Creek Bottom Composition

The characteristics of the bottom can have a major impact on many of the creeks physical and biological attributes. Turbidity (amount of particulate matter suspended in water), pH, temperature, and phosphate concentrations are influenced greatly by the characteristics of the creek bottom.

We use sieves that have decreasing sizes of pores and stack them on top of one another in decreasing order from top to bottom. A shovel full of the creek bottom is placed into the stack of sieves and then shaken. The sieve trays are then separated and the percentage of each size of bottom material is estimated.

The characteristics of the creek bottom will vary depending primarily upon rate of flow. Where flow is fastest, larger gravel and rock will make up the greatest percentage of bottom material. Where rate of flow is near zero, clay and sand will make up the greatest percentage. This can change as the shape of the creek channel changes.

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