Bear Creek Effectiveness Monitoring Program

Data was evaluated by station (location), season, month, year, and and compared to the TMDL standards. In addition, the data was analyzed using a number of different methods including linear regression, box plots, and Seasonal Kendall to allow us to compare between stations and also allow us to look at trend information.

1. Linear Regression Analysis

2. Percent Attainment by season

3. Geometric Mean by Season

4. Box Plots

• Sites in the upper portion of the watershed had the best water quality. Specifically, sites E04 and E05 on Ashland Creek, and sites E07-E09 on Bear Creek reported some of the lowest median concentrations of E. coli and total phosphorus. However, compared to other upper watershed tributaries, water quality at site E03 at the mouth of Neil Creek was not as good – the site had the fourth and tenth highest median concentrations of E. coli and total phosphorus, respectively.
• While site E10 below the Medford Irrigation Diversion structure reported the highest concentrations of E. coli, the site had the 7th lowest median total phosphorus concentration. The results suggest factors specific to E. coli are influencing water quality conditions at the site.
• Median E. coli concentrations on Bear Creek between the City of Phoenix and the City of Medford (sites E11-15; E20-21) were higher than at the mouth of Bear Creek near Kirtland Road (site E24).

• There was a large difference in the median E. coli concentrations during the irrigation season at the two sites located on irrigation infrastructure. Site E10 on the Medford Irrigation District conveyance system reported the highest median concentration (687 MPN/100ml) and less than 25% of samples were below the standard. In contrast, site E06 on the Talent Irrigation District conveyance system reported a median bacteria concentration of 243 MPN/100ml and more than 75% of samples were below the standard.

Phosphorus levels exceed the standard in over half the stations in the watershed. The data suggests that there are multiple sources of phosphorus in the watershed. In the 2000 Bear Creek Watershed Assessment, it was estimated that the Ashland Wastewater Treatment Plant (WWTP) was responsible for 85% of the phosphorus loading to Bear Creek. Treatment plan upgrades addressed the concerns from the WWTP. Additional monitoring is need to identify sources of the phosphorus.

• 7-day average daily maximum water (7DADM) temperature was calculated using continuous water temperature data taken from July – September in 2016-2018 at two sites on Bear Creek – downstream of Lynn Newbry park in Talent, and at Blue Heron Park in Phoenix. The data were analyzed against the water quality standard of 18 °C. At both sites, the 7DADM standard was exceeded from July through the middle of September. The lowest frequency of exceedances was 84% (77 out of 92 days), which occurred in 2018, and the maximum frequency was 90% (83 out of 92 days), which occurred in 2016. 

• For E. coli concentrations, the results of the Seasonal Kendall test indicated only one site in the watershed had a statistically significant trend. Average E. coli concentrations on Walker Creek (site E01) increased by 13 MPN/100ml per year during the period of record (p-value = 0.03), indicating declining water quality conditions. Site E10, located on the conveyance infrastructure below the Medford Irrigation diversion dam, had a marginally significant trend (p-value = 0.08) of improving water quality. Average annual E. coli concentrations at E10 decreased by 35 MPN/100ml over the period of record.
• For total phosphorus, the Seasonal Kendall test identified three sites on tributaries in the upper watershed had statistically significant trends – all of which indicated declining water quality. Average annual total phosphorus concentrations increased 0.01 mg/l at site E01 on Walker Creek (p-value <0.01) and site E03 on Neil Creek (p-value <0.01), and by 0.003 mg/l on the upstream sampling location at site E04 on Ashland Creek near Granite Street (p-value = 0.03).
• Walker Creek (site E01) had the third lowest median concentrations of E. coli and total phosphorus over the period of record. However, the Seasonal Kendall test found statistically significant increasing concentration trends for both parameters, indicating deteriorating water quality at the site. The percent of samples that attain the water quality standard for E. coli at this site decreased over the period of record during the irrigation season but have remained flat during the winter months – suggesting activities or conditions between May 1 and October 15 may be a contributing cause of exceedances.
• For both E. coli and total phosphorus, the Seasonal Kendall test showed the majority of sites did not have a statistically significant trend over the period of analysis.

1. Continue to monitor streams and storm drains in the watershed.
2. Convene a monitoring Technical Team to make recommendations for changes to the monitoring program (if any). The group should meet periodically to discuss monitoring concerns.
3. Additional investigation is needed to isolate potential sources of pollutants. Investigation would involve additional sampling, GIS analysis, field surveys, local knowledge, and/or other factors.
4. Selected monitoring locations can be used to identify the impacts of BMPs and other implementation plan actions.
5. With the recent impacts of the Almeda and Table Rock fires, current and future data collection efforts should consider the short and long term effects of the fire.

In addition to the effectiveness analysis, the data is being used to inform the TMDL program. Specifically, for locating and prioritizing implementation actions including riparian restoration, in creating a watershed report card for the basin, and in our education and outreach programs.

Areas in need of riparian protection or restoration or ones that have been successful are being identified. Local programs emphasize the use of native species, control of invasive species, and multi-objective goals including improving water quality, providing shade to lower temperatures, providing habitat for local species including pollinators, recreation, and aesthetics. Local programs follow procedures outlined in the  Bear Creek and Rogue Basin Riparian Plan  or similar strategy.

TMDL Goals:

1. To increase the number of stream miles restored annually until all streams needing restoration are completed.
2. Plant 1,000 trees and shrubs in the basin annually.
3. Increase shade to maximize stream shading to lower stream temperatures.

Continued education and outreach is needed to continue to improve water quality, especially on private lands and in rural and upland areas. Data can help inform where actions are needed, where we are having successes, and direct actions to focus on specific needs/parameters of interest.

We are working with partners to develop a Watershed Report Card for the Rogue Basin. The data collected for the TMDL program will be used for the Bear Creek portion. For the initial Report Cards, Bear Creek and Little Butte Creek are the pilot areas. The report card provides a visual tool that can be used with the public, decision makers, and others.

Data prepared for submittal to DEQ.

Additional analysis was completed for all of the stations by RVCOG. Results are being used to inform TMDL future TMDL implementation actions including the development of the 5-Year TMDL that were due to DEQ in the Spring of 2020.

Based on the study results, we are currently looking at the distribution of sampling locations across the basin to see if changes are needed. A technical team is being developed review the sample sites and recommend any changes.