Troubled Waters - How Human Activity, Changing Habits, and Drainage Have Reshaped the Spey and Deveron

For generations, the great rivers of the Scottish Highlands and Northeast, most notably the mighty River Spey and the winding River Deveron, have been celebrated as pristine wild rivers. They are the lifeblood of iconic Atlantic salmon and sea trout runs, the engine of world-renowned whisky distilleries, and the aesthetic spine of rural landscapes. Yet, beneath their clear surfaces lies a landscape, which for decades, has been undergoing quiet and subtle transformation. 

Since the 1950s, human activity across these catchments has fundamentally altered the volume, timing, and chemistry of the water flowing to the sea. Through huge postwar population shifts, changes in agricultural and forestry drainage, and changes via a modern domestic lifestyle, we have altered the hydrology of our river systems dramatically. 

Understanding what we have changed and how we can repair it requires examining the intersection of land management, human habits, and freshwater ecology.  

Population and Changing Habits 

In the decade following the Second World War, life along the Spey and Deveron was defined by a steady, but slow pace. The 1950s baseline across these catchments reflected a smaller permanent population and an entirely different relationship with domestic resources. 

The Demographic Shift 

The demographic evolution of Strathspey and the Deveron valley split along two distinct paths after 1950. 

On the Spey, the expansion of transport infrastructure, most notably the upgrading of the A9, and the development of Aviemore as a year-round tourism hub helped transform the valley. During the past 70 years, the permanent population in Badenoch and Strathspey has grown by roughly 40%, rising from around 8,000 to 14,000. With the populations of Towns such as Aberlour and Rothes growing at a similar rate. Furthermore, the establishment of the Cairngorms National Park in 2003 has accelerated tourism, bringing an estimated 1.7 to 2 million visitors annually. 

Lacking a high level tourist resort, the Deveron valley experienced more modest, steady population growth of roughly 15% during the same period, increasing from roughly 29,000 to over 33,000 residents, mainly centered around market towns like Huntly, Turriff, and Banff, with many new single dwellings along the riverbank. 

The Evolution of Domestic Habits 

While population figures tell part of the story, the way individual humans interact with water has changed even more dramatically. In 1950, the average UK resident consumed approximately 80 to 90 litres of water per day. Today, that figure stands at roughly 150 to 180 litres per day. 

Consider the humble act of washing clothes: 

Domestic Laundry Metric	1950s Household	Modern Household
Frequency	1 to 2 loads per week ("Wash Day")	5 to 8 loads per week
Appliance Type	Boiler, wringer/mangle, single tub	Automatic
Water per Load	150 – 190 Litres (40–50 gallons)	40 – 70 Litres (10–18 gallons)
Detergent Chemistry	Animal fats, simple lye [soap], sodium carbonate [Washing soda]	Synthetic surfactants, enzymes, optical brighteners[Whitening Agents], microplastics.

In the 1950s, laundry involved a day of physical work . Clothes were re-worn multiple times, and washing was concentrated into a single weekly routine. The arrival of automatic washing machines, showers, dishwashers, and modern sanitation eliminated this physical work. 

Paradoxically, while modern appliances are dramatically more efficient per cycle, using up to 70% less water per load than early mid-century washers—our habit of washing items after a single wear means total volume used remains high, whilst the chemical profile of that wastewater has become totally different. 

Water Entering the Catchment 

Water abstracted from the ground or river eventually returns to the river. However, modern municipal wastewater treatment plants, designed primarily in the mid-to-late 20th century, were built to address organic solids, nitrogen, and phosphorus. They were not engineered to strip out the complex synthetic materials of 21st-century living.

Lined with Alder Trees this is a typical pool on the River Spey

The Invisible Chemical Cocktail 

Every day, treated effluent discharges into river systems, carrying trace residues that survive standard municipal treatment: 

Pharmaceuticals & Hormones - Synthetic estrogens from oral contraceptives, hormone replacement therapies, anti-inflammatories, and antidepressants pass through human metabolism and treatment works into the water column. 

Veterinary Parasiticides: Modern spot-on flea treatments for pets, containing potent insecticides like fipronil and imidacloprid, enter domestic wastewater when pets are bathed, swim in local burns, or when hands are washed after application. These chemicals are toxic to aquatic invertebrates at concentrations measured in parts per trillion. 

Personal Care Products: Synthetic musks, surfactants, fire retardants, and microplastic fibers shed from synthetic garments during washing cycles flow continuously into downstream habitats. 

Impact on the Aquatic Food Web 

When these treated effluents enter low-flow summer rivers, they do not cause immediate fish kills; instead, they alter the biological community. 

Decline of Sensitive Insects  - High-grade aquatic insects, Ephemeroptera (Mayflies), Plecoptera (Stoneflies), and Trichoptera (Caddisflies), require clean, cold, highly oxygenated gravel beds. Organic micro-films and chemical residues coat these substrates, driving away sensitive nymphs. 

Rise of Tolerant Species - In place of large, caloric mayfly species, pollution-tolerant invertebrates flourish. Non-biting midges (Chironomids), blackfly larvae (Simuliidae), and freshwater shrimp (Gammarus) take over. Total invertebrate biomass may remain stable, but the diversity and nutritional quality of the hatch plummets. Jimmy Grey, the River Spey Superintendent, talked about this a great deal in the 1990s but, because, unlike today, it didn’t fit any political agenda or narrative,  was largely ignored.   

Sub-Lethal Stress on Salmonids - Young salmon parr and sea trout fry feed on these altered insect populations. Forced to expend more energy chasing tiny midge larvae rather than feeding on large mayfly nymphs, juvenile growth rates slow. Simultaneously, exposure to endocrine-disrupting chemicals impairs their olfactory senses; the very navigational tool adult salmon rely on to smell their way home from the Atlantic Ocean years later. 

Forest and Agricultural Drainage 

While chemical inputs changed at the tap, the physical structure of the surrounding land was undergoing an even more radical transformation. The mid-to-late 20th century saw state-subsidized efforts to maximize agricultural yield and timber independence across Scotland. 

HISTORICAL DRAINAGE (1950s–1980s)    MODERN HYDROLOGICAL RESULT

Hill Grip Cutting                       Rapid Water Shedding [Faster run off]         │ Peatland Ditching              Flashy Flood Peaks [Elgin and towns like it required expensive flood prevention]            

Straightened Field Ditches             Reduced Summer Baseflow [Quick Run off]      │ Dense Commercial Forestry              • Severe Streambed Scouring & Acidification  

"Hill Gripping" and Peatland Desiccation 

From the 1950s through the 1980s, government grants encouraged landowners to drain upland bogs, moors, and headwaters to support forestry management. Hundreds of miles of deep open trenches known as hill grips were cut directly into the peatlands of the upper Spey and Deveron catchments. 

Loss of the Upland Sponge - Intact peatlands function as natural sponges, absorbing massive quantities of rainfall and releasing it slowly over weeks and months. 

Accelerated Runoff - Gripping converted these sponges into highway systems for rain. Water that once took days to seep through Sphagnum moss now rushes into valley streams in hours. 

Commercial Forestry 

Concurrently, post-war forestry policy led to widespread planting of dense, non-native conifer plantations (such as Sitka spruce). To prepare wet upland soils for planting, deep drainage furrows were ploughed into the hillside. 

When these dense forests mature, their canopy intercepts rain, evaporating up to 30% of it before it reaches the ground. However, when heavy storm events occur or when clear-felling takes place, the ploughed furrows channel water and loose sediment directly into headwater burns, smothering spawning gravels in fine silt.  

The cumulative effect of this landscape drainage is a fundamental change in river hydrology.

Reduced Dry-Weather Baseflow 

Rivers become flashier. During rain events, water levels spike rapidly, scouring the riverbed and washing away delicate insect larvae and salmon eggs. Conversely, during dry summer periods, because the upland sponge has been drained dry, water levels drop lower and faster than they ever did in the 1950s. Although many would like to point the finger toward it, none of this was caused by Climate Change. However - 

Temperature and Dilution 

The combination of modified drainage and naturally changing climate patterns leading to less winter snow accumulations manifests most acutely during the summer months. When summer flows drop, two environmental pressures collide - Thermal stress and pollutant concentration. 

The Physics of Warming Water 

Water possesses a high heat capacity, but as volume drops, its ability to buffer against atmospheric heat collapses. 

Reduced Thermal Mass - In shallow, slow-moving low-flow water, solar radiation heats the riverbed rapidly. 

Loss of Shade - Agricultural land clearance along the Deveron and lower Spey removed native riparian trees (willows, alders, and oaks), exposing long stretches of water directly to the sun. 

When water temperatures cross 18°C (64.4°F), Atlantic salmon experience physiological stress, reducing their metabolic efficiency. At 23°C (73.4°F), prolonged exposure becomes lethal. Furthermore, warmer water physically holds less dissolved oxygen at the precise time that Coldwater fish need it most. 

              CRITICAL THERMAL THRESHOLDS (SALMONIDS) 

< 16°C (60.8°F) - Optimal growth and active in river feeding [Trout and Juvenile Salmon]                

18°C (64.4°F) - Physiological stress begins; feeding drops [Happy time for Predators]    

20°C (68.0°F) - Severe stress; adult migration halts [Happy time for Saltwater Predators as returning adult salmon linger in salt and brackish water.          

> 23°C (73.4°F) - LETHAL ZONE for prolonged exposure [Fish that don’t die struggle to reproduce]  

The Dilution Deficit 

During high winter flows, the effluent discharged from municipal treatment plants and industrial sites is diluted by thousands of parts of fresh water. 

However, In a low-flow summer, that dilution factor vanishes. In smaller tributaries, treated effluent and agricultural run-off make up a much higher proportion of the total volume. The river is stripped of its ability to self-purify, turning minor chemical inputs into major problems for aquatic life. 

Remediation Strategies 

We cannot roll back the clock to 1950, nor can we strip modern homes of sanitation and washing facilities. However, we can redesign our relationship with river catchments through targeted, nature-based solutions and updated infrastructure. 

To safeguard the Spey, the Deveron, and similar coldwater ecosystems against further human-driven change; restoration must address both land management and human water habits. 

                         CATCHMENT RESTORATION                                     │           

A. Upland Peatland Restoration and "Grip Blocking" 

The most effective way to restore natural summer baseflows is to fix the sponge at the top of the catchment. In the case of the Spey this is taking water back from those who have stolen it. "Release the Spey" [See below].  

Re-wetting Bogs: Programs like Peatland ACTION in Scotland are systematically blocking thousands of miles of historical hill grips using peat dams. On a biiger scale, This could also be used as part of storing water to be used in times of low flow.  

Hydrological Recovery - Blocking grips slows water down, encouraging Sphagnum moss to re-establish. This holds water in the uplands during winter storms, mitigating downstream flooding while ensuring a steady, cool release of groundwater to sustain river flows during summer droughts. 

Riparian Woodland Restoration ("Managing for Microclimates") 

To combat rising summer water temperatures, riverbanks must be re-vegetated with native broadleaf trees such as willow. This need not impact negatively on fisheries [See my example at Lower Pitchroy when I did this long before it became fashionable in the mid 1990s] See Here - https://youtube.com/shorts/-5xC5YAYj5k?si=oLx0U0kjXKDyc-uv 

Thermal Blanketing: Planting willows, with intention to shape and coppice. Done correctly [Not simply planting willy nilly] has the potential to drop local water temperatures by 2°C to 4°C on hot summer days. [Medium to long term]  

Simply planting trees is not enough, managing those properly is essential. And in the case of the Spey, mitigates[in a small way, for the loss of water in the upper catchment.   

Upgrading Wastewater Infrastructure and Chemical Stewardship 

Addressing chemical inputs requires action at both municipal and individual levels: 

Tertiary Wastewater Treatment - Water utility providers must continue upgrading wastewater treatment works along sensitive river corridors with advanced filtration technologies (such as membrane bioreactors and granular activated carbon) capable of capturing micro-pharmaceuticals, endocrine disruptors, and synthetic chemicals. 

Veterinary and Household Awareness - Public awareness campaigns regarding pet flea treatments can dramatically cut chemical inputs. Dog owners should be advised against letting pets swim in rivers or washing them immediately after spot-on pesticide applications. 

Consumer Habits - Shifting domestic habits back toward thoughtful resource use—running full laundry loads, choosing eco-friendly detergent formulations, and reducing daily per-capita water demand through greywater recycling—eases pressure on public abstractions and treatment infrastructure alike. 

Hydrogen Development - 

Having already been stopped at planning stage, A proposed site at Marypark (near Ballindalloch). Following the acquisition of the portfolio by Protium, new developers have signaled intent to review or reshape the concept, though it remains a subject of ongoing local discussion and concerns. Listed below are the main concerns. 

• To produce 1 kg of hydrogen, the process chemically consumes 9 kg (litres) of ultra-pure water as a raw material. 

• Real-World Consumption - When accounting for cooling water, purification losses, and pre-treatment backwashing, industrial electrolysers typically consume between 15 and 25 litres of raw water per kilogram of hydrogen produced. 

• Scale of Abstraction - At the planned 70MW capacity for Speyside Hydrogen, the facility would require millions of litres of raw water annually. If this water is drawn directly from local groundwater or Spey tributaries during dry summer months, it adds yet another abstraction load to a mainstem already dealing with climate-driven low flows, forestry drainage, and existing distillery draws. 

• Alternative Water Sourcing (No Low-Flow Abstraction) - The facility should be prohibited from abstracting directly from local burns or shallow groundwater during summer low-flow conditions. Solutions include building off-river storage lagoons filled during high winter flows or using closed-loop recycling systems to minimise consumption. 

• Strict Thermal and Effluent Limits - Any cooling water or wastewater discharged back into the catchment must be strictly monitored for temperature spikes and chemical residues to prevent further thermal stress on juvenile salmonids. 

• Site Selection Scrutiny: "Planning rationale" must be tested against alternative, less environmentally sensitive brownfield sites nearby that offer grid access without requiring construction within the river's dynamic hydrological zone. 

The "Release The Spey" Campaign 

A complete picture of the human impact on the River Spey cannot be drawn without examining what occurs at the very head of the catchment. 

While domestic, agricultural, and distillery uses borrow and return water within the valley, hydroelectric schemes permanently remove vast volumes of water out of the Spey catchment entirely, transferring it to the West Coast and the Tay catchment. 

The Two Major Schemes 

Spey Dam (66% of Abstractions): Constructed in 1943 under wartime Emergency Powers to supply power for the UK’s only aluminium smelter at Fort William. Operated today by GFG Alliance / Alvance, Spey Dam impounds the headwaters near Laggan and is licensed to divert up to 85% of the natural flow from the top 12 miles of the Spey through mountain tunnels into Loch Laggan and Loch Treig. 

SSE Tummel Valley Scheme (25% of Abstractions): Operated by Scottish and Southern Energy, this scheme intercepts key upper tributaries—including the River Truim, River Tromie, River Cuaich, and Allt Bhran. Instead of allowing these streams to feed the Spey, the water is piped south into Loch Ericht and ultimately discharged into the River Tay catchment. 

The Ecological Damage 

Stripping 91% of the water from the headwaters for over 80 years has caused compound ecological damage throughout the entire river network.  

Depletion of Groundwater Storage - Headwaters naturally charge the deep gravel and shingle substrates along the riverbed. Decades of continuous abstraction have denuded this subterranean "groundwater bank." Without groundwater naturally seeping back into the river, the Spey has lost its buffer during dry summer months. 

Blockade to Migration - In 2015, the Scottish Environment Protection Agency (SEPA) formally classified Spey Dam as a major barrier to fish passage. Surveys revealed an almost complete absence of young-of-the-year salmon parr and fry above the dam, effectively cutting off miles of prime high-altitude spawning habitat. 

Loss of Cold, Oxygen-Rich Water - The upper tributaries provide the coldest, most oxygen-dense water in the entire system. Removing this flow drastically lowers downstream dissolved oxygen levels. During summer heatwaves, these missing headwater flows exacerbate "oxygen sags," which have resulted in localized mass fish kills of adult salmon and sea trout. 

In response to worsening summer low-flows and declining wild salmon stocks, in 2021, the Spey Fishery Board (SFB), alongside the Missing Salmon Alliance and local communities, launched the Release the Spey campaign. 

Key Demands & Short-Term Actions 

Immediate Compensation Flows The campaign calls on SEPA and the hydro operators to release water back into key tributaries, such as the River Mashie, River Cuaich, and Allt Bhran, rather than piping it out of the catchment. Re-watering these streams immediately reopens critical spawning habitat. 

Modernizing Outdated Legislation - Much of the water abstraction at Spey Dam is protected under Second World War Acts of Parliament written long before modern environmental standards existed. Campaigners are lobbying the Scottish Government to reappraise these historical licences. 

Building Climate Resilience - As summer droughts become more frequent, returning headwater flows to the Spey is seen as the single most effective action available to lower water temperatures, maintain oxygen levels, and restore the natural hydrology needed to safeguard Atlantic salmon for the future. 

Release The Spey successfully won the argument; no one, including SEPA, can now deny that the headwater diversions are ecologically damaging the river. And are the best and most effective ways of ensuring the river is supplied with sufficient cool water. However, converting that political victory into actual gallons of water passing down the riverbed is bogged down in bureaucratic reviews, regulatory deadlines set for 2027, and commercial resistance from power generators and 5 years since initiating “Release the Spey”, not a drop of water has been diverted to the River.  

A Flow for the Future 

The dramatic changes experienced across the Spey and Deveron over the past 70 years reveal just how deeply human life is tied to freshwater ecosystems. From my own lifetime on the water, through the decline in Salmon, they also highlight the vital cultural, historical, and economic importance of "The Business of Salmon Fishing" to our valleys. 

Modern standards of living, intensive land drainage, and altered water chemistry have fundamentally reshaped the hydrology of these catchments. In doing so, we have compromised the ability of our rivers to produce healthy juvenile salmon, mirroring the historical decline of continental rivers like e.g. the Rhine, Loire, and Seine. I see exactly the opposite when I visited the Ponoi river in Russia and a great many in Iceland. Rivers which are difficult to access, remote and well away from the hand of man, interestingly, but unsurprisingly, are the ones fairing best. 

When juvenile production fails, the biological artery of a river is cut. Ours has been severely restricted for decades. Because systematic juvenile surveying didn't begin until the late 1990s, by which time parr and fry numbers were already in freefall, we were lulled into a dangerous, false sense of security about what a truly healthy river baseline looks like.  

Yet, just as deliberate human actions drove these shifts, deliberate human stewardship has the potential to repair them. However, as is plainly obvious by government action with regard to the Release the Spey Campaign than many things come before the longevity of this business. The chain of regulatory bodies at different layers has done all in their power to stall any progress. However, it must also be pointed out, a great many people are employed in this act of stalling. This is an industry within itself.  

In this Blog, I highlight only the key areas affected by man and have purposely omitted the impact of increased natural predation on salmon by increased numbers of piscivorous birds, as well as mammals such as Seals and Dolphins.