Yard Drainage in Cayucos

Paso Robles Landscaping plans and installs drainage for Cayucos yards: regrading around foundations, trench drains at low garages, downspout lines, swales that catch water from the street edge or the lot above, rock-lined outlets, and soakage where the sand allows it. Cayucos has no city government. It is an unincorporated town inside the Coastal Zone, and drainage questions go to the County of San Luis Obispo, through Title 23 of the County Code (its coastal zoning rules), the Estero Area Plan and County Public Works. Much of the town was built before anyone required curbs or storm drains, and that history explains most of the wet yards we see here. Call 805-712-4440 to set up a visit, or write to us through the contact form.

This guide is about handling storm runoff on private Cayucos property. Planting, irrigation and other yard projects here are on our Cayucos landscaping page. Morro Bay, a few minutes south, is a city with its own rules, covered in our Morro Bay drainage guide. For a deeper look at the County grading and drainage-plan sections that apply all along the coast, the Avila Beach drainage guide walks through them section by section.

What County Documents Say About Cayucos Drainage

Every row cites a paper from San Luis Obispo County government or the Cayucos Sanitary District, read October 24, 2026.

Drainage Fixes We Build on Cayucos Lots

Most Cayucos problems come down to one of three things: water arriving from somewhere else, a house that sits lower than the water around it, or a slope that moves water too fast. We usually combine a few of the measures below and start with the simplest.

• Reshaping the ground beside the house so it sheds water outward, plus a raised landing or threshold where a garage or door sits low
• Trench drains across the bottom of a driveway that drops toward the garage, piped to a safe spot on your own lot
• Downspouts carried by solid pipe or surface channel into planting beds, gravel strips or a lawn edge instead of against the foundation
• Shallow cross swales and low berms inside your lot line that catch water coming off the street edge or a higher lot and turn it along the slope
• Cobble-lined channels and rock at every pipe outlet, so concentrated flow does not dig a gully
• Gravel infiltration trenches and rain gardens where a soak test says the sand will take water, kept clear of footings
• Gravel, decomposed granite and open-jointed pavers rather than fresh solid paving for walks, narrow side yards and a parking spot
• Area drains and catch basins with solid pipe and cleanouts, so silt can be flushed out before winter
• Mulch, coir netting, fiber rolls and native seed on any soil we disturb, in place before the first storm

The County study notes that the sands under parts of Cayucos once soaked up rain fast enough that little ran off. That is still true on some lots and long gone on others, where fill, clay or heavy compaction have changed the ground. A test hole is dug and timed to see how quickly it drains before anything that depends on infiltration is designed.

Why So Much of Cayucos Drains Across Yards

The Cayucos Drainage and Flood Control Study was prepared for the County Flood Control and Water Conservation District after residents reported flood damage in the heavy rains of March 2001, and published in 2003. It explains that drainage pipes and flood control were not built in as the town grew. Early development came before Subdivision Map Act requirements, curbs and gutters were not required, and the sandy soil, the slope toward the ocean and the four creeks made a storm drain system seem unnecessary. As roofs and paving spread, more water ran off and less soaked in.

The result, in the study’s words, is that storm water in most areas travels as surface runoff in streets, ditches and back yards. The town was split into 21 drainage zones. The four largest follow Cayucos Creek, Little Cayucos Creek, Old Creek and Willow Creek, and most of the smaller zones send water straight toward Estero Bay through overland flow or outfalls, many of them along Pacific Avenue and Studio Drive at the public beach access points. The study proposed pipelines and inlets for many zones, but under a long-standing County policy the District does not pay to build community-specific fixes; the property owners who benefit have to agree to fund them. So for most lots, the drainage plan is still whatever the owner builds.

Houses That Sit Below the Street

This is the classic Cayucos problem. When a home sits lower than the road and the driveway slopes down toward the garage, the driveway becomes a channel. The study describes street water reaching residential lots through the dip in the curb at driveway entrances, and runoff ending up in garages and homes. Its recommendations for new homes were a finished floor and garage at least one foot above the adjoining street grade, driveways that slope down away from the house toward the road, and a County standard mountable berm at driveways that sit below the edge of pavement. Those are recommendations from the study, not code by themselves, so we treat them as good practice and confirm with the County what applies to a given permit.

The study also looked at rolled asphalt berms along the road edge. It found some existing ones only 2 to 3 inches tall, recommended a Caltrans Type E4 mountable berm at least 6 inches above the gutter flowline where a berm is needed, and warned about the downside: berms keep water in the street, so the total volume grows downstream, a berm overtops once it fills, and a berm built in front of one house can push water onto the neighbors. Anything built in the road strip falls inside the County right of way, covered further down.

On the private side we can do a lot. A trench drain across the low end of the driveway, a slightly raised apron or landing at the garage door, regrading so the side yards fall away from the walls, and a solid pipe carrying that water to an outlet that will not just send it back toward the house. Where the lot is lowest of all, we look for room to hold water in planted beds or a shallow basin, with a surface overflow path planned for the storms that exceed it.

Uphill Neighbors and Downhill Neighbors

A theme runs through the study’s neighborhood findings: many reported problems were caused by residents blocking historical drainage courses or removing drain lines that carried water from higher lots down toward the street. When a drain line is filled in or pulled out, water ponds in the back or side yard of the property above. The District discourages filling drainage courses or removing drain pipes and asks neighbors to keep runoff moving freely down to the street. The same study says owners are the ones responsible for keeping natural or built drainage channels on their land clear of fallen trees, debris and sediment, because the County does not maintain facilities on private property.

County Public Improvement Standards point the same way. Section 5.1.3 says water is to be received and released in substantially the same location and at the same velocity as before, unless a comprehensive drainage plan calls for a change and the affected properties are protected at least as well as before. For County-approved improvement plans, Section 5.1.4(F) expects a recorded easement and the adjacent owners’ written approval where a minor drainage improvement falls on a neighbor’s property. When we find an old pipe crossing a property line, we trace where it starts and ends before anything is cut, removed or reconnected, and we keep the path that the uphill lot depends on.

Creekside Lots Along Cayucos, Little Cayucos, Old and Willow Creeks

The Estero Area Plan places all four creeks and their tributaries in its Flood Hazard combining designation and says these flood-prone natural drainage courses should stay in their natural state to protect native plants and wildlife. It describes the floodplains of Cayucos Creek, Little Cayucos Creek and Willow Creek as limited to land right next to the channels and estuaries, and notes that areas along Old Creek would flood if Whale Rock dam failed. The plan’s coastal stream setbacks, measured from the upland edge of riparian vegetation or from the top of the bank where there is none, are 25 feet on Cayucos Creek, 20 feet on Little Cayucos Creek, 50 feet on Old Creek and 20 feet on Willow Creek inland of Ocean Boulevard.

The study adds the street-level picture. The worst flooding in town is in the Cayucos Creek floodplain west of Highway 1, around B Street and Ash Street, where the creek overtops its banks and local drainage cannot get into the creek while the water is high. The Old Creek 100-year flood stays inside the channel banks because Whale Rock Dam softens the peak upstream. Under Public Improvement Standards 5.1.3(D), no work happens in a natural watercourse without the needed State and Federal permits, for example from the state wildlife agency or the Central Coast regional water board. On creekside lots we keep outlets, rock and fill out of the setback, run the plan past County Planning first, and plan for the yard to get wet in a big storm rather than promising it never will.

Bluff-Top and Beachfront Lots

Along Pacific Avenue, Studio Drive and the Ocean Front, the plan’s Cayucos setback table puts bluff-top setbacks at 25 feet minimum, and more where needed to withstand bluff erosion over a 100-year period. The plan’s shoreline development standards ask applicants building on or next to a beach or bluff for a preliminary drainage, erosion and sedimentation plan showing that no soil or materials will be stockpiled on the beach, that erosion and runoff controls go in at the end of each work day, that construction debris leaves the beach daily, and that no machinery enters the intertidal zone. The plan also identifies a high liquefaction potential along parts of the creeks, some bluffs and the shoreline in town.

The ordinance rule on bluff outfalls is strict, as the table above shows, so we design bluff-side yards to keep water away from the edge: planting and gravel that slow it down, roof water collected near the house, and overflow sent toward the street frontage. Nothing is built inside the bluff setback without a site-specific sign-off from a geologist or engineer.

Hillside Lots and the Eastern Slopes

The Estero Area Plan places the hillsides above Cayucos in a Geologic Study Area for landslide risk, and within the urban area it requires a geologic report by a certified engineering geologist for hillside development proposals. Its drainage section calls for the cumulative drainage and geologic effects of building on the eastern slopes to be studied and handled on an areawide basis. Public Works also adds a drainage and flood check to building permits where the ground slopes 10 percent or steeper.

East of Highway 1, outside the urban reserve line, the County’s Cayucos hillside FAQ explains that the Morro Strand and Morro Rock View hillside lots are zoned Rural Lands, sit in a Geologic Study Area, and lack community water and sewer. Grading there on ground steeper than 10 percent brings environmental study, past 20 percent a public hearing, and past 30 percent a variance. On any sloping Cayucos lot our approach is the same: slow the water down with cross swales and rock, keep the soil covered, and never send concentrated flow down the hill toward the neighbor below.

Pacific Avenue and Studio Drive Neighborhoods

The Estero Area Plan treats two areas as Community Small Scale Design Neighborhoods: the Pacific Avenue neighborhood and the Studio Drive neighborhood between Highway One and the ocean. Applications for new development there must include a topographic map showing the elevation of the fronting street, the site contours, and existing and proposed drainage patterns. Development within 100 feet of a wetland, estuary or stream, or within 300 feet of the ocean bluff-top, goes through a Minor Use Permit. If you are remodeling in one of these neighborhoods, the drainage pattern is part of the application, and we can help map how water moves across the lot today.

The Street Edge, Curbs and County Permits

Many Cayucos streets have no curb at all. The plan waives curb, gutter and sidewalk requirements in mapped parts of town except where the County Public Works Department determines they are needed for drainage, and the study recommended that infill on streets that already have curbs add curb and gutter so the system stays continuous. Where a sidewalk exists, the Public Improvement Standards bar concentrated flow across its surface; the D-4 sidewalk underdrain drawing shows a cast iron conduit at least 3 inches tall and 5 inches wide, set flush with the curb face, half an inch above the gutter flowline, and no closer than 5 feet to a driveway.

Digging, pouring or placing anything on County road land calls for an encroachment permit, applied for online in Citizens Connect. Public Works gives a typical turnaround of 5 to 7 business days, though complex requests take longer; the fee is paid and an on-site or phone meeting with the County inspector happens before any digging, and a closing inspection compares the finished work with the County standards. The County application adds that road-strip work must be performed by a suitably licensed contractor who carries a bond and sets up traffic control.

Our stopping point: Our work covers the drainage inside your lot lines and ends at the property line. A curb core, sidewalk underdrain, berm or pipe in the road strip goes to a contractor whose license and permit the County accepts for that work, and our pipe ends at an elevation and grade that piece can accept, so the two connect cleanly. For questions about your own street, Public Works is at 805-781-5252.

Keep Yard Water Out of the Sewer

The Cayucos Sanitary District handles sewer service in town. Section 28 of its primary ordinance bars anyone from discharging storm water, surface water, groundwater, roof runoff or subsurface drainage into a sanitary sewer, and its lateral ordinance makes the owner responsible for the private lateral from the building wall to the main, including keeping it free of the cracks and open joints that let rain and groundwater in. A downspout or French drain tied into a sewer cleanout is exactly what those rules forbid. When we find one, we disconnect it and send the water to planting or a proper outlet, and we locate the lateral before any trench goes in.

Rain Barrels, Rain Gardens and Pool Water

A County Public Works factsheet on rain barrels says no permit is required for rain storage totaling 360 gallons or less, used outdoors. Its homeowner rainwater guide places rain gardens 10 feet or more away from foundations, keeps them on ground flatter than 15 percent, clear of leach fields and shallow utility lines, and expects them to drain within 72 hours or get an underdrain. On the sandier lots near the beach those numbers are easy to meet; on low lots with slow soil, we skip the rain garden and use surface storage instead.

For pools and spas, the pool drainage factsheet favors letting dechlorinated water seep gradually into garden beds on the same parcel, with none of it running off the property, and requires a call to your sewer provider before any water goes to the sanitary sewer; for most of town that is the Cayucos Sanitary District. Water from a saltwater pool is not allowed in either the sanitary sewer or the storm drain. Public Works’ home stormwater FAQ also names a County native seed blend of short, low fire risk plants meant to hold exposed soil in place.

Water Supply and Irrigation Runoff

According to County Public Works’ CSA 10/10A page, the town’s tap water starts in Whale Rock Reservoir, is cleaned at the Cayucos Water Treatment Plant, and then reaches homes through one of three separate water systems: two mutual water companies and a County-run service area at the south end. Each sets its own customer rules, so check with the company on your bill about current watering limits. Overwatering is one of the quiet causes of wet yards and soggy slopes, so part of every drainage job is adjusting the sprinklers and drip so they stop adding water where we are trying to remove it.

Rainy Season and Call 811

Under the Coastal Zone ordinance, permitted grading that happens in the wet months from mid-October to mid-April, or sits unfinished through them, needs an approved plan for controlling erosion and sediment. On small jobs with no permit involved, we likewise schedule digging for dry spells, protect the nearest street drain or ditch, cover spoil piles and mulch or seed new soil before rain. Before any trench, we call the regional notification center at 811; as the state contractors board (CSLB) notes, excavators must notify it ahead of digging, and we dig by hand close to the paint.

Steps in a Cayucos Drainage Project

1. Look at the water. Ideally during or just after rain, we note where water enters the lot, where it stands, how the house sits compared with the street, and what lies uphill and downhill.
2. Check the constraints. Creek setbacks, bluff edge, slope, flood hazard mapping, old pipes and the sewer lateral, plus whether a County permit is likely.
3. Soak test and spot elevations. How fast the ground drains, and the fall from the slab to the lowest corner and out to the road.
4. Sketch the plan. Every route water takes, which part is kept on the lot, which part leaves and where, and which pieces need the County or a licensed engineer or geologist.
5. Build. Erosion controls first, then grading, drains, pipe and cleanouts, and finally rock, plants and mulch.
6. Flow test and handoff. Water goes through each inlet while you watch, and you keep a marked-up sketch of every line and cleanout.

Who to Call in Cayucos

• County Public Works (road strip, encroachment permits, drainage and flood questions): 805-781-5252, or email the encroachment desk listed on the Public Works permit page.
• County Planning and Building (coastal, grading and building permits): 805-781-5600, with applications filed online in PermitSLO.
• Cayucos Sanitary District (sewer laterals, pool drain-down to sewer): 200 Ash Avenue; 805-995-3290.
• Your water purveyor: listed on your water bill.
• Underground lines: dial 811 first.

Contractor license: CSLB #986950. The text on this page is our plain-language summary of County and Sanitary District papers, written to help you get ready. Treat it as background, never as a legal opinion, an engineered design or a geologic finding; our crew does not work for the County and includes no civil engineers or geologists. Recommendations from the older drainage study are labeled as such and are not current law. Permits, setbacks and coastal calls belong to the County, stamped design comes from a licensed professional when a job needs it, and road-strip work needs its own County encroachment permit. If the documents leave a point open for your lot, we put the question to the County in writing first.

Related Guides for the North Coast and Beyond

More North Coast pages, plus drainage guides written for other towns:

• Cayucos landscaping
• Morro Bay drainage guide
• Avila Beach drainage guide
• Pismo Beach drainage guide
• Grover Beach drainage guide
• Oceano drainage guide
• Cambria concrete flatwork
• Cambria hardscape
• San Luis Obispo drainage guide
• Retaining walls
• Mulch and rock installation

The full town list lives on our service area page.

Frequently Asked Questions

Why does water run into my garage in Cayucos?

Many Cayucos homes sit below the street, and a County drainage study found that street runoff can turn in at the lowered curb of a driveway that slopes down toward the house. A trench drain across the driveway, a slightly raised apron at the door and regrading on your side usually help. A berm out in the road strip is on County land and needs a County permit, built by a contractor the County approves for that work.

My uphill neighbor’s water floods my yard. What can be done?

The County study found that many problems in Cayucos began when drainage courses were blocked or old drain lines were removed. County improvement standards expect water to leave a site in roughly the same place and at the same speed as before. We trace the existing paths, then build swales and pipe on your lot that carry the water through without pushing it onto the next lot down.

How close to Cayucos Creek can I build drainage?

The Estero Area Plan sets coastal stream setbacks of 25 feet on Cayucos Creek, 20 feet on Little Cayucos Creek, 50 feet on Old Creek and 20 feet on Willow Creek inland of Ocean Boulevard, measured from the upland edge of riparian vegetation or the top of the bank. Work in the creek itself needs State and Federal permits. County Planning gets a call from us before anything near a creek is drawn up.

Can I connect my downspouts to the sewer cleanout?

No. Cayucos Sanitary District Ordinance 5 prohibits discharging storm water, roof runoff, groundwater or subsurface drainage into the sanitary sewer. Roof water should go to planting, a soak trench where the soil allows, or an approved outlet.

Will you put the drain through the curb too?

No. Our crew handles everything up to the property line. A curb outlet, sidewalk underdrain or berm sits on County road land, so the County has to issue a permit for it, and the work goes to a contractor it will allow in the road. Our pipe is set so that piece can tie straight in.