Average annual precipitation ranges between 34 and 36 inches (MDNR 1986).
USGS Gaging Stations
There are three active gaging stations in the basin (USGS 1995; Table Hy01). Water quality is monitored at the South Fabius River station.
Permanence of Flow and Average Annual Discharge
Average annual discharge at the three stations ranges between 278 and 413 cfs (Table Hy01). All streams are subject to periods of no discharge. Nevertheless, five basin streams denoted by solid blue lines along their entire length on USGS maps are considered to be permanantly flowing streams (Fabius, North Fabius, Middle Fabius, South Fabius, N. Fork of North Fabius). Most other fourth and fifth-order streams have only short reaches considered intermittent. Many third-order streams are intermittent their entire length.
Base Flow and Low-Flow Frequencies
Base flows throughout the basin are not sustained by groundwater inflow during dry weather due to the low conductivity of the underlying clays and rock. Seven-day periods of no flow occur every 5 to 10 years (Skelton 1976; Table Hy02). Also, stream discharge can fall below 1.5 cfs for 30 days or longer every five years.
Flow duration statistics reflect the stream discharge that is exceeded for a specified proportion of time. Median discharge (flow exceeded 50% of the time) for the North, Middle, and South Fabius rivers is 41, 47, and 62 cfs, respectively. The ratio of the flow that is exceeded 90% of the time to the flow exceeded 10% of the time (90:10 ratio) is indicative of the flashiness or variability of stream flow. The 90:10 ratios calculated for the Fabius River basin indicate that stream flows are highly variable (Table Hy01). Small precipitation events cause rapid increases in stream flow; most water runs off quickly due to the low permeability of underlying strata.
Alexander and Wilson (1995) determined through multiple regression techniques that drainage area and main-channel slope can be used to estimate flood frequency flows for unregulated streams in Missouri (Table Hy03). The generalized least squares regression equations are as follows:
Qt=estimated discharge in cubic feet per second per time interval (t=years)
A=drainage area in square miles
S=main channel slope in feet per mile
Discharges in excess of 5,000 cfs occur every two years in the major streams of the basin.
Dam and Hydropower Influences
There are no major dam or hydropower influences at this time, except that the regulation of Pool 22 of the Upper Mississippi River by the Corps of Engineers can affect water level and flow in the lower two miles of the Fabius River.
Major Water Users
Seven public water supply facilities in the basin withdraw surface water from 13 small reservoirs (Vandike 1995). Two water supply lakes (LaBelle City Lake and Lewistown Lake) have water quality problems related to the herbicide Atrazine (MDNR 1994). Little water is used for irrigation in the basin (MDNR 1986a). Fewer than 1,000 acres are irrigated in Marion County and fewer than 50 acres are irrigated in each of the remaining counties. There are no major industrial water users in the basin.