SHERIDAN — With chest waders, two small bottles and a big, green bucket, it is possible to monitor the health of a river.
This month, the Tongue River is receiving its triennial checkup by Sheridan County Conservation District staff who were out Wednesday gathering their third of five samples needed in the month of May.
Carrie Rogaczewski, district manager, and Maria Burke, natural resource specialist, will conduct two more tests by May 29 to conclude early season sampling. They will conduct a late season round of five samples in 30 days in August.
The conservation district monitors for items determined by the state to be issues of concern including bacteria, turbidity (water clarity), water temperature, pH levels, dissolved oxygen conductivity and stream flow.
“We alternate between the Tongue River watershed, the Goose Creek watershed and the Prairie Dog Creek watershed each year because those are the watersheds that we currently have active efforts in, not because other watersheds in the county aren’t important,” Rogaczewski said.
Historically, the conservation district has monitored at 10 sites along the Tongue River. This year, the district added four more sites, starting near the Montana border and working upstream into the Tongue River Canyon. Each sampling day included a total of 16 sites — nine along the Tongue River and seven on tributary creeks that flow into the Tongue River, Rogaczewski said.
Each sample site takes approximately 10 minutes to complete. Burke — the sampler on Wednesday — waded into the river, faced upstream and filled a bucket with water. She handed the bucket to Rogaczewski — the tester — who used instruments to check pH levels and dissolved oxygen conductivity. Burke then filled two bottles with water.
These will be taken to Inter-Mountain Labs in Sheridan to monitor turbidity and bacteria — particularly E. coli — at each of the 16 test sites.
Once results are obtained, the conservation district will update its data for the Tongue River. Using the five bacteria samples (10 by the end of the summer), staff will calculate a geometric mean, which is what the state standard is based on.
“We’ll compare the data from year to year to previous years and previous sites to see what we can understand about the watershed,” Rogaczewski said. “When do we have our biggest times of concern? Is it spring runoff? Is it late season? Is it years when we have high flows? Is it years when we have drought conditions? We relate those questions and answers to improvement projects that are done on the watershed, or to information and education efforts. We just see how things change over the long term.”
Rogaczewski said the conservation district uses the information to update its watershed plans and to determine if there are areas in the river that are regularly of concern. The district does not use the information to pinpoint certain landowners or activities that may be polluting the water. All water improvement programs conducted through the conservation district are voluntary.
E. coli, temperature and water turbidity were the parameters the state determined needed to be monitored after initial assessments were done on each of the three watersheds from 1996-1999.
In September, the conservation district will conduct macroinvertebrate sampling, Burke said. Macroinvertebrate sampling monitors what insects are present in the water at each site. Since insects can live up to three years, it gives a long-term look at water quality.
Different bugs can handle different water conditions, Burke said. If a sample includes bugs that handle warmer water but not bugs that prefer cooler water that may be a sign that the river is too hot.
Likewise, some bugs tolerate pollution better than other bugs. If tolerant bugs are present in the sample but non-tolerant bugs aren’t, it may be a sign of pollution.
Combining short-term “snapshot” monitoring that measures water conditions on a certain day at a certain time with long-term macroinvertebrate samples enables the conservation district to keep close tabs on water health in Sheridan County.