WSP04463

• File Number: 8460.500
• Description: Platte River Recovery Plan
• Basin: South Platte
• Date: 6/1/1997
• Author: Colo Div of Wildlife
• Title: Inventory and Status of South Platte River Native Fishes in Colorado
• Water Supply Pro - Doc Type: Publication

Plains topminnow and fathead minnow followed with 5 to 6 percent oftotal collections, and
johnny darter, largemouth bass, common shiner, commO\l carp, and brook stickleback each added
more than I percent. Iowa darter, longnose sucker, broWn trout, yellow perch, and stonecat were
each found in several locations. Over 20 specimens of e~ch of these species were captured
(approx. 0.5-1% of the total). The rest of the species represented in collections (in decreasing
order of abundance) were red shiner, green sunfish, plains killifish, mosquitofish, bluegill, brassy
minnow, white crappie, smallmouth bass, and channel catfish.

Introduced species collectively made up less than 0.5 percent of the total collection. Half
of the introduced species found were largemouth bass, but 108 out of 109 fish found in our
samples were likely young-of-the-year immigrants fromladjacent gravel pits. One fish was about
six inches long, and may have survived in the river for ~ year. However, no evidence was found
that largemouth bass survive in the river to the extent of creating a predation threat.

Propst (1982) reported significant changes in species abundance, presence, nomenclature,
and difficulty in documenting reliability ofinformation !lbout species status at the turn of the
century from the accounts ofJordan (1891), Juday (1995), and Ellis (1914). However, the status
of St. Vrain fishes from the 1950s and 1960s (reports by Hendricks (1950), Beckman (1952) and
Li (1968)) was relatively unchanged when Propst samrlled in the late 1970s after Colorado's Front
,
Range (including the St. Vrain drainage) had become ~\.xbject to human population pressures,
industrialization and intensive water manipulation. '

The most obvious management strategy for the mainstem St. Vrain involves protecting
and enhancing the valuable resource, which is already present. In 1994, the CDOW and the city
of Longmont joined in a project to help create more deep plunge-pool instream habitat, and to
place rock and boulder structure to create overhead cave-like cover in the plunge-pool
approaches and tail ends of the pools. These efforts specifically targeted enhancements of habitat
for common shiner and stonecat. This project also cr~ated off-channel isolated pools which will
articulate with the river at high flows. Future efforts ~hould involve water quality analysis to
determine potential limiting factors between the upstream reach of the river above the confluence
of Left hand, Boulder and Dry creeks, the downstream reach of the St. Vrain River, and the
tributary creeks as well.

;
Fifty-two sites were sampled on St. Vrain drainage tributaries (Table 19). These were all
located in the foothills transition zone or plains dra;n~ge areas. Sampling efficiency was generally
good throughout the drainage. Several targeted site~ in the agricultural area near Frederick and
Firestone were never sampled because the streams,w'ere high and turbid throughout the sampling
season. Agricultural irrigation runoff was frequently encountered, but most sites were sampled on
streams under low, clear water conditions.

The fish populations found in these tributari~s varied significantly over those found in the
mainstem St. Vrain. Fathead minnow, longnose dac,e, creek chub, white sucker, and green sunfish
comprised 86 percent of the total, with uncommon 9r environmentally-sensitive species, which
were abundant in the mainstem, making up only 2 percent (Table 20), Largemouth bass, brown

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