Lemon Dam


Lemon Dam is a zoned earthfill structure with a structural height of 284 feet and a crest length of 1,360 feet. The dam embankment has a maximum base width of 1,170 feet, a crest width of 30 feet, and contains a volume of 3,042,000 cubic yards of earth and rock materials.

The spillway is on the right abutment of the dam and consists of an approach channel, concrete inlet structure, concrete ogee crest section, open concrete chute, concrete stilling basin, and outlet channel discharging into the Florida River. The design capacity of the spillway is 9,600 cubic feet per second.

The outlet works is also in the right abutment of the dam and consists of an approach channel, a concrete intake structure, and a concrete-lined tunnel gate chamber for two 2.25-foot-square high pressure gates. The 9-foot horseshoe-shaped tunnel has a design capacity of 910 cubic feet per second.

Lemon Reservoir is approximately 0.5 mile wide and 3 miles long with a surface area of 622 acres. The total capacity is 40,146 acre-feet, of which 39,030 acre-feet are active conservation.


Lemon Dam is constructed on bedrock of the Cutler Formation (Lower Perian) consisting of red to gray calcareous siltstone, shale and sandstone with interbedded limestone.  The bedrock is highly fractured and fissile and the shale interbeds readily slack when exposed to air.  The dip of the bedrock beneath the dam is approximately 10 degrees to the south.  Reconstruction drill hole data indicates that some of the limestone intererbeds contain solution channels.  Foundation treatment consisted of a grout curtain, with a minimum depth of 160 feet across the valley floor and up both abutments, and a cutoff trench (1.5:1 side slopes) within the limits of the Zone 1 core and extending 5 feet into bedrock or to a minimum base depth of 30 feet.  The trench was excavated to a 10-foot width in siltstone below the old river channel at elevation 7,883.  The reservoir is in a narrow valley that is approximately half a mile wide and three miles long.  It has a maximum storage capacity of 40,146 acre-feet with a surface area of 622 acres at a water surface elevation of 8,148 feet.  The reservoir appears to be watertight since the siltstone and shale bedrock and randomly sorted glacial till are relatively impervious.  Several northwesterly trending normal faults, downdropped to the north have been identified around the edge of the reservoir.  There are no topographic of glomorphic indications that these faults are active.  Where observed, the fault planes are tight and filled with a clay gouge that restricts the movement of water from the reservoir.

RegionFacilities in Upper Colorado | Upper Colorado Home Page
CountyLa Plata
Dam Type
WatercourseFlorida River
Original Construction1961-1963
Modified Construction
National ID NumberCO01688
Hydrologic Unit Code

Structural Height284.0 ft
Hydraulic Height (Normal Operating Depth at Dam)209.0 ft
Top Parapet (Elevation)
Spillway Crest Elevation8167.0 ft
Crest Elevation8167.0 ft
Crest Length1360.0 ft
Crest Width
Base Width
Volume of Dam Construction Materials3,042,000 cu. yards
Streambed at Dam Axis7952.0 ft
Top of Exclusive Flood Control Pool (Elevation)
Top of Joint Use Pool (Elevation)
Top of Active Conservation Pool (Elevation)8148.0 ft
Top of Inactive Conservation Pool (Elevation)8023.0 ft
Top of Dead Storage Pool (Elevation)8005.0 ft

Hydraulics & Hydrology
Total Water Storage at Elevation
Maximum Water Surface Elevation8161.0 ft
Normal Water Surface Elevation
Spillway Type
Auxiliary Spillway
Spillway Capacity at Elevation9600 cfs at 8161.0 ft
Auxiliary Spillway Capacity at Elevation
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation 900 crs @ 8161.0 ft
Diversion Capacity at Elevation
Drainage Area69.0 sq mi
Hydrometeorological Report (HMR)HMR 49
Probable Maximum Flood (PMF) Report

Contact Information
Title Area Office Manager
Organization Western Colorado Area Office- Durango
Address 185 Suttle Street, Suite 2
City Durango, CO 81303
Phone (Office) 970 385-6500
OrganizationFlorida Water Conservancy District
Address1523 County Rd 243
CityDurango, CO 81301
Phone (Office)970-247-5332

Last updated: Mar 05, 2009