Mill Creek (MC-01, MC-02, MC-03, and MC-04)

1) No fish data for 2021. Cumulative and 3-year running averages are through 2020.

Site MC-01: MC-01 had a BIBI score of 2.71(Poor) in 2023, a slight improvement from the previous year.  The site has seen periods of oscillation between “Fair” and “Poor” ratings since 2011. The three-year running average BIBI score is 2.52 (Poor) and the cumulative average is 2.59 (Poor). In 2023, like previous years, true flies were the dominant organism in the sample. 

MC-01 Summary of Insects Collected by Sample Year:

Site MC-02: This site is located upstream of MC-01 and downstream of the confluence of the two reaches that contain MC-03 and MC-04. This site has an intact riparian buffer of approximately 60 meters on both sides of the stream.  In 2023, this site received a BIBI score of 1.86 (Very Poor), the site’s lowest score since 2018.  Like MC-01, and as in prior years, the 2023 sample was dominated by true flies and, to a lesser extent, segmented worms. The cumulative average and three-year running average BIBI condition scores are 2.41 (Poor) and 2.43 (Poor), respectively.

MC-02 Summary of Insects Collected by Sample Year:

Site MC-03: MC-03 is located on the western branch of Mill Creek after the split upstream of MC-02.  It is similar in character to the other Mill Creek sites in that it is well-buffered by a forested riparian area, particularly on the east side of the stream.  

The 2023 BIBI score was 2.71 (Poor).  True flies and worms were the dominant organisms in the 2023 sample, which is consistent with previous years. Caddisflies have been present at the site in all years in which sampling has occurred.  The cumulative and three-year running averages for this site are 2.43 (Poor) and 2.14 (Poor), respectively.

MC-03 Summary of Insects Collected by Sample Year:

Site MC-04: MC-04 is located on the eastern branch of Mill Creek after the split upstream of MC-02.  Like the other Mill Creek sites, MC-04 is well-buffered by a forested riparian area, particularly on the western side of the stream.  The 2023 BIBI score for MC-04 was 2.14 (Poor). The site has received a rating of “Poor” or “Very Poor” for all years of monitoring except for 2018 when it received a rating of “Fair”. The 2023 sample was dominated by true flies and worms.  Caddisflies were present in the sample for the first time since 2021.

MC-04 Summary of Insects Collected by Sample Year:
 

Site MC-01: The site received a FIBI score 3.33 (Fair) in 2022. Nine species were observed in 2022, with the American eel (Anguilla rostrata) and brown bullhead (Ameiurus nebulosus) being the most abundant species.  Fifteen different species have been observed here since 2015, making it the most diverse site in the long-term targeted monitoring program, despite levels of impervious surface (~26%) that often result in depressed fish populations. Also of note, the number of individual fish per sample has more than doubled between 2022 and 2016.

MC-01 Summary of Fish Collected by Sample Year:

Site MC-02: In 2022, like all previous sampling years, the FIBI score was 1.67 (Very Poor). Twenty individual fish, from only two species, American eel and eastern mudminnow (Umbra pygmaea), were collected during the 2022 sampling.

MC-02 Summary of Fish Collected by Sample Year:

Site MC-03: The site received a FIBI score of 2.00 (Poor) in 2022.  The FIBI at MC-03 has been in the “Poor” or  “Very Poor” categories every sampling year.  American eel has been the only species observed at this site since 2018. Six specimens were collected in 2022, a 100% increase over the 2020 sample.

MC-03 Summary of Fish Collected by Sample Year:

Site MC-04: The site received a FIBI score of 1.67 (Very Poor) in 2022, the same score observed in 2018 and 2020. Seven specimens from two species were identified in 2022: American eel and eastern mudminnow.

MC-04 Summary of Fish Collected by Sample Year:

Site MC-01: In 2023, post-restoration habitat conditions resulted in an RBP score of 145 (Supporting).  The site had been rated as “Partially Supporting” or “Supporting” in all years prior to restoration, and scored 156 (Comparable to Reference Conditions) in 2022, immediately following restoration.  The subsequent 3-year running average habitat score is now 142 (Supporting).

Site MC-02: The 2023 RBP score for MC-02 was 109 (Partially Supporting).  The site has consistently been within the high end of scores in the “Non-Supporting” category and low end of scores in the “Partially Supporting” category since 2011.  Despite having a substantial intact forest buffer, low bank stability and sparse bank vegetation continue to depress RBP scores.

Site MC-03: In 2023, the site received an RBP score of 119 (partially Supporting).  Habitat quality is quite variable at this site, fluctuating between “Non Supporting,” "Partially Supporting,” and “Supporting” since 2010.  The cumulative average RBP score is 117 (Partially Supporting) and the three-year running average is 120 (Partially Supporting).

Site MC-04: An RBP score of 122 (Partially Supporting) was obtained at the site in 2023. The habitat has been rated as “Partially Supporting” in 12 of the 14 years of monitoring at the site.   

Site MC-01:  An examination of the cross-section measurements indicates that this stream reach experienced instability prior to restoration (years 2010-2021). Severe incision of the stream bed occurred over that time frame, as the elevation of the channel bottom dropped by nearly three feet between 2010 and 2021. The stream restoration completed in 2022 required the reconstruction of the upper 100 meters of this stream on the opposite side of the river valley.  The 2023 measurements indicated little change in the restored reach since 2022. Future measurements will determine the post-restoration stability of this site.

MC-01 Cross-Section Comparison:

Site MC-02: Little change has occurred in the channel form at MC-02 since measurements began in 2010 aside from an undercut that began forming on the left bank in 2016.  Over the past few years, the right side of the stream channel has experienced fluctuating periods of sediment deposition and scouring.

MC-02 Cross-Section Comparison:

Site MC-03: The channel form at this site has remained relatively stable since 2010, although a slight retreat of the left bank and downcutting on the left margin of the stream bed has been observed over the years. 

MC-03 Cross-Section Comparison:

Site MC-04: The cross-section at this site has shown little change over the 13 years of geomorphic data collection. Incision and deposition have oscillated over the years here, with typical changes from year to year around 0.2 feet or less.  A slight undercut began to form on the right bank in 2021 and, in 2022, a portion of the right bank appears to have slumped off. On the left bank, an undercut continued to worsen in 2023. Future assessments at this site will determine if the site is becoming unstable.

MC-04 Cross-Section Comparison:

SD = Standard Deviation