Source monitoring and evaluation of sediment inputs for Peoria Lake.

This report summarizes the results of a two-year study on the
determination of the input of sediment to Peoria Lake from its
local tributaries.  Ten local tributaries were monitored to
determine the flow of sediment and water.  Long- term average
deposition of coarse material at the mouths of these tributaries
was estimated as bed load based on the progression of the deltas
at the base of the tributaries.  Sediment inflow to Peoria Lake
from the Illinois River was determined based on the estimated
sediment load at the Henry gaging station.  Water year 1989 (WY89)
was essentially a dry year  and WY90 was average.  The present
analyses have shown that about 1.2 million tons of sediment flowed
into Peoria Lake in WY89 and about 2.7 million tons of sediment
flowed into the lake in 1990.  Because of a lack of a
sedimentation survey and nonavailability of sediment outflow data
from the lake, no sediment budget for the lake was determined. 
However, this analysis indicated that in WY89 the sedimentation
rate in Peoria Lake was probably less than that determined on a
long-term basis in a previous Water Survey study, while
sedimentation in WY90 was probably close to or a little less than
that postulated in the earlier study.  Both in-lake and tributary
sediment input controls should be initiated.  They should include
selective dredging and construction of wetlands, marshy areas, and
bank and grade control structures.  Implementation of any sediment
control measure must be preceded by a systematic and systemwide
evaluation of each tributary to determine the most effective
combination of sediment control measures for maximum reduction of
sediment deposition in the lake.