Getting Started

If you are moving to the Lost Creek Designated Basin you should know about the water resources in the area. If you are a well owner, it is worth your time to understand the geology of the area and the pressure on resources that produce the dynamics of Colorado water resources. The following section is designed to introduce you to the area and groundwater fundamentals, well fundamentals, state law regarding groundwater, and finally our local rule set designed to protect the resource for all users.

Commonly Used Geology Terms

• Aquifer - A geologic formation that contains water in sufficient amounts to be able to be withdrawn from wells drilled into it.
• Bedrock layer - A commonly used term to define the bottom of a ground water system.
• Confining Unit or Layer - A geologic formation that blocks water flow vertically and separates aquifer layers.
• Formation - A geologic term describing a layer or consolidation of material with similar properties.

Big to Small Geology

Lost Creek and Denver Basin Groundwater System

Source: Colorado Groundwater Atlas, 2003, modified by LCGWMD. (Note: While this graphic is a representation of a cross section from NW to SE south of the Lost Creek area, its representation is accurate to Lost Creek Basin geology.)

Pierre Shale Bed

Pierre Shale Wikipedia

Pierre shale bed is part of a large sedimentary deposit left by the western seaway approximately 75 million years ago. The composition of the Pierre shale bed is marine-based with high amounts of bentonite. Bentonite is commonly used as a sealing agent for ditches and ponds since it swells in the presence of water to preclude water passing through it. For this reason, the Pierre shale bed is the “teacup” under the Front Range known as the Denver

Basin that holds the rest of the groundwater system within.

Fox Hills Formation

Fox Hills Wikipedia

Immediately above the Pierre Shale bed is the first water bearing geology known as the Fox Hills Formation. The Fox Hills aquifer system resides in the sandstone geology left by receding waters of the Western Seaway. It is relatively tight-grained sandstone with slow water movement and long recharge times.

Laramie Formation

Laramie Formation Wikipedia

Generally adjoining and normally combined for management purposes with the Fox hills formation is the Laramie Formation. This layer rests on top of the Fox Hills Formation and is a result of more fine-grained sediment settling in later stages. So, there is a lower layer with sandstone and the upper layers are mixed mudstone, clay, and coal, which create the upper confining layer of the system.

Laramie-Fox Hills Formation

Within the Lost Creek basin, the Laramie-Fox Hills formation is a primary source of water for rural domestic wells. Water in this system mostly under Artesian pressure since its recharge points are well above the basin of the formation. Recharge areas are the foothills along the Front Range as well as some tributary contribution from the South Platte River system. Recharge to inner areas of the formation is exceptionally slow even in geological terms. Demand on the aquifer resources are increasing, creating a decline in water levels across the system.

Arapahoe Basin

Arapahoe Basin Wikipedia

The next major layer containing aquifers in the Denver Basin is the Arapahoe Formation. The Arapahoe Formation extends well into the Lost Creek Designated Basin and is another important source of water for rural domestic wells. Its composition is a mixture of sandstone bends and clay or mudstone areas. The Arapahoe aquifer system thins to the north to a line approximately east-west at Keenesburg where its layers emerge at the surface.

Denver Formation

Denver Formation Wikipedia

Above the Arapahoe Formation is the Denver Formation, which should not be confused with the whole Denver Basin. The Denver Formation extends approximately 15 miles into Lost Creek from south to north. It is the first layer created by runoff from the uplift of the Rocky Mountains and contains a mixture of alluvial and fluvial gravels and course sands intermixed with varieties of mudstone. The deepest areas are under the greater Denver area with fans to the north, east, and south. While this aquifer exists in the Lost Creek Basin, the district restricts access to aquifers within due to very low probability of viable water sources.

Dawson Arkose and Castle Rock Conglomerate

Dawson Arkose WikipediaCastle Rock Conglomerate

There are two more formations that complete the Denver Basin – the Dawson Arkose and the Castle Rock Conglomerate. These formations do not lie within the Lost Creek Basin. They may have some contribution to water in the Lost Creek area due to outcrop seep and runoff or hydraulic connectivity within the South Platte River Basin but those are considered minimal if any at all.

Lost Creek Quaternary Alluvium

Alluvium Wikipedia

Source: Lost Creek Aquifer Storage and Recovery Study

The final and uppermost formation in the Lost Creek Basin is alluvial gravel and coarse sands flowing from south to north. This aquifer, known as the Lost Creek Quaternary Alluvium, is the most prevalent and abundant supply of water in the district from year to year. The alluvium provides nearly all ground water irrigation in the basin as well as supplying various commercial and municipal needs through export permissions. The alluvium is primarily large areas of gravel and coarse sand brought down from mountain glacial erosion spread in the ancient beds of Lost Creek and West Sand Creek. In Lost Creek the alluvial aquifer is no longer available for new well permits. The State has declared the alluvium to be over-appropriated. The Lost Creek Groundwater Management District protects senior rights in the alluvium through enforcement of state-sanctioned well permitting, construction, and uses.

Well Fundamentals

If you are new to a groundwater well as your source of water there are some important things to know. The following section introduces some of the lexicon used in well drilling and installation as well as some of the issues affecting water availability and quality.

Responsibility

The first and foremost consideration for a well owner is that there is no water company responsible for the quality and quantity of water available to you. You bear the responsibility to ensure your water source is sanitary and available. If you are in new construction and the well is also new, the licensed driller/installers will ensure your system is built to deliver the water that is available in accordance with your well permit. The quality of the water is a different matter. During installation, the driller/installer will sanitize the well with a chlorine treatment to remove bacteria that may have entered as a function of the drilling and installing processes. The chemical composition of your water will be a function of the aquifer it comes from. Water throughout the Lost Creek basin in the lower aquifers is considered safe for drinking and domestic uses. Alluvial waters are safe in the south half of the basin but progressively get less safe for drinking in the northern half of the basin. This is a result of decades of introduced surface contaminants flowing into the groundwater system. If you have concerns about the quantity or quality of water in your system, please see our section, Driller/Installers Serving the Lost Creek Basin and Residential Well Testing.

Well Permit

If you are moving into a residence with an existing well, it is highly advised to check your well permit details available through the Colorado Division of Water Resources. The permit will detail the depth of the well, the aquifer from which water is extracted, and the permitted amount of water that can be drawn annually also known as your appropriation. Additionally, reputable installers will include an installation report with the permit file. This report identifies the well structure, pump and motor type and capacity, intake level, a drilling log showing core materials by depth, and a drawdown test. The drawdown test shows the drop in water level when water is taken at the permitted rate over a sustained period of time (sustained rate). The drawdown test was a snapshot in time when the well was created. As the well ages the drawdown will change. Changes occur for various reasons but in the next paragraphs we will examine some of them.

Well Construction

Domestic and residential wells permitted in the Lost Creek Basin are now all constructed into confined aquifers (Arapahoe and Laramie-Fox Hills). When the well is drilled, the driller bores into the described aquifer using geological information and confirms correct placement through analysis of the core material log. Once the driller penetrates the upper confining layer of the target aquifer, artesian pressure will force water to rise to the static level of the aquifer system. The drilling continues until the driller reaches the lower confining unit of the aquifer system. A well casing is then placed in the borehole and includes a perforated length within the active aquifer zone and solid casing above to preclude water entry from other sources. The installer may insert filter pack around the perforated section to increase flow into the pump intake. Filter pack is a coarse gravel band around the perforated casing that allows free flow of water and more importantly, creates a larger producing area of the aquifer material around the perforation to enhance the specific capacity of the well. Above the aquifer, the installer must seal or grout the borehole around the casing to prevent contamination from higher layers or surface water.

Well Performance

Specific capacity is a term used by hydrologists to describe a well’s performance as the static level of water in the aquifer it resides in increases or decreases. In the Lost Creek Basin we are mostly concerned with reduced specific capacity due to declines in static levels in all aquifers. In simpler terms, as water levels decline, the head pressure of water in the surrounding aquifer formation pushes less water toward the well. A point of equilibrium will be reached at a particular static level and then pump capacity will overdraw until the intake is exposed. When the intake is exposed, you get no water and the pump and motor are in danger of burning up due to lack of cooling flow around and through them. Clogged perforations or screens in the well casing can also reduce ability of the water to flow into the intake and cause similar problems. As the well ages, smaller particles may infiltrate the filter pack area and/or bacteria may cause calcification on perforations. Both reduce flow over time. When constructing a well, you have choices in equipment and varied costs. Cheaper systems do not protect the pump and motor from loss of pressure. An investment now in a better system can save major expenditures later.

Water Quality

Let’s go back to water quality for a quick discussion on chemical composition and uses. As noted before, deep aquifers are all determined to be safe for domestic uses. That would be you drinking, bathing, watering animals, washing the car, etc. The deep waters have higher dissolved solids (or salts) in their chemistry and are less beneficial for irrigating lawn, trees, shrubs, or that little cash crop you may be contemplating on your parcel.

New Well Construction

Well Construction Decision Making Process

So how much water do you need for your lifestyle in the country? That is a question you must consider carefully before choosing a land parcel to buy or how to apply for water permits if no well exists.

There are three processes you must be familiar with when constructing a new well.

The first is a state-sanctioned determination of water right. The determination of water right is conducted by the Colorado Division of Water Resources and specifies what water is available for use under a particular land parcel. That state uses hydrogeological data to create this right and does not do any physical testing to verify it. A determination of right can be applied for at the state office. Please read Lost Creek guidance here before applying so you can expedite the process. When granted, the right may include separate water quantities from several aquifer layers. Each layer is considered a separate right. They cannot be accessed through a single well. A separate well must be constructed for each layer.

The second process is application for a permit to construct a well. If you already have a determination of right, the permitting process is administrative. If you do not have a determination of right, the state examines the parcels to ensure the right is available for use then issues a permit.

Warning – the determination of water right can be detached from its land parcel above and sold the same as any other property. Make sure your realtor or seller has the correct information before committing to a land parcel and if there is any doubt, seek assistance from the Lost Creek Groundwater Management District or the state DWR office.

The third item is demonstration of water availability to the county you are building in. This process is part of the approval for a building permit. Lost Creek Designated Basin spans the three counties of Weld, Adams, and Arapahoe. Each county’s planning department approaches this approximately the same – prove there is water there that is suitable for your building plan. If a well exists on the property, this is an easy task. If no well exists on the property, the task is harder. Remember we said the state does not verify the determinations of water right? Correct. They do not. A right may exist on paper, but physically on a small land parcel, mudstone, claystone, or just very fine particle layers that preclude viable water may occlude a targeted aquifer. Lost Creek has been called a “fish bowl full of straws” in the past because of difficulty of finding water in some areas. Well drilling is a major investment so careful planning is essential to avoid costly mistakes.

Construction Guidelines

So, in regard to these issues, Lost Creek Groundwater Management District recommends you use reputable, licensed driller installers in the area and consider the following construction guidelines for your well and water system:

• Choose the most viable aquifer level from your determination of water right to apply for a well permit.
• Apply for the correct type of permit for the activities you intend to do on your parcel. (See permitted uses section)
• Select downhole and controller equipment that protects the pump and motor from damage if pressure is lost.
• Install the intake as low as possible in the well (your installer may try to save you short term expense but it will cost you later!)
• Consider a constant pressure system to preclude wear and tear on downhole equipment and plumbing.
• Consider water treatment for household uses (softening if hard, reverse osmosis for drinking, etc.)

Key Terms

• Formation - A geologic term describing a layer or consolidation of material with similar properties.
• Cascading water – an occurrence in high capacity wells where drawdown in the casing is below surrounding water and the water falls inside the casing
• Filter Pack - A coarse aggregate placed around the screened or perforated casing in a well to improve water flow
• Appropriation – an annual amount of water specified by the state for a permitted use
• Static Level – an elevation (normally expressed in feet above mean sea level) where the top of a layer of undisturbed water exists in an aquifer.
• Head Pressure - Pressure exerted by surrounding water which causes flow. In the case of a confined aquifer, head pressure forces water up the casing.
• Piezometric Level - A measured level of water in a system. This may be a static level or have some drawdown due to flow or demand.
• Drawdown - A dynamic level measured during pumping demand in a well. A thorough installation report will have a drawdown component noted.
• Sustained Rate - The amount of water in gallons per minute that a system can draw with a stable drawdown level.
• Specific Capacity - The amount of water that can be accessed by a pumping system per unit of head pressure in the aquifer system.
• Intake Level - The most important parameter of your well installation! Recommended 10’ above the well bottom to avoid sediment fouling.
• Submersible Pump - The most common pump type for domestic/residential well construction in Lost Creek.