Chemical determinations were made on water-samples from my Station 4-S on the Big Blue River, and Station 50-S on the Little Blue ([Table 1]). These samples were taken from the surface in strong current. Determinations were made by methods described in Standard Methods for the Examination of Water and Sewage, 10th edition, 1955.

Table 1.—Chemical Determinations in Milligrams Per Liter at Five Stations in the Big Blue River Basin, Kansas, 1958.

Station
and
Date		Phenolphthalein alkalinityMethyl-orange alkalinityChloridesSulphatesNitratesNitritesAmmoniaPhosphate
4-S
August 9........		0.015416283.5.083.250.225
50-S
August 9........		0.012524202.5.669.427.240
35-M
August 9........		0.0366151089.4.220.750.080
11-G
July 8........		0.027215604.5.060.625.140
18-G
July 22........		0.018310601.6.938.293.240

The banks of both the Big Blue and Little Blue rivers support narrow riparian forests comprised primarily of elm, Ulmus americanus, cottonwood, Populus deltoides, sycamore, Platanus occidentalis, and willow, Salix spp. Maple, Acer sp., oak, Quercus spp., and ash, Fraxinus sp. occur where the rivers flow near steep, rocky hillsides. Many of the hills are virgin bluestem prairies (Andropogon spp.), but the floodplains are heavily cultivated.

Mud-bottomed Streams.—Streams of this kind are present in the watershed of the Black Vermillion River that enters Big Blue River from the east. The area east of the Big Blue River and north of the Black Vermillion River is till plains, where relief seldom exceeds 100 feet (Walters, 1954:12). Streams in this portion of the basin, and streams entering the Little Blue River from the west (Mill Creek and Horseshoe Creek systems), tend to have V-shaped channels, fewer riffles than the Little Blue and Big Blue rivers and in the gravelly streams (to be described later), and have bottoms of mud or clay, with few rocks ([Plate 12, Fig. 1]). However, in the extreme headwaters of most western tributaries of the Little Blue River (in Washington and Republic counties) sandy bottoms predominate. The Black Vermillion River flows on a broad floodplain and is a mud-bottomed, sluggish stream, with an average gradient of approximately one foot per mile. Fringe-forests of elm, cottonwood, sycamore, and willow persist along most of these stream-courses.

Notwithstanding the mud bottoms, the water in this kind of stream in the Big Blue Basin remains clearer than that of the Big Blue and Little Blue rivers. Heavy algal blooms were noted in the Black Vermillion River and Mill Creek, Washington County, in 1957 and 1958. Temperatures at Stations 45-M and 46-M on Mill Creek, Washington County, averaged 85.5° F. on July 31, 1957. Chemical characteristics of a water-sample from Station 35-M, Black Vermillion River, are in [Table 1].

Gravel-bottomed Streams.—Most streams of this kind are tributary to the Big Blue River; however, streams entering Black Vermillion River from the south are also of this type ([Plate 12, Fig. 2]). The streams are "characteristically a series of large pools (to 100 feet in length and more than two feet in depth) connected by short riffles and smaller pools" (Minckley and Cross, in press). The average gradients are high: Carnahan Creek, 33 feet per mile; Mill Creek, Riley County, 21 feet; Clear Creek, 16 feet per mile. Stream-flow is usually less than five cubic feet per second. In summer, these streams may become intermittent, but springs and subsurface percolation maintain pool-levels (Minckley and Cross, loc. cit.).

The average temperatures of these small streams (79.5° to 81.0° F. in July and August, 1957) were lower than temperatures in stream-types previously described. Turbidities were usually less than 25 p.p.m. The chemical properties of water-samples from two of these streams (Stations 11-G and 18-G) are listed in [Table 1].

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