WSP04165

• File Number: 8240.200.10.B
• Description: UCRBRIP - Riverine Fish Flow Investigations
• Basin: Colorado Mainstem
• Date: 6/1/2003
• Author: CDOW
• Title: Riverine Fish Flow Investigations 2003
• Water Supply Pro - Doc Type: Publication

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sampling scheme was used as in 2000 except a seventh pass was performed in the mid-
river zone. The additional mid- river pass was found necessary to improve the recapture
probabilities for large fish mid-channel. The dates and the mean daily flow (Palisade
gage) for that day for the period of sampling is given in Table 3.

The Dolores River was electro-fished in July 2000 and 200 I. In both years on the
first pass block nets were placed at the downstream end of each run (upstream ofriffies)
Also, each run was repetitively electro-fished three to five times. Fish from each pass
were held in nets, then marked and released into the same run of capture. This process
was continued over the entire reach. Block nets were not used on recapture passes.
Dates of electro-fishing and flows from the Slick Rock gage is given in Table 3.

CHANNEL TOPOGRAPID'

Global Positioning Systems and Sonar

In 1999 and 2000, bathymetric surveys of the channel were taken of the six study
sites using Global Positioning Systems (GPS) and sonar technology. The channel
surveying technique previously described in Anderson and Stewart (2000) was performed
from a moving boat. A large amount of bathymetry data was gathered in a short amount
of time. The GPS system was a Javad Oddessy LlfL2 RTK GPS with Glonass and Multi-
path reduction options turned on. The system had a published vertical accuracy of 15mm
+/- 1.5 mm. The sonar unit was an ODOM Hyrographic Systems, Hydrotrac - Single
Frequency, Portable Survey Sounder The sonar unit used a 200kHZ frequency with a
published accuracy of I cm +/- I % of depth and an output resolution of I cm The sonar
unit pinged and logged ten depth readings per second. The RTK GPS logged one
position per second. The RTK GPS system output a NMEA GGA string at a rate of 1Hz
while the sonar output text strings indicated depth at a rate of 10Hz. Data from these
instruments were sent to a laptop computer and recorded using the COMLOG software
from ODOM Hydrographic. Because the RTK GPS and Sonar data were received at
different rates, all data entries collected by the COMLOG software were time-tagged to
the millisecond using the computer's clock. The depth readings immediately before and
after the RTK GPS reading were interpolated by the computer clock time (nearest
millisecond) to produce the XYZ coordinates used to map bed topography of the river
channel

Bathymetric data were collected from longitudinal runs and cross-sectional
surveys. Special care was taken to ensure that the transducer and GPS antenna were
mounted in such a way as to remain nearly vertical during each run