A freestone stream’s water source is either snowmelt or rainfall, so they rely upon precipitation for their flow volume. Freestones generally have steep gradients characterized by areas of rapid and fast currents. They are usually sited in canyon areas.
A freestone stream’s volume crests in early summer while its flow diminishes in the fall and winter. The stark contrast between late springtime and winter flows can be surprising. A once productive summer side-channel may be bone dry in the winter. Springtime flows may be high and muddy yet run low and clear the rest of the season. High flows commonly scour stream channels. Rooted aquatic plants have difficulty surviving the seasonal heavy flows. Stream channels can change from one year to the next. Some scouring may be beneficial if it washes away excess silt accumulated in the rocky, gravelly, riffled sections. Freestones are distinguished by few rooted aquatic plants and by an abundance of gravel and rocks.
Aquatic insects require plants to exist. Riffles support sheltered areas for limited plant growth. Aquatic insects live and feed in the riffled areas where the enhanced surface areas between the rocks support plant habitat. Hence, the riffles provide the freestone stream with its abundance of
aquatic insects for the fish to forage.
A freestone stream’s pH is usually slightly acidic. In times of excess acid, plants, insects, and fish may perish. The snow pack at a stream’s source can accumulate acidic precipitation. This is concentrated into the bottom layer of snow. As this bottom layer melts, the sudden release of acid can be devastating to its downstream environment.
A freestone stream is more readily influenced by the ambient air temperature, resulting in wide temperature fluctuations. Winter cold can cause a stream to run close to freezing while summer heat can cause it to exceed 70°F. This wide variation shortens a fish’s growing season which occurs when the water temperature is between 55-65 degrees. The lowered winter and late summer diminished water volume is more easily influenced by ambient temperature changes. Conditions of bottom ice along with an ice lid surface can induce winter kill of both insects and fish. Likewise, summer die-offs occur due to excessively warm temperatures which forfeit water’s ability to hold sufficient oxygen.
The productive freestone streams are restricted to ideal altitudes and latitudes where seasonal temperatures are favorable for aquatic life.
As a general rule, the freestone stream’s growing season is much shorter than a spring creek’s, because freestones are more prone to wide temperature fluctuations.
In summary, freestones are subject to times of plenty and to times of drought. They are not as rich in food resources as spring creeks. Their grace is that freestones are wider, longer, and more numerous than spring creeks. Nonetheless, freestones are less crowded than spring creeks. Since freestones have fewer fish than a spring creek, an angler must cover more water in search of fish.