Largest Reservoirs in Iowa

Iowa has 4120 dams with recorded storage capacity. The largest is Saylorville Dam with 641,000 acre-feet of maximum storage. One acre-foot equals about 326,000 gallons — enough to supply roughly two households for a year.

#	Dam	County	Max Storage (acre-ft)	Height (ft)	Purpose	Year
1	Saylorville Dam	Polk	641,000	125	Flood Risk Reduction	1975
2	Rathbun Dam	Appanoose	552,000	100	Flood Risk Reduction	1969
3	Mississippi River Lock And Dam 10	Clayton	212,000	43	Navigation	1937
4	Mississippi River Lock And Dam 13	Whiteside	192,000	44	Navigation	1939
5	Mississippi River Lock And Dam 11	Dubuque	170,000	43	Navigation	1937
6	Mississippi River Lock And Dam 12	Jo Daviess	92,000	44	Navigation	1938
7	Mississippi River Lock And Dam 18	Des Moines	90,000	41	Navigation	1937
8	Mississippi River Lock And Dam 16	Muscatine	88,000	34	Navigation	1937
9	Mississippi River Locks And Dam 14	Scott	82,000	39	Navigation	1939
10	Lake Panorama Dam	Guthrie	60,200	70	Recreation	1969
11	Mississippi River Lock And Dam 17	Mercer	50,000	47	Navigation	1939
12	Desoto Dam	Pottawattamie	45,400	25	Fish and Wildlife Pond	1960
13	Little River Watershed Site M-1	Decatur	32,650	61	Flood Risk Reduction	1984
14	Brushy Creek Dam	Webster	31,645	100	Recreation	1998
15	Mississippi River Locks And Dam 15	Scott	30,000	41	Navigation	1934
16	Three Mile Reservoir Dam	Union	29,950	63	Flood Risk Reduction	1995
17	Lake Macbride Dam	Johnson	28,000	56	Recreation	1930
18	Big Creek Diversion Dam	Polk	27,500	80	Flood Risk Reduction	1970
19	Big Creek Terminal Dam	Polk	27,500	95	Flood Risk Reduction	1972
20	Twelve Mile Creek Watershed Site M-1	Union	27,200	66	Flood Risk Reduction	1983
21	Lake Icaria Dam (site M-1-a Walters Cr)	Adams	25,310	56	Flood Risk Reduction	1974
22	Roberts Creek Dam	Marion	21,863	60	Recreation	1968
23	Lake Sugema Dam	Van Buren	21,570	50	Recreation	1992
24	Rock Creek Dam	Jasper	13,700	33	Recreation
25	Lake Sundown Dam	Appanoose	12,640	51	Recreation	1976
26	Sun Valley Lake Dam	Ringgold	11,940	67	Other	1971
27	Pleasant Creek Lake Dam	Linn	11,000	73	Flood Risk Reduction	1977
28	Badger Creek Watershed Site M-1-a	Madison	10,950	46	Recreation	1980
29	Black Hawk Lake Dam	Sac	10,500	12	Flood Risk Reduction	1916
30	Lake Delhi Dam	Delaware	9,920	55	Recreation	1922
31	Cedar Rapids Milldam (5 In 1)	Linn	9,843	16	Hydroelectric	1978
32	Lake Darling Dam	Washington	9,823	47	Recreation	1950
33	West Lake Dam	Clarke	9,675	58	Water Supply	1935
34	Lost Grove Lake	Scott	9,595	75	Recreation	2012
35	Virden Creek Dam	Black Hawk	8,300	39	Flood Risk Reduction	1979
36	Lake Belva Deer Dam	Keokuk	8,100	55	Recreation	2001
37	Wayne Co. Roadgrade Dam 21-67-22	Wayne	7,900	42	Other	1996
38	Lake Wapello Dam	Davis	7,610	57	Recreation	1934
39	Trumbull Lake	Clay	7,250	12	Recreation
40	Green Valley Lake Dam	Union	6,830	41	Recreation	1953
41	Prairie Rose Lake Dam	Shelby	6,824	55	Recreation	1960
42	Maffitt Reservoir Dam	Dallas	6,700	79	Water Supply	1944
43	Little River Watershed Site 65	Decatur	6,700	45	Flood Risk Reduction	1987
44	Geode Lake Dam	Des Moines	6,200	59	Recreation	1949
45	Easter Lake Dam	Polk	6,200	43	Recreation	1967
46	Big Hollow Dam	Des Moines	5,942	60	Recreation	2008
47	Lake Ponderosa Dam	Poweshiek	5,850	50	Other	1969
48	Nashua Milldam	Chickasaw	5,242	20	Recreation	1917
49	Ottumwa	Wapello	5,000	16	Hydroelectric	1960
50	Iowa Falls Milldam	Hardin	4,751	26	Hydroelectric	1925

← All dams in Iowa · Largest reservoirs nationwide