|Sponsor:||Spray Lake Sawmills|
Object & Deliverables
The overall project objectives are to continue to collect data to assist in the development of a regionally specific ecosystem based timber harvest plan, to develop a framework that allows the identification and evaluation of changes in aquatic resources over time, and to make recommendations for future monitoring programs. To meet the overall objectives, biological diversity of benthic macroinvertebrates, presence or absence of sport fish, stream habitat measurements and classification, and temporal patterns in selected physicochemical characteristics of surface water data were collected, analyzed, and where appropriate compared.
The study site for the Etherington Creek Aquatic Ecosystem Baseline Extension Study includes six creeks: Baril, Cataract, Etherington, Lost, McPhail, and Wilkinson. Samples were collected in the fall of 2003 (October 3rd to 5th).
Sample locations were restricted to suitable reaches near the downstream boundary of the Etherington Creek Study Area. For Wilkinson Creek and Etherington Creek, sample locations are far enough upstream to avoid disturbance by campground activity. The rationale for selecting downstream sites reflects a cumulative effect approach. The Etherington Creek Study area is a multi-use area with various stakeholders including recreational users (anglers, hunters, campers, hikers, bikers, equestrian, and off-road vehicle users), cattle grazing, oil and gas exploration, and the lumber industry. Therefore, not only is Spray Lake Sawmills input considered, but also the influences of most inputs are taken into account and resultant effects analyzed.
All streams continue to be dominated by Ephemeroptera, Plecoptera, and Trichoptera (EPT) comprising from 46% to 62% of the total benthic macroinvertebrate community. As expected, there is a significant difference in total benthic macroinvertebrate density between the six streams for fall 2003.
Five of the six streams show no significant difference between fall 1999, spring and fall 2000, fall 2001, fall 2002, and fall 2003 total benthic macroinvertebrate density. McPhail Creek continues to show significant variability in total benthic macroinvertebrate density. By changing the flow regime, the beaver activity in the study area of McPhail Creek may be playing a role in changing the species composition.
The results for the following analyses are the same as those determined in the fall of 2002. Three of the six streams show no significant difference between the fall of 1999, spring and fall 2000, fall 2001, fall 2002, and fall 2003 EPT density. There were however, significant differences recorded for Wilkinson, Cataract and McPhail Creeks. Four of the six streams show no significant difference between fall 1999, spring and fall 2000, fall 2001, fall 2002, and fall 2003 EPT relative abundance. There were however, significant differences recorded for Cataract and McPhail Creeks. Four of the six streams show no significant difference between fall 1999, spring and fall 2000, fall 2001, fall 2002, and fall 2003 Baetis spp. density. There was however, a significant difference recorded for Etherington and McPhail Creeks. Five of the six streams show no significant difference between fall 1999, spring and fall 2000, fall 2001, fall 2002, and fall 2003 Baetis spp. relative abundance. There was however, a significant difference recorded for Etherington Creek.
Even with the low flows experienced in the fall of 2001 and the fall of 2003, these benthic macroinvertebrate data indicate that, for the most part, fall 1999, spring and fall 2000, fall 2001, fall 2002 and fall 2003 sampling events are equivalent and little community composition change occurred between sampling events. Furthermore, given the similarity in measured physicochemical parameters from year to year, these data indicate that Wilkinson Creek, McPhail Creek, Cataract Creek and Etherington Creek show a healthy variability from year to year. The power analysis used to determine the number of replicates per sampling event (n) assures 80% certainly that a 50% difference between means was detected at the 5% significance level. As more years of data are collected, normal aquatic ecosystem variability will continue to be detected.
Stelfox and Ladd (1982) collected stream characteristic data for the creeks in this study. Their measured wetted width data is consistent with the measurements collected by Townsend (2000, 2001, 2002, and 2003) and this study. There is no significant difference in stream habitat data collected by Townsend from 1999 through the fall of 2003.
Mean substrate size indices for all streams range from 3.6 to 4.5 with the standard deviation ranging from 0.88 to 1.45. These Bain, et. al., (1985) indices continue to indicate an intermediate coarse and heterogeneous substrate in all six streams. For example, all substrate data collected for all Etherington Creek Aquatic Ecosystem Studies show mean substrate size indices ranging from 3.2 to 4.7 with the standard deviation ranging from 0.88 to 1.45. Water temperatures ranged from approximately 1 to 8 °C.
In the six streams, three trout species were identified (cutthroat – Oncorhynchus clarki; and brook trout – Salvelinus fontinalis; and bull trout – Salvelinus confluentus) ranging in size from 10 to 38 cm. The largest number of sport fish were observed in Wilkinson Creek with 35.
Potential spawning sites for Wilkinson are consistent with the locations originally identified in the fall of 2000 (Townsend, 2001). Wilkinson Creek has potential spawning sites at approximately 150 m and 740 m from the downstream start of the aquatic survey. The potential spawning locations identified in McPhail Creek have changed again. The beaver dam constructed in 2001 has since been removed. The previously flooded spawning sections (approximately 872 m and 990 m) still contain to much sediment to be considered potential spawning locations. As the years pass and the sediment is washed out, the section may return to their pre-flood spawning potential. Therefore, McPhail Creek still has three potential spawning locations at approximately 400, 415, and 445 m from the downstream limit of the aquatic survey. Etherington Creek has two at approximately 865 m and 950 m from the downstream start point of the aquatic survey.
There is an apparent decrease in species richness in Etherington and Baril Creeks since 1982. Stelford and Ladd (1982) caught brook trout, rainbow trout, bull trout, and cutthroat trout in Etherington Creek, however; only cutthroat trout were identified by Paul (1999) and by visual observations in the fall of 1999, 2000, 2001, 2002 and 2003. Downstream of the impassable barrier on Baril Creek, Stelfox and Ladd (1982) again caught brook trout, rainbow trout, bull trout, and cutthroat trout, but Paul (1999) identified only cutthroat trout.
All studied aquatic ecosystems continue to be highly oxygenated and slightly alkaline. Total suspended solids (TSS) were below detectable limits for the 6 six streams. Since the fall of 1999, Wilkinson Creek TSS levels were consistently higher than that found in the other streams. This may be due in part to unstable banks in the upper reaches of Wilkinson Creek. It was interesting to note however, that Wilkinson Creek TSS levels were below detectable limits this year and there was a relatively large filamentous algae bloom as well.
Discharge rates were relatively low for all six streams. These discharge rates were most similar to those recorded in fall of 2001.
Total nitrogen, total phosphorus and dissolved organic carbons levels remain negligible. In 1980, Stelfox and Ladd (1982) collected stream characteristics data for the same six streams. Nitrate and nitrite, pH, and discharge levels are similar in all four studies indicating little change over the past 20 years in the physicochemical parameters measured.
For future benthic macroinvertebrate sampling, the number of replicate samples to be collected so there is an 80% certainty of detecting a 50% difference between means at a 5% significance level during the next sampling event n=5 for all streams, except Cataract Creek where n=6. Sport fish observations should continue in future studies. Habitat analysis should also continue in future studies however, Stream Classification (Rosgen, 1994 and 1996) should not be conducted until up to datE aerial photographs are available.
Given the low levels of some of the physicochemical parameters, future studies should continue to measure total phosphorus and total nitrogen. These measures should continue until significant changes are identified in the total concentrations then fractions should be isolated. Maxxam laboratories or another comparable commercial laboratory should be used, because their measurement are more precise given the low physiochemical levels found in these streams.