Decorative & Drainage Aggregate
Unwashed River Rock
Colorado Smooth Stone · Antero Pit, Park County · Four Sizes · Unwashed · Wash On-Site for Landscape Finish
Retail Price
$40/ton
All four sizes — same price
¾" · 2" · 2–4" · 4–8"
Four sizes available
What Is River Rock?
River rock has spent millennia tumbling through moving water — grinding against other stones, grinding against bedrock, losing every sharp edge until what remains is a smooth, rounded, polished stone with the quiet beauty of something genuinely shaped by its environment.
MCG's river rock comes from our Antero Pit in Park County, sourced from ancient alluvial deposits carried downstream by the South Fork of the South Platte River. These stones — granite, gneiss, quartzite, and other Precambrian crystalline rock from the mountains above South Park — have been water-polished over thousands of years. Their smooth surfaces, natural earth tones, and rounded forms are what Colorado landscapes naturally look like, because they literally are Colorado's natural landscape.
Available in four sizes — ¾", 2", 2–4", and 4–8" — and priced at a flat $40 per ton for all sizes, river rock is one of the most versatile and visually rewarding materials MCG carries.
The Antero Pit — Park County, Colorado
The Antero Pit sits near Antero Reservoir, Denver Water's first collection reservoir on the South Platte River. The bedrock geology of this region is ancient Paleoproterozoic biotite gneiss and granite porphyry, formed deep in the earth's crust some 1.7 billion years ago. At roughly 8,900 feet elevation, the Antero Pit is a remote, unmanned site — material is available exclusively through MCG's commercial trucking fleet.
Unwashed River Rock — Antero Pit, Park County CO · As Delivered
Four Sizes — One Price
All four river rock sizes are available at $40 per ton. Selecting the right size is about matching the rock to both the function and the visual scale of your project.
- ¾" River Rock — The most versatile size. Fine enough to nestle comfortably underfoot on garden paths, yet substantial enough to stay put in moderate runoff. Ideal for decorative ground cover in planting beds, around specimen trees, and as a mulch substitute in xeriscape gardens. One ton covers approximately 110–130 sq ft at 3" depth.
- 2" River Rock — The most popular all-purpose decorative size. Bold enough to create visual impact, small enough to handle easily. Perfect for dry creek beds and swales, drainage ditches, garden bed edging, water feature surrounds, fire pit areas, and dog runs. One ton covers approximately 90–110 sq ft at 3" depth.
- 2" to 4" River Rock — Statement-scale stone that commands attention in the landscape. Best suited for high-flow drainage channels, larger dry creek beds, natural borders, and erosion control on slopes. One ton covers approximately 65–80 sq ft at 3" depth.
- 4" to 8" River Rock — The heaviest and most dramatic of the four sizes — individual stones up to the size of a cantaloupe. Used for large-scale dry creek beds, culvert outlet protection, heavy erosion control on steep slopes, and as accent boulders nestled into planting beds. One ton covers approximately 40–55 sq ft at 4" depth.
Pro Tip — Mixing Sizes
The most natural-looking river rock installations use two or three sizes together — just as a real riverbed would. Consider anchoring a dry creek bed with 4–8" stones at the channel center and edges, filling the middle with 2–4", and finishing with 2" for a realistic graded appearance.
Unwashed River Rock — Medium Size · Antero Pit, Park County CO · As Delivered
Where Is River Rock Used?
River rock's combination of natural beauty, durability, and functional drainage properties makes it one of the most widely used decorative aggregates in Colorado mountain landscaping.
- Dry Creek Beds & Drainage Swales — A dry creek bed guides stormwater and snowmelt across a property in a channel that looks like it was always there. River rock's smooth rounded form, earth tones, and size variety create a convincing natural appearance while performing genuine water management work.
- Xeriscape Ground Cover — River rock as a mulch substitute never decomposes, never blows away, requires no annual replacement, and pairs beautifully with native grasses, sedums, ornamental grasses, and drought-tolerant perennials.
- Decorative Planting Bed Mulch — Spread 2–3 inches deep over landscape fabric in planting beds, ¾" and 2" river rock suppresses weeds, retains soil moisture, and gives beds a clean, permanent finish.
- Water Features & Pond Surrounds — River rock is the natural choice for lining the perimeter of ponds, fountains, and recirculating water features. Its water-polished appearance is authentic, its colors deepen beautifully when wet.
- Foundation & Downspout Drainage — A splash pad of 2–4" river rock beneath roof downspouts absorbs the energy of falling water, prevents soil erosion, and directs runoff away from the foundation.
- Erosion Control on Slopes — On sloped areas subject to runoff erosion, the 2–4" and 4–8" sizes provide enough mass to hold position through Colorado's heavy spring snowmelt and monsoon rain events.
- Dog Runs & Outdoor Living Areas — River rock's smooth surface is comfortable for dog paws and drains quickly, making it an excellent alternative to muddy grass or hard pavement in dog run areas.
Unwashed River Rock — Antero Pit, Park County CO · Natural Fines Present
How to Wash River Rock On-Site
MCG's river rock arrives unwashed — natural fines and surface dust from the pit are present on and between the stones. For drainage and erosion control applications this makes no difference. But for high-visibility decorative work — a dry creek bed in a front yard, a water feature surround, a xeriscape garden — washing the rock before or after placement transforms the appearance. The stones' true colors emerge, the surface takes on the polished sheen of a natural riverbed, and the finished installation looks like it was built with premium landscape-grade material.
Washing is straightforward and requires no special equipment beyond a garden hose with a spray nozzle or a pressure washer.
- Method 1 — Wash Before Spreading (Best for Smaller Quantities) — Place the rock in a wheelbarrow, large tub, or on a tarp. Spray thoroughly with a garden hose, agitating the stones with a shovel or by hand. Let the dirty water drain off, then spread the clean rock. This gives you the most control and the cleanest result, but is labor-intensive for large areas.
- Method 2 — Wash In Place (Best for Large Areas) — Spread the rock to its final depth and position, then flood the entire area with a garden hose on a wide-spray setting. Work in sections, moving the spray slowly across the surface. The water carries fines down through the rock and into the soil below. Repeat once or twice until runoff runs clear. This is the fastest method for large installations.
- Method 3 — Pressure Wash In Place (Best Finish Quality) — After spreading, use a pressure washer at low-to-medium pressure (1,200–1,800 PSI) to blast fines off the stone surfaces. Work in overlapping passes. This produces the cleanest, most vibrant finish — colors deepen noticeably and the stones take on a wet-look sheen even when dry. Ideal for front-yard showcase installations.
- Timing Tip — If you are placing rock around plants or over landscape fabric, wash in place after spreading. Washing before placement and then walking on the rock to spread it will re-coat the stones with soil from your boots and tools.
- Water Runoff — The wash water will be turbid (muddy) and will carry fine sediment. Direct runoff away from storm drains, paved surfaces, and neighboring properties. Letting it soak into a lawn or garden bed is fine — the sediment is inert mineral material.
What to Expect After Washing
Freshly washed river rock from the Antero Pit reveals a striking palette of warm grays, tans, rusty reds, and occasional white quartz veining — the natural color signature of South Platte granite and gneiss. Colors are most vivid immediately after washing and settle to a slightly more muted dry tone, but remain far more vibrant than unwashed material.
Unwashed River Rock — Large Rounded Stones · As Delivered
Ordering from the Antero Pit — What You Need to Know
The Antero Pit operates differently from MCG's main Divide pit, and understanding these differences before you order will make the process smooth.
- Unmanned Pit — The Antero location is not staffed. There is no walk-in service, no retail counter, and no drive-up loading for customers.
- No Private Trailers or Pickup Trucks — The pit cannot load personal vehicles, pickup truck beds, or privately owned trailers regardless of size. Material is exclusively loaded onto heavy commercial transport.
- MCG Delivery Available — We regularly dispatch our End Dump and Tandem trucks to the Antero Pit to fulfill customer orders. Same-day delivery may be available depending on your project's distance from the pit — call Tess to confirm scheduling.
- Unwashed Material — River rock from the Antero Pit is not washed. Fines and non-organic debris may be present on and between the stones. This is consistent with naturally sourced aggregate and has no meaningful effect on decorative or drainage performance.
Antero Pit — Ordering & Delivery
The simplest path for most customers: call Tess at (719) 686-1566, tell her the size(s) and quantity you need, and she will schedule an MCG truck to load at Antero and deliver direct to your project site.
Unwashed River Rock — Small Mixed Sizes · As Delivered
Coverage Reference by Size
| Size | Approx. Dimension | Best Use | Coverage @ 3" Depth |
|---|---|---|---|
| ¾" | ~½" – 1" | Ground cover, garden paths, xeriscape, bed mulch | 110–130 sq ft/ton |
| 2" | ~1½" – 2½" | Dry creek beds, drainage, water features, dog runs | 90–110 sq ft/ton |
| 2–4" | ~2" – 4" | Drainage channels, downspout pads, slope erosion control | 65–80 sq ft/ton |
| 4–8" | ~4" – 8" | Heavy erosion control, culvert outlets, accent boulders | 40–55 sq ft/ton (@ 4" depth) |
Order Unwashed River Rock
Call Tess to place your order, confirm availability, and schedule delivery.
Antero Pit — unmanned. No drive-up service. MCG delivery is the standard option for most customers.