Shagwa - on June 27th 2015, we experienced a near 100% fish kill at Shagwa. We closed Shagwa to any further fishing and conducted several water tests in July and August of 2015. The early tests showed trace amounts of E.coli, which means sewage was entering the lake, and while not at the level to be a human health hazard it was sufficient to impact the fishery. Fortunately, water quality tests of the source water, and at Hiawatha and Papoose showed no water quality issues. We consulted with Larimer County Health Department and have their support as we work to find the source(s) of contamination.
Shagwa investigation work during 2016
- We managed Shagwa as we normally do, by that we mean, filled it during the spring runoff and controlled the algae. However, we did not stock any fish as our primary insterest was to determine the source(s) of contamination and determine a plan to improve the water quality.
- Conducted water quality tests at 5 locations every two weeks during the summer through our consultant, Aquatics Associates, Inc. Tests were run on many parameters, but of particular concern is that they showed E.coli was present throughout the summer. The level of E. Coli was always well below the State and EPA standard of 126 cfu/100ml, however the level increases from 0-9 in May up to 40 during mid-summer, and then returned to 0-4 by the end of August. This indicated the levels increased with cabin usage and that some sewage is entering the lake. While this is not at the level to be a human health hazard, it is sufficient to impact the fishery.
- In September, we hired Farnsworth Group to conduct a hydrology study of the surrounding area. The objective is to understand more about how the water and effluent are moving underground. And make recommendations for next steps (be it more focused study work, mitigation steps, etc.).
- As part of the hydrology study we're working with the surrounding property owners to understand more about their water and sewage solution, their water quality, what testing they've done, etc.
Shagwa work in 2017
- We continued working with surrounding neighbors on the status of their wells and sewage systems.
- In April, we drilled eight core sample holes to better understand the rock composition at the edge of the lake. Four of these were set up for us to take water quality samples, which we did during July and August.
- We took sludge samples at several points across the lake bottom to understand more about the depth and composition of the biomass.
- We drained the lake and trenched the west side so that we could monitor the quality of the ground water that seeps / leaches into the lake.
- While the water samples showed a couple areas of poorer water quality, they weren't definitive enough to identify the source of contamination. No doubt the sludge has been a contributing factor, and we think the elevated water table has helped leach in sewage effluent since late 2013.
- From late October through early December we dredged Shagwa, deepening both the pool in front of the dam and creating a pool and channel in the south end. We also took the top layer from the edges of the south end. In total, we moved 41K cubic yards of material. Reshaping the south end reduces the issue of the shallow water trapping fish in a lower oxygen situation.
Shagwa work in 2018
- Fill the lake, which we did by May!
- We installed a new aeration system. It has six bubblers each on its own air pump, distributed over a greater area of the lake.
- We continued taking water samples, preliminary results are very encouraging.
- After the lake settled and started growing plants, we stocked forage species of crayfish and fathead minnows. We also stocked a few grass carp in the fall.
In 2019 we'll stock the lake and open it for fishing!