Missouri's Castor River forms near Silver Lake in Ste. Genevieve County on the eastern edge of the Saint Francois Mountains, then flows south to Gipsy in Bollinger County where it turns east and flows a short distance before turning southeast, then northeast, on its way to its Mississippi River confluence south of Cape Girardeau. The Whitewater River flows into the Castor south of the Town of Whitewater and northwest of Delta. The upper reaches of the river are a narrow "shut-in" stream formed by rushing water eroding away relatively soft limestone and dolomite until it reached the deeper igneous rock, in this case in the form of pink granite and rhyolite. The river is characterized by dense stands of willows, old growth shortleaf pines and cedars along the banks and the surrounding fields where azaleas bloom in May. While most of the river has a relatively gentle gradient, the area around Amidon Conservation Area and Hahn's Mill Shut-in features a steeper 75 fpm drop with great whitewater rapids rated Class II to IV.
The Castor is not a perpetual flow river, and is only navigable in or near flood stage conditions which occur shortly after significant rain events pound the surrounding drainage basin. The Amidon area is home to over 136 species of plants, 35 species of fish including smallmouth, largemouth, spotted and shadow bass, as well as sunfish. It is also home to spothanded and golden crayfish, two species that are found only in the Ozarks. Local plants include many varieties of wildflowers and grasses including wild hyacinth, prickly pear cacti, little bluestem, pencil flower, pineweed, rushfoil, flowering spurge and sundrops. A wide variety of wildlife is found along the Castor River where hunters go for deer, turkey, squirrels and other small to medium game. The waters are cool, clean and clear with an aqua green coloration on this very remote stream flowing a few miles east of the Saint Francis and Black Rivers of far southeastern Missouri near the Illinois, Kentucky and Tennessee borders. Its upper reaches flow through the Mark Twain National Forest. Excellent water quality and gorgeous scenery are characteristic of the river, especially above Gipsy. While most of the river is technically navigable, a very short area of about 1.5 miles around Hahn's Mills Shut-in is the reach most commonly paddled because of its awesome scenery, big drops and relatively easy access from Fredericktown and SH 72. Ledge drops into pools with occasionally strong hydraulic currents, tight chutes and rocky shoals produce interesting paddling conditions for those with skills and experience to quickly see their lines, then execute the maneuvers necessary to hit them. However, when the river flows at navigable levels it is possible to paddle it all the way to the Mighty Mississippi.
Far southeastern Missouri in Ste. Genevieve, Madison, Wayne, Bollinger and Cape Girardeau Counties. The nearest sizeable town is Cape Girardeau on the Missouri-Illinois border. St. Louis is about 100 miles north of the headwaters. Fredericktown is just west of the first practical access point at Hahn's Mill in the Amidon Conservation Area.
St. Louis 85 miles; Joplin 337 miles; Springfield 265 miles; Kansas City 434 miles; Memphis 256 miles; Little Rock 280 miles; Oklahoma City 624 miles; Dallas 605 miles; Austin 800 miles; San Antonio 880 miles; Houston 714 miles; Albuquerque 1,161 miles; Phoenix 1,605 miles; Denver 1,040 miles; Salt Lake City 1,539 miles (all distances are approximate and depend upon starting point, destination point on the river and route taken.)
Very good to excellent, flowing clean, clear and cool with an aqua green tint. Navigable flows depend upon recent local heavy rainfall that swells the river to or near flood stage conditions. Otherwise, the Castor River has insufficient flow for recreational paddling, though it is usually more than adequate for great fishing.
The optimum time to paddle the Castor River is in spring or fall, during periods of significant local rainfall. The river may be navigable at other times following a major local rain event, as well.
Hazards include dense willow stands lining the narrow banks, ledge drops with strong hydrauic currents, rocky shoals, small waterfall drops (in the Hahn's Mill Shut-in area) and the overall remoteness of the stream. Around and just below Amidon Conservation Area, where most runs begin, rapids are rated Class II to IV, and will require strong boating skills and preferably short boats to navigate the tight turns through narrow chutes. After departing the Amidon area most hazards will be the continued presence of willow trees and potentially willow strainers along the banks or hanging into the narrow stream.
Madison County Road 253 southeast of County Highway J and east of County Highway W east of Fredericktown at 0.0 miles; Low-water bridge on gravel road in Amidon Conservation Area off SH 72 and County Highway W east of Fredericktown at 1.5 miles; SH 72 bridge below Amidon CA at about 6.5 miles; Low-water bridge on gravel road off County Highway F south of SH 72 at about miles; Low-water bridge on County Highway V east of County Highway F at about miles; Bridge on County Highway A near the intersection of County Highways M and DD at the Town of Marquand at about miles; Bridge on County Highway DD south of Marquand at about miles; Low-water bridge on gravel road off County Highway DD a few miles north of the Castor Conservation Area at about miles; Low-water bridge on gravel road between County Highways M and MM just northwest of Castor CA at about miles; Low-water bridge on gravel road between County Highways M and MM just west of Castor CA at about miles; SH 34 bridge just west of the intersection of County Highways MM and Y at about miles; Gravel road crossing north of County Highway E near the Town of castor at about miles; SH 51 bridge just outside Zalma at the Maple Flats AC at about miles. There may be other access points for the Castor River.
There are at least two commercial campgrounds located along the Castor River.
Rentals and shuttles are available from at least two commercial outfitters located along the Castor River.
Though not always runnable, the Castor River offers whitewater excitement and a remote wilderness experience for those fortunate enough to be there when local rains swell the river to navigable levels. Springtime runs are ideal because of the combination of great water, awesome scenery with plants in bloom, mild temperatures and a perpetual lack of crowding. While there is some canoeing, kayaking and tubing on reaches below Hahn's Mill Shut-in, the Shut-ins themselves are usually left to those with sufficient whitewater skills to safely negotiate the tight, technical chute runs, ledge drops and challenges of a section with a steep 75 fpm gradient that, at just 1.5 miles, could be run multiple times in a day. The Castor River is also very near the Saint Francis and Black Rivers, both of which are probably navigable anytime the Castor has adequate flow for paddling. Access is plentiful, though you might need a GPS to find some points - they are located along gravel roads that lead off state or county highways, most of which are running north to south along the general run of the river. The upper reaches start in the Mark Twain National Forest, and several state conservation areas line the banks between Hahn's Mill Shut-in and Maple Flats Conservation Area near Zalma. Beautiful pink granite is found all along the river, along with a spendid array of grasses, wildflowers, indigenous plants, collared lizards, deer, turkey, squirrels, rabbits and many types of birds. The river offers excellent fishing, though some limits on size and seasons do exist for some species - have a valid Missouri fishing license and know the rules before wetting a hook. Local outfitters can provide additional details about the river and current conditions.