Creek – Tioga County 11.  Upper Pine Creek 12.  Portage Creek 13.  South Branch Tunkhannock Creek

Dissolved oxygen and water temperature have an inverse relationship: as water temperatures rise, DO levels decrease.  However, only two of the stations with decreasing DO trends also illustrated increasing temperature trends (Driftwood Branch Sinnemahoning Creek and Long Run).

Map: Dissolved Oxygen Trends by CIM Station.

No significant difference (p=0.419) was seen in any of the macroinvertebrate communities or ranges of IBI scores across sites with a decreasing trend or sites with no dissolved oxygen trend.  

Ten stations have decreasing pH trends, while seven stations illustrated increasing pH trends.  Because the optimal range for pH is between 6 and 9, increasing or decreasing trends can be beneficial or detrimental to water quality.

pH affects most chemical and biological processes in water.  Streams with pH values outside of the optimal range may see reduced fish and macroinvertebrate diversity, stunted growth or disease.  The pH of water impacts the availability of pollutants (i.e. metals) which can adversely impact aquatic life.

Map: pH Trends by CIM Station.

Four of the stations with increasing pH trends have average pH values of 7 or greater.  These increases are detrimental to stream water quality and three of these stations (Little Muncy Creek, Portage Creek, and Sugar Run) experienced pH conditions exceeding the water quality standard limit of 9.

East Fork Sinnemahoning Creek, Moose Creek, and Trout Run have increasing pH trends; however, on average, these sites are acidic, so an increase in pH is considered beneficial.  All stations with decreasing pH trends are beneficial to water quality; seven of the 10 stations had pH conditions that exceeded the water quality limit of 9.

Significant differences (p=0.01) were found between macroinvertebrate communities that had no trend, increasing, or decreasing pH.  The biggest differences were between sites with no trends and those with increasing pH, which were nearly 70 percent dissimilar. The largest differences in taxa are simply different types of mayflies with very similar tolerance values in each group.  For example, at sites with no pH trend, three Ephemerella on average were collected compared to one at sites where pH was rising, but at the sites where pH was rising, an average of three Epeorus were found, compared to one at sites with no trend.

Nineteen stations have significant turbidity trends, with 17 indicating an increase in turbidity.

Increasing: 1.  Baker Run 2.  Bobs Creek 3.  Catatonk Creek 4.  Chemung River 5.  Chest Creek 6.  East Fork Sinnemahoning Creek 7. Lackawanna River 8. Long Run 9. Loyalsock Creek 10. Moose Creek 11. Portage Creek 12. Sing Sing Creek 13. Starrucca Creek 14. Susquehanna River at Kirkwood 15. Tioga River 16. Trout Run 17. Tuscarora Creek

Decreasing: 1.  Marsh Creek - Tioga 2.  Pine Creek

Stations with decreasing turbidity trends experienced a mix of land use changes; no definitive relationship exists between an increase in turbidity and land use change (boxplot).  While more stations with increasing turbidity trends experienced an increase in agriculture, an average of about 4 percent, more stations with no turbidity trend also saw increases in agriculture at a rate of almost 6 percent (see table below). 

Map: Turbidity Trends by CIM Station.

A one-way ANOVA was used to determine if stations with increasing, decreasing, or no trend in turbidity had significantly different (α≤0.05) watershed characteristics.  A significant difference in percent alluvium (geologic material) was observed for stations with increasing, decreasing, or no turbidity trend.

A small but significant difference (p=0.001) between macroinvertebrate communities at streams with no turbidity trend, increasing turbidity and decreasing turbidity was observed.  However, no difference was seen between sites where turbidity was increasing and those where it was decreasing.  The only taxa differences were between sites with no trend compared to increasing and decreasing turbidity, which were both about 60 percent dissimilar.  However, once again the taxa differences were largely inconclusive with no obvious shifts in sensitive taxa where turbidity is increasing.

Hunts Run and Grays Run geographical characteristics are illustrated in the table on the bottom right. Most of the watershed's attributes are similar with the exception of unconventional natural gas well related statistics.

Images: Hunts Run on the left, Grays Run on the right.

The Susquehanna Water Quality Index (WQI) is comprised of three categories which represent the major threats to water quality in the basin; metals, nutrients, and development.  Overall WQI scores and the spread were virtually identical with variability showing in the Category scores.

Box plot: Watershed WQI and category scores.

Annual fluctuations in category scores by year were slight with no overall trend as shown on the chart at right. A small portion of Grays Run is impaired for atmospheric deposition impacting the metals category score, as aluminum in the stream from atmospheric deposition can vary with precipitation.

Unconventional natural gas development has the potential to increase certain analytes in surface water such as barium, bromide, strontium and total dissolved solids (TDS).

Images: Aerial photo comparison between Hunts Run, with no natural gas infrastructure, and Grays Run, with numerous natural gas pads.

Ten years of data show little difference between the sites. The charts at right show that in Grays and Hunts Runs, bromide was below the detection limit in 100%  and 86% of the samples, respectively.  Barium, strontium and TDS were always detected but at low levels of no concern.

Aquatic macroinvertebrates are one biotic indicator that can be tracked in a number of ways over time in order to monitor biological integrity and stream health.

Image: Commission scientist collects a macroinvertebrate sample.

The PA IBI provides a summary score (0-100 scale) of the quality of the macroinvertebrate community based on six metrics which reflect abundance, diversity, pollution tolerance, and sensitive taxa. Mean scores for each of the 6 metrics is shown in the table at right.

Both Grays Run and Hunts Run have consistently scored high on the IBI scale with scores typically greater than 80 with minimal variation.

An alternate way to look at macroinvertebrate assemblages to identify differences is to examine community similarity using nMDS plots (at right).   Despite very similar IBI and metric scores, there are significant differences (ANOSIM 0.272, p= 0.0013) in the macroinvertebrate taxa that comprise the assemblage in each stream. Hunts Run tends to support more mayflies while Grays Run has more stoneflies and caddisflies, but because of similar tolerance values and the general importance of all three families (EPT) in stream health, the differences generally offset each other in the metrics.

Natural annual variation is common in biological communities. For each stream, an arrow connects points from the first sample to the most current sample, the closer the point, the more similar the samples.  It is evident that the macroinvertebrate communities at Grays and Hunts Runs are different as their trajectory points do not overlap.

In Grays Run, the current samples are most similar to the samples from 8-10 years ago, providing more evidence for natural variation as opposed to gradual change from what was there a decade ago.  In Hunts Run, there are fewer samples but the trajectory folds in on itself and the samples all cluster fairly closely.

Another biological indicator that can be used to signal changes in an aquatic ecosystem is fish.  Fish communities were sampled multiple times at each site over the last decade, although Grays Run was sampled more frequently. 

Both sites support fairly typical fish communities for cold headwater streams, although Hunts Run has higher diversity while Grays Run is more trout and sculpin dominated.  Grays Run supports 7 species but is heavily dominated by trout and sculpin while Hunts Run supports 12 species, with fewer trout but still sculpin dominated.

Table: Fish survey results.

Because Grays Run was sampled more frequently we can look at ratio of brook trout to brown trout over the years as well as trout biomass over time. Brook trout biomass was consistently 30-40% of the biomass of brown trout across the period of record. 

Image: Brook trout.