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The report from the White River Algae Working Group in your March 15 issue seems to imply that we don’t know enough about conditions in the White River to begin remediation. It is true that we have not yet identified all the particular sources of excess nutrients causing the algae bloom, and careful investigation by USGS is warranted. But we already know plenty, and it is past time to start fixing the problem.
There are many signs that the river is sick. Several independent observers have documented algae sources at the top of the algae bloom on the river upstream from Meeker, but the algae bloom is only the most obvious sign of trouble. Populations of aquatic insects, e.g. mayflies, caddisflies, stoneflies, etc., are diminished; there is anecdotal evidence that fish populations are changing; and water chemistry is changing, especially dissolved oxygen concentrations which drop to dangerous levels during a bloom.
Many factors, not just nutrient load, contribute to the problem. Here’s what is known from the research literature and many studies already accomplished on the White River:
1. Spring runoff occurs earlier, and peak flow is trending downward. Early runoff gives algae a longer growing season. Lower flows decrease the scouring that normally removes algae.
2. Aerial spraying with permethrin (and, previously, malathion), as is routine along the river above Meeker, kills aquatic insects.
3. Ponds along the river system heat water and grow algae.
4. Pasture runoff and fertilizer application contribute to the nutrient load.
5. Barriers in the river slow discharge (stream flow), drop sediment, reduce nitrogen removal, provide conditions for algae growth and reduce the overall productivity of the river.
6. Feeding fish adds nutrients directly into the river system.
We can’t control snowpack and runoff (except by reducing CO2 emissions), but we can start to solve the other problems.
1. Stop spraying insecticides. Control mosquitoes, if necessary, with Bti pellets and other measures known safe for aquatic insects (and bees and other harmless insects). (To its considerable credit, Elk Creek Ranch has already decided to stop aerial spraying with permethrin or malathion. We hope others follow their lead.)
2. Remove ponds or, at minimum, drain ponds through wetlands, not directly into the river.
3. Reduce fertilizer application to a minimum. Restore river bank vegetation to remove nutrients from pasture runoff.
4. Remove barriers from the river, and restore the normal channel.
5. Stop fish feeding.
People along the river and especially those who make their living from the river have an obvious interest to restore its health. If everyone does their part, the river can recover. It’s time to start. Now.
Bob Dorsett, MD