Gross Reservoir

UPDATE:  Starting in 2022, reservoir expansion is underway.  Click here for updated post on Gross Reservoir recreation during construction.

Gross Reservoir is a great metro-area paddling destination in the foothills above Boulder.  The lake is non-motorized and is popular with kayaks and duckies as well as stand-up paddleboards.  It is also quite deep (max ~300 feet) and graced by steep, forested slopes around much of its shoreline.

Gross Reservoir

South Boulder Creek Arm

Gross Reservoir is an appealing destination because it's reasonably close to Front Rnage population centers, and has winding inlets and coves that offer protection from winds. It can be accessed via Highway 72 from Golden/Denver or via Flagstaff Road from Boulder.  Gross Dam Road, which is connects the two accesses, is gravel but can be mildly washboardy in places.  Osprey point, the southernmost access point, is probably the most desirable because it offers the best access to the South Boulder Creek arm of  the lake.  On summer weekends, Osprey Point may fill up early.  The South Shore access point is near the dam and has fewer shoreline features and more open water exposure to wind.   

Vicinity Map

    Location info [key]:

    

    Scenery: 4
    Shoreline Interest: 4
    Non-motorized
    Use: High
    Fee: None
    Access: Gravel
    Full elev = 7282; Best near full, 

    significant drawdown possible

    Water level info
    Rec. info

    Weather 

    Rec. map

Denver Water relies heavily on Gross Reservoir to supply the water needs of its customers, which subjects the reservoir to significant water level fluctuations throughout the year.  The lake can draw down substantially in dry years; when at or near full it is quite scenic.  Check Denver Water's website for current status.  95% full or above is great.

☆  South Boulder Creek Arm

☆  Cove on main Reservoir

A great outing from Osprey Point is to paddle westward up the South Boulder Creek Arm.  The well-protected and canyon gradually narrows as it zigzags toward the inlet where South Boulder Creek tumbles into the lake.  This arm often harbors calm waters and sees less wind than the more open areas of the lake.  

Another good outing can be made by exploring any of the small coves in the central portion of the lake.  A longer day can be made by paddling up Forsythe Canyon, the large northern arm of the reservoir.  Be aware that winds can pick up quickly if storm clouds are moving in.  There are also places on the lake where the surrounding topography may obscure a good view of approaching weather.  A check of the hourly forecast is a good idea to minimize the chance of weather surprises.  

South Boulder Creek Inlet

Calm waters in a cove

In the coming years, Denver Water will begin a massive project to expand the dam and reservoir, which will change the setting dramatically.  Stay tuned for updated information on the recreational impacts of this undertaking.  Have fun and stay safe!

Please feel free to add observations of current conditions to the comments!