Smith plantation to New Carthage, connecting with the main levee. There are three breaks in the Vidal Bayou levee, each from 300 to 500 feet wide. The bayou from Richmond to New Carthage offers but little difficulty in obtaining the necessary water-way. At New Carthage, where there is a break in the main levee, there is for several hundred yards but a depth of 2 1/2 or 3 feet. This can be avoided by following Harper's Bayou, branching to the southeast from Vidal Bayou, and communicating with the river by a break in the levee about one-half mile above New Carthage. General Osterhaus reports that this channel offers a depth of over 7 feet.
From the above, it seems that no water is received into Roundaway Bayou from the water passing through Tensas and Macon Bayous and the net-work of bayous connected therewith. I send herewith a sketch,* showing where the water sill pass into the bayou from the river. The channel has been dug by the troops as far as practicable; a depth of 7 feet has been reached between the main level and the back-water by the aid of the steam-pump. The balance of the work to the bayou will have to be done by the dredges. The levee could be cut this day, but is delayed in order to raise portions of the road from Milliken's Bend to Richmond, which might otherwise be flooded by the influx of water from the river into the low wooded land when the levee is cut. Three companies of Bissell's engineer regiment and three pioneer companies, under Major Tweeddale, are employed clearing the bayou from Cooper's plantation to Hecla Place. This portion of the work it is hoped will be completed tomorrow. Colonel Pride has general charge of canal and bayou operations. The levee of the old canal has broken close to the main levee; the break from 30 feet has increased to over 400 feet in width.
Captain Kossak is constructing four casemate batteries in the levee opposite Vicksburg. Two casemates had been erected by Colonel Bissell, which, on inspection, I found it advisable to alter.
I am, general, very respectfully, your obedient servant,
FREDERICK E. PRIME,
Captain of Engineers.
Brigadier General JOSEPH G. TOTTEN, Chief Engineer of the Army.
HEADQUARTERS DEPARTMENT OF THE TENNESSEE,
Milliken's Bend, La., April 18, 1863.
GENERAL: I have the honor to report the following operations since my last, of 11th instant: The main levee was cut on the 13th. During the twenty-four hours subsequent the water at Hecla Place rose over 8 inches, and has been slowly rising since, though I am not informed of the rate. The rise has not been as great as I expected, but will increase when the channel is deepened through to the bayou so as to guide the current, and when the bottoms are filled. All the pioneer companies available have been put to work on clearing the bayou. Major Tweeddale reports that Bissell's four engineer companies and Spicer's pioneer company will have cleared the bayou to Richmond (to the prescribed width) by the 20th or 21st. Colonel Pride will start tomorrow morning, with a small steamboat, for Richmond. Two, and if possible three, barges, of from 100 to 120 [feet] in length, will be passed into the bayou at the same time, with pioneers on them, provided with saws to cut 6 feet under water, and other tools necessary. They will clear out any